UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM N-CSR CERTIFIED SHAREHOLDER REPORT OF REGISTERED MANAGEMENT INVESTMENT COMPANIES 		Investment Company Act file number 811-21108 Pioneer Series Trust X (Exact name of registrant as specified in charter) 60 State Street, Boston, MA 02109 (Address of principal executive offices) (ZIP code) Terrence J. Cullen, Pioneer Investment Management, Inc., 60 State Street, Boston, MA 02109 (Name and address of agent for service) Registrant's telephone number, including area code: (617) 742-7825 Date of fiscal year end: March 31 Date of reporting period: April 1, 2017 through September 30, 2017 Form N-CSR is to be used by management investment companies to file reports with the Commission not later than 10 days after the transmission to stockholders of any report that is required to be transmitted to stockholders under Rule 30e-1 under the Investment Company Act of 1940 (17 CFR 270.30e-1). The Commission may use the information provided on Form N-CSR in its regulatory, disclosure review, inspection, and policymaking roles. A registrant is required to disclose the information specified by Form N-CSR, and the Commission will make this information public. A registrant is not required to respond to the collection of information contained in Form N-CSR unless the Form displays a currently valid Office of Management and Budget ("OMB") control number. Please direct comments concerning the accuracy of the information collection burden estimate and any suggestions for reducing the burden to Secretary, Securities and Exchange Commission, 450 Fifth Street, NW, Washington, DC 20549-0609. The OMB has reviewed this collection of information under the clearance requirements of 44 U.S.C. ss. 3507. ITEM 1. REPORTS TO STOCKHOLDERS. Pioneer Dynamic Credit Fund -------------------------------------------------------------------------------- Semiannual Report | September 30, 2017 -------------------------------------------------------------------------------- Ticker Symbols: Class A RCRAX Class C RCRCX Class Y RCRYX [LOGO] Amundi Pioneer ============== ASSET MANAGEMENT visit us: www.amundipioneer.com Table of Contents President's Letter 2 Portfolio Management Discussion 4 Portfolio Summary 10 Prices and Distributions 11 Performance Update 12 Comparing Ongoing Fund Expenses 15 Schedule of Investments 17 Financial Statements 43 Notes to Financial Statements 50 Additional Information 68 Trustees, Officers and Service Providers 70 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 1 President's Letter Robust, synchronized global economic growth and rising corporate profits have continued to drive strong performance in both the credit and equity markets for most of 2017. U.S. stocks, as measured by the Standard & Poor's 500 Index, have returned 14.23% year-to-date through September 30, 2017. Fixed-income markets, while not generating the same dazzling returns as equities, have held their own, led by high-yield securities, which produced a year-to-date return of 7.05% in the U.S., as measured by the Bank of America Merrill Lynch U.S. High Yield Index. Meanwhile, the Bloomberg Barclays U.S. Aggregate Bond Index has returned 3.14% since the start of the calendar year. Continued strong employment numbers and higher consumer confidence, together with solid global economic growth and a depreciating U.S. dollar contributed to better-than-expected U.S. gross domestic product (GDP) growth of 3.1% in the second quarter. Outside the U.S., economic growth in the second quarter also surprised to the upside across the Euro zone, China, and Japan. Meanwhile, despite higher oil and commodities prices, inflation continued to be moderate, both in the U.S. and globally, enabling major non-U.S. central banks to maintain their easy monetary policies. As expected, however, the U.S. Federal Reserve System (the Fed) recently announced that it would commence tapering its balance sheet this October. The Fed also appears primed to raise interest rates one more time before the end of this year, which would be the fourth rate increase since December of 2016. As we move into the final months of 2017, we believe the U.S. economy will experience modest growth in the short term, depending on the mix of economic policies enacted as the country moves away from monetary stimulus (driven by the Fed) and toward fiscal stimulus (potentially including tax reform) as well as lighter regulatory burdens. Meanwhile, corporate earnings remain solid and we think they will improve even further, despite some pressure from wage increases. In addition, as the economy continues to grow and we begin to see a modest upturn in inflation, we believe the Fed will continue to raise interest rates. While economic and market conditions appear solid, there are always risks to consider that could dampen the outlook. Geopolitical concerns, such as increased tensions with North Korea, and continued political gridlock in Washington are just some of the risks that could lead to increased market volatility. 2 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 It is for those reasons that we at Amundi Pioneer continue to believe that investors can benefit from the experience and tenure of our investment teams who make active and informed decisions across our funds. As always, and particularly during times of market uncertainty, we encourage you to work with your financial advisor to develop an overall investment plan that addresses both your short- and long-term goals, and to implement such a plan in a disciplined manner. We greatly appreciate the trust you have placed in us and look forward to continuing to serve you in the future. Sincerely, /s/ Lisa M. Jones Lisa M. Jones Head of the Americas, President and CEO of U.S. Amundi Pioneer Asset Management USA, Inc. September 30, 2017 Any information in this shareowner report regarding market or economic trends or the factors influencing the Fund's historical or future performance are statements of opinion as of the date of this report. Past performance is no guarantee of future results. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 3 Portfolio Management Discussion | 9/30/17 Steady economic growth and improving corporate profits supported the more credit-sensitive sectors in the fixed-income market during the six-month period ended September 30, 2017. In the following interview, Michael Temple and Kevin Choy discuss the principal factors that affected the performance of the Pioneer Dynamic Credit Fund during the six-month period. Mr. Temple, Director of Corporate Credit Research, U.S., a senior vice president, and a portfolio manager at Amundi Pioneer Asset Management, Inc. ("Amundi Pioneer"), and Mr. Choy, a vice president and a portfolio manager at Amundi Pioneer, are responsible for the day-to-day management of the Fund. Q How did the Fund perform during the six-month period ended September 30, 2017? A Pioneer Dynamic Credit Fund's Class A shares returned 2.51% at net asset value during the six-month period ended September 30, 2017, while the Fund's benchmark, the Bank of America Merrill Lynch U.S. Dollar 3-Month LIBOR Index (the BofA ML Index), returned 0.59%. During the same period, the average return of the 285 mutual funds in Lipper's Alternative Credit Focus Funds category was 2.22%, and the average return of the 359 mutual funds in Morningstar's Non-Traditional Bond Funds category was 2.05%. Q How would you describe the investment environment in the fixed-income markets during the six-month period ended September 30, 2017? A The backdrop in the global fixed-income markets during the six months was benign. The domestic economy expanded persistently, with the most recent reports on growth in U.S. gross domestic product (GDP), for example, showing that the economy grew at a 3.1% annual pace in the second quarter of 2017. Meanwhile, corporate earnings for the first quarter were 14.9% higher than a year earlier. Over the period, the U.S. Federal Reserve (the Fed) raised the Federal Funds rate just once, in June 2017, after enacting two rate hikes in the prior six months, with one more increase expected before the end of the year. This was an indication that the Fed seemed committed to acting with restraint in tightening monetary policy and moving toward a less-accommodative stance. However, the Fed did announce late in the period that it was prepared to begin reducing its balance sheet by shedding some of the holdings it purchased during its multiple quantitative-easing programs between 2008 and 2014. 4 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 Elsewhere around the globe, Asia's economy and the emerging markets generally benefited from a major stimulus package by China's central government in 2016. Japan's economy also improved and confidence started rising, while the European economy proved stronger than earlier expectations. All of those factors helped drive the global rally in riskier assets during the period, including equities and credit-sensitive fixed-income securities. A weakening U.S. dollar (USD) also aided currencies and markets overseas. In the U.S. fixed-income markets, lower-quality securities generally outperformed higher-rated debt as the spreads between those credit tiers narrowed. (Credit spreads are commonly defined as the differences in yield between Treasuries and other types of fixed-income securities with similar maturities.) Among corporate bonds, both high-yield and investment-grade debt performed positively during the period, with high yield returning more than 4% and investment grade returning roughly 2%. Q What were the principal factors that affected the Fund's performance during the six-month period ended September 30, 2017? A The Fund performed well during the period, principally because of our focus on the more credit-sensitive sectors of the market, including both investment-grade and high-yield corporate debt. The Fund's duration exposure also had a positive effect on performance. (Duration is a measure of the sensitivity of the price, or the value of principal, of a fixed-income investment to a change in interest rates, expressed as a number of years. Short-duration portfolios tend to fare well when interest rates rise and price risk increases, while longer-duration portfolios tend to do better when interest rates decline and opportunities for price appreciation increase.) Solid performance from the portfolio's credit-sensitive holdings tended to reach across all sectors, with no major themes influencing the Fund's results. Individual corporate holdings in the portfolio that performed well during the period included the bonds of Sprint, a wireless service provider, and of International Game Technology, a company that designs and produces gaming equipment and systems. While overall performance was positive during the period, the Fund did have some investments that disappointed, including the debt of CenturyLink, a telecommunications operator, and of Pet Smart, which operates a chain of retail stores selling pet products. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 5 Q Did you make any changes to the Fund's positioning during the six-month period ended September 30, 2017? A Over the six months, we slightly decreased the portfolio's overall level of credit risk as credit spreads tightened. In terms of allocation shifts during this timeframe, we reduced the Fund's investments in high-yield corporate bonds and longer-duration investment-grade corporates, while increasing exposure to bank loans. At this point of the business and credit cycles, we are finding select opportunities in the bank-loan market, which have floating interest rates and are typically of the senior secured variety. At the end of the six-month period, the Fund's largest allocations by sector were to U.S. corporate bonds, at 36% of the Fund's total investment portfolio, followed by senior secured loans (19%), U.S. government securities (16%), and international corporate bonds (just under 15%). As of September 30, 2017, the Fund's average effective duration was 3.93 years. Q How did the Fund's exposure to derivative securities affect performance over the six-month period ended September 30, 2017? A The Fund had investments in several types of derivative securities during the period. We purchased credit default swaps to manage the portfolio's exposure to credit-linked securities, and the swaps tended to help performance. We also invested in interest-rate futures to help manage the Fund's duration risk, and some forward foreign currency contracts (currency forwards) to manage the risks associated with the portfolio's exposures to investments denominated in foreign currencies. Neither the interest-rate futures nor the currency forwards had material effects on the Fund's relative performance. However, the cost to the Fund of our investments in options contracts did act as a drag on results. We invested in the options to guard against the risk of a sharp sell-off in the credit markets. However, the credit markets suffered no significant reversals during the six-month period, and so the cost of the options contracts detracted from the Fund's results. Q Was there any change in the Fund's yield, or distributions to shareholders, during the six-month period ended September 30, 2017? A Yes, the Fund's yield declined during the period as overall yields in the credit market fell. 6 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 Q What is your investment outlook? A While economic fundamentals appear solid and corporate profit trends are healthy, we find current valuations less compelling given that prices in the credit markets have risen in the wake of a brisk rally that has lasted for nearly 18 months. As we noted earlier, spreads between lower-quality and higher-quality debt have compressed significantly. Over the next 12 months, we expect to maintain a relatively stable roster of holdings in the Fund's portfolio, although we think insurance-linked securities, including so-called catastrophe bonds, may offer interesting opportunities late in 2017. The asset class turned in negative performance in September after three major hurricanes made landfall in the U.S. and Caribbean, and two earthquakes struck Mexico over the final weeks of the period. However, we believe the impending renewal season for insurance- linked securities could create some attractive pricing opportunities within that market for the upcoming year, and we continue to be constructive on the diversifying* nature of the asset class, as the securities are not highly correlated with the performance of other fixed-income assets. (Correlation represents the degree to which assets or asset class prices have moved in relation to one another. Correlation ranges from -1, where assets/asset prices always move in opposite directions, through 0, where assets/asset prices are absolutely independent, to 1, where assets/asset prices always move together.) Please refer to the Schedule of Investments on pages 17-42 for a full listing of Fund securities. All investments are subject to risk, including the possible loss of principal. In the past several years, financial markets have experienced increased volatility, depressed valuations, decreased liquidity and heightened uncertainty. These conditions may continue, recur, worsen or spread. Pioneer Dynamic Credit Fund has the ability to invest in a wide variety of debt securities. The Fund may invest in underlying funds, including ETFs. In addition to the Fund's operating expenses, you will indirectly bear the operating expenses of investments in any underlying funds. * Diversification does not assure a profit nor protect against loss. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 7 The Fund and some of the underlying funds utilize strategies that have a leveraging effect on the Fund, which increases the volatility of investment returns and subjects the Fund to magnified losses if the Fund's or an underlying fund's investments decline in value. The Fund and some of the underlying funds may use derivatives, such as options and futures, which can be illiquid, may disproportionately increase losses, and have a potentially large impact on Fund performance. The Fund may invest in inflation-linked securities. As inflationary expectations increase, inflation-linked securities may become more attractive, because they protect future interest payments against inflation. Conversely, as inflationary concerns decrease, inflation-linked securities will become less attractive and less valuable. The Fund may invest in credit default swaps, which may in some cases be illiquid, and they increase credit risk since the Fund has exposure to both the issuer of the referenced obligation and the counterparty to the credit default swap. The Fund may invest in floating-rate loans. The value of collateral, if any, securing a floating-rate loan can decline or may be insufficient to meet the issuer's obligations or may be difficult to liquidate. The Fund may invest in event-linked bonds. The return of principal and the payment of interest on event-linked bonds are contingent on the nonoccurrence of a pre-defined "trigger" event, such as a hurricane or an earthquake of a specific magnitude. The Fund may invest in zero coupon bonds and payment-in-kind securities, which may be more speculative and fluctuate more in value than other fixed income securities. The accrual of income from these securities are payable as taxable annual dividends to shareholders. Investments in equity securities are subject to price fluctuation. Investments in fixed-income securities involve interest rate, credit, inflation, and reinvestment risks. As interest rates rise, the value of fixed-income securities generally falls. The Fund may invest in mortgage-backed securities, which during times of fluctuating interest rates may increase or decrease more than other fixed- income securities. Mortgage-backed securities are also subject to pre-payments. 8 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 Prepayment risk is the chance that an issuer may exercise its right to prepay its security, if falling interest rates prompt the issuer to do so. Forced to reinvest the unanticipated proceeds at lower interest rates, the Fund would experience a decline in income and lose the opportunity for additional price appreciation. High-yield bonds possess greater price volatility, illiquidity, and possibility of default. There is no assurance that these and other strategies used by the Fund or underlying funds will be successful. The Fund is not intended to outperform stocks and bonds during strong market rallies. These risks may increase share price volatility. Please see the prospectus for a more complete discussion of the Fund's risks. Before investing, consider the product's investment objectives, risks, charges and expenses. Contact your advisor or Amundi Pioneer Asset Management, Inc., for a prospectus or summary prospectus containing this information. Read it carefully. Any information in this shareholder report regarding market or economic trends or the factors influencing the Fund's historical or future performance are statements of opinion as of the date of this report. Past performance is no guarantee of future results. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 9 Portfolio Summary | 9/30/17 Portfolio Diversification* -------------------------------------------------------------------------------- (As a percentage of total investment portfolio) [THE FOLLOWING DATA WAS REPRESENTED AS A PIE CHART IN THE PRINTED MATERIAL] U.S. Corporate Bonds 36.1% Senior Secured Loans 19.2% U.S. Government Securities 16.1% International Corporate Bonds 14.6% Collateralized Mortgage Obligations 5.2% Asset Backed Securities 2.6% Closed End Fund 2.6% Foreign Government Bonds 1.6% Convertible Preferred Stocks 1.0% Convertible Corporate Bonds 0.5% Temporary Cash Investment 0.5% U.S. Common Stock 0.0%** * Includes investments in insurance linked securities totaling 3.0% of total investment portfolio. ** Amount rounds to less than 0.1%. 10 Largest Holdings -------------------------------------------------------------------------------- (As a percentage of total long-term holdings)*** 1. U.S. Treasury Notes, 1.875%, 5/31/22 3.78% -------------------------------------------------------------------------------- 2. U.S. Treasury Bonds, 4.5%, 2/15/36 3.14 -------------------------------------------------------------------------------- 3. U.S. Treasury Bills, 10/12/17 2.86 -------------------------------------------------------------------------------- 4. Pioneer ILS Interval Fund 2.70 -------------------------------------------------------------------------------- 5. U.S. Treasury Notes, 1.125%, 6/30/21 2.05 -------------------------------------------------------------------------------- 6. U.S. Treasury Bills, 10/19/17 1.93 -------------------------------------------------------------------------------- 7. HCA, Inc., 5.25%, 4/15/25 1.15 -------------------------------------------------------------------------------- 8. CenturyLink, Inc., 5.8%, 3/15/22 1.12 -------------------------------------------------------------------------------- 9. Centene Corp., 4.75%, 1/15/25 1.03 -------------------------------------------------------------------------------- 10. Videotron, Ltd., 5.375%, 6/15/24 (144A) 0.96 -------------------------------------------------------------------------------- *** This list excludes temporary cash investments and derivative instruments. The Fund is actively managed, and current holdings may be different. The holdings listed should not be considered recommendations to buy or sell any security listed. 10 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 Prices and Distributions | 9/30/17 Net Asset Value per Share -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Class 9/30/17 3/31/17 -------------------------------------------------------------------------------- A $9.42 $9.39 -------------------------------------------------------------------------------- C $9.39 $9.36 -------------------------------------------------------------------------------- Y $9.46 $9.42 -------------------------------------------------------------------------------- Distributions per Share: 4/1/17-9/30/17 -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Short-Term Long-Term Class Dividends Capital Gains Capital Gains -------------------------------------------------------------------------------- A $0.2050 $-- $-- -------------------------------------------------------------------------------- C $0.1703 $-- $-- -------------------------------------------------------------------------------- Y $0.2196 $-- $-- -------------------------------------------------------------------------------- The Bank of America Merrill Lynch U.S. Dollar 3-Month LIBOR Index is an unmanaged index that tracks the performance of a synthetic asset paying the London Interbank Offered Rate (LIBOR), with a constant 3-month average maturity. The index is based on the assumed purchase at par value of a synthetic instrument having exactly its stated maturity and with a coupon equal to that day's 3-month LIBOR rate. Index returns assume reinvestment of dividends and, unlike Fund returns, do not reflect any fees, expenses or sales charges. It is not possible to invest directly in an index. The index defined here pertains to the "Value of $10,000 Investment" and "Value of $5 Million Investment" charts on pages 12-14. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 11 Performance Update | 9/30/17 Class A Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $10,000 investment made in Class A shares of Pioneer Dynamic Credit Fund at public offering price during the periods shown, compared to that of the Bank of America (BofA) Merrill Lynch (ML) U.S. Dollar 3-Month LIBOR Index. Average Annual Total Returns (As of September 30, 2017) -------------------------------------------------------------------------------- BofA ML Net Public U.S. Dollar Asset Offering 3-Month Value Price LIBOR Period (NAV) (POP) Index -------------------------------------------------------------------------------- Life-of-Class (4/29/11) 3.76% 3.02% 0.45% 5 year 3.72 2.76 0.47 1 year 5.91 1.18 1.02 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated August 1, 2017) -------------------------------------------------------------------------------- Gross -------------------------------------------------------------------------------- 1.22% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Pioneer Dynamic BofA ML U.S. Dollar Credit Fund 3-Month LIBOR Index 4/11 $9,550 $10,000 9/11 $9,122 $10,009 9/12 $10,086 $10,058 9/13 $10,483 $10,090 9/14 $10,957 $10,114 9/15 $10,665 $10,140 8/16 $11,392 $10,190 9/17 $12,107 $10,294 Call 1-800-225-6292 or visit www.amundipioneer.com for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted. The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost. NAV results represent the percent change in net asset value per share. Returns would have been lower had sales charges been reflected. POP returns reflect deduction of maximum 4.50% sales charge. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ. Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. Please refer to the financial highlights for a more current expense ratio. 12 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 Performance Update | 9/30/17 Class C Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $10,000 investment made in Class C shares of Pioneer Dynamic Credit Fund during the periods shown, compared to that of the Bank of America (BofA) Merrill Lynch (ML) U.S. Dollar 3-Month LIBOR Index. Average Annual Total Returns (As of September 30, 2017) -------------------------------------------------------------------------------- BofA ML U.S. Dollar 3-Month If If LIBOR Period Held Redeemed Index -------------------------------------------------------------------------------- Life-of-Class (4/29/11) 2.95% 2.95% 0.45% 5 year 2.93 2.93 0.47 1 year 5.12 5.12 1.02 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated August 1, 2017) -------------------------------------------------------------------------------- Gross -------------------------------------------------------------------------------- 1.98% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Pioneer Dynamic BofA ML U.S. Dollar Credit Fund 3-Month LIBOR Index 4/11 $10,000 $10,000 9/11 $ 9,517 $10,009 9/12 $10,434 $10,058 9/13 $10,753 $10,090 9/14 $11,156 $10,114 9/15 $10,778 $10,140 9/16 $11,466 $10,190 9/17 $12,054 $10,294 Call 1-800-225-6292 or visit www.amundipioneer.com for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted. The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost. Class C shares held for less than one year are subject to a 1% contingent deferred sales charge (CDSC). "If Held" results represent the percent change in net asset value per share. Returns would have been lower had sales charges been reflected. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ. Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. Please refer to the financial highlights for a more current expense ratio. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 13 Performance Update | 9/30/17 Class Y Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $5 million investment made in Class Y shares of Pioneer Dynamic Credit Fund during the periods shown, compared to that of the Bank of America (BofA) Merrill Lynch (ML) U.S. Dollar 3-Month LIBOR Index. Average Annual Total Returns (As of September 30, 2017) -------------------------------------------------------------------------------- BofA ML Net U.S. Dollar Asset 3-Month Value LIBOR Period (NAV) Index -------------------------------------------------------------------------------- Life-of-Class (4/29/11) 4.14% 0.45% 5 year 4.06 0.47 1 year 6.23 1.02 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated August 1, 2017) -------------------------------------------------------------------------------- Gross Net -------------------------------------------------------------------------------- 0.99% 0.88% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $5 Million Investment Pioneer Dynamic BofA ML U.S. Dollar Credit Fund 3-Month LIBOR Index 4/11 $5,000,000 $5,000,000 9/11 $4,800,067 $5,004,742 9/12 $5,318,483 $5,028,849 9/13 $5,549,790 $5,044,939 9/14 $5,816,604 $5,057,112 9/15 $5,674,308 $5,069,978 9/16 $6,108,169 $5,095,071 9/17 $6,488,624 $5,147,121 Call 1-800-225-6292 or visit www.amundipioneer.com for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted. The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost. Class Y shares are not subject to sales charges and are available for limited groups of eligible investors, including institutional investors. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ. Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information. The net expense ratio reflects the contractual expense limitation currently in effect through August 1, 2018, for Class Y shares. There can be no assurance that Amundi Pioneer will extend the expense limitation beyond such time. Please see the prospectus for more information. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. Please refer to the financial highlights for a more current expense ratio. 14 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 Comparing Ongoing Fund Expenses As a shareowner in the Fund, you incur two types of costs: (1) ongoing costs, including management fees, distribution and/or service (12b-1) fees, and other Fund expenses; and (2) transaction costs, including sales charges (loads) on purchase payments. This example is intended to help you understand your ongoing expenses (in dollars) of investing in the Fund and to compare these costs with the ongoing costs of investing in other mutual funds. The example is based on an investment of $1,000 at the beginning of the Fund's latest six-month period and held throughout the six months. Using the Tables -------------------------------------------------------------------------------- Actual Expenses The first table below provides information about actual account values and actual expenses. You may use the information in this table, together with the amount you invested, to estimate the expenses that you paid over the period as follows: (1) Divide your account value by $1,000 Example: an $8,600 account value (divided by) $1,000 = 8.6 (2) Multiply the result in (1) above by the corresponding share class's number in the third row under the heading entitled "Expenses Paid During Period" to estimate the expenses you paid on your account during this period. Expenses Paid on a $1,000 Investment in Pioneer Dynamic Credit Fund Based on actual returns from April 1, 2017, through September 30, 2017. -------------------------------------------------------------------------------- Share Class A C Y -------------------------------------------------------------------------------- Beginning Account $1,000.00 $1,000.00 $1,000.00 Value on 4/1/17 -------------------------------------------------------------------------------- Ending Account Value $1,025.10 $1,021.50 $1,027.70 (after expenses) on 9/30/17 -------------------------------------------------------------------------------- Expenses Paid $ 5.69 $ 9.48 $ 4.32 During Period* -------------------------------------------------------------------------------- * Expenses are equal to the Fund's annualized net expense ratio of 1.12%, 1.87%, and 0.85% for Class A, Class C, and Class Y shares, respectively, multiplied by the average account value over the period, multiplied by 183/365 (to reflect the one-half year period). Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 15 Hypothetical Example for Comparison Purposes The table below provides information about hypothetical account values and hypothetical expenses based on the Fund's actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the Fund's actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. You may use this information to compare the ongoing costs of investing in the Fund and other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other funds. Please note that the expenses shown in the tables are meant to highlight your ongoing costs only and do not reflect any transaction costs, such as sales charges (loads) that are charged at the time of the transaction. Therefore, the table below is useful in comparing ongoing costs only and will not help you determine the relative total costs of owning different funds. In addition, if these transaction costs were included, your costs would have been higher. Expenses Paid on a $1,000 Investment in Pioneer Dynamic Credit Fund Based on a hypothetical 5% return per year before expenses, reflecting the period from April 1, 2017, through September 30, 2017. -------------------------------------------------------------------------------- Share Class A C Y -------------------------------------------------------------------------------- Beginning Account $1,000.00 $1,000.00 $1,000.00 Value on 4/1/17 -------------------------------------------------------------------------------- Ending Account Value $1,019.45 $1,015.69 $1,020.81 (after expenses) on 9/30/17 -------------------------------------------------------------------------------- Expenses Paid $5.67 $ 9.45 $ 4.31 During Period* -------------------------------------------------------------------------------- * Expenses are equal to the Fund's annualized net expense ratio of 1.12%, 1.87%, and 0.85% for Class A, Class C, and Class Y shares, respectively, multiplied by the average account value over the period, multiplied by 183/365 (to reflect the one-half year period). 16 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 Schedule of Investments | 9/30/17 (unaudited) ------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($)(j) Rate (a) Spread (b) Value ------------------------------------------------------------------------------------------------------------- UNAFFILIATED ISSUERS -- 96.6% CONVERTIBLE CORPORATE BOND -- 0.0%+ MATERIALS -- 0.0%+ Steel -- 0.0%+ EUR 79,012 New World Resources NV, 4.0%, 10/7/20 (144A) (4.0% cash, 8.0% PIK) (PIK) $ 9 ------------------------------------------------------------------------------------------------------------- TOTAL CONVERTIBLE CORPORATE BOND (Cost $70,205) $ 9 ------------------------------------------------------------------------------------------------------------- CONVERTIBLE PREFERRED STOCKS -- 1.0% BANKS -- 1.0% Diversified Banks -- 1.0% 900 Bank of America Corp., 7.25% (Perpetual) $ 1,171,323 1,530 Wells Fargo & Co., 7.5% (Perpetual) 2,011,950 ------------- $ 3,183,273 ------------- Total Banks $ 3,183,273 ------------------------------------------------------------------------------------------------------------- TOTAL CONVERTIBLE PREFERRED STOCKS (Cost $3,120,105) $ 3,183,273 ------------------------------------------------------------------------------------------------------------- ------------------------------------------------------------------------------------------------------------- Shares ------------------------------------------------------------------------------------------------------------- COMMON STOCK -- 0.0%+ CAPITAL GOODS -- 0.0%+ Industrial Machinery -- 0.0%+ 3,071 Liberty Tire Recycling LLC (f)(g) $ 31 ------------------------------------------------------------------------------------------------------------- TOTAL COMMON STOCK (Cost $31) $ 31 ------------------------------------------------------------------------------------------------------------- ------------------------------------------------------------------------------------------------------------- Principal Amount ($)(j) ------------------------------------------------------------------------------------------------------------- ASSET BACKED SECURITIES -- 2.7% CONSUMER SERVICES -- 0.1% Hotels, Resorts & Cruise Lines -- 0.1% 255,242 Westgate Resorts 2014-1 LLC, 5.5%, 12/20/26 (144A) $ 259,148 ------------- Total Consumer Services $ 259,148 ------------------------------------------------------------------------------------------------------------- BANKS -- 2.6% Thrifts & Mortgage Finance -- 2.6% 1,200,000 Ascentium Equipment Receivables 2016-2 Trust, 6.79%, 10/10/24 (144A) $ 1,259,098 499,993 Axis Equipment Finance Receivables III LLC, 5.27%, 5/20/20 (144A) 486,953 500,000 Conn Funding II LP, 5.11%, 2/15/20 (144A) 503,327 680,000 Engs Commercial Finance Trust 2016-1, 5.22%, 1/22/24 (144A) 669,093 The accompanying notes are an integral part of these financial statements. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 17 Schedule of Investments | 9/30/17 (unaudited) (continued) ------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($)(j) Rate (a) Spread (b) Value ------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 1,800,000 Four Seas LP, 5.927%, 8/28/27 (144A) $ 1,800,000 145,365 7.78 GE Mortgage Services LLC, Variable Rate Note, 3/25/27 69,185 20,547 GLC Trust 2013-1, 3.0%, 7/15/21 (144A) 20,239 175,000 InSite Issuer LLC Class C Series 16-1A, 7.5%, 11/15/46 179,714 710,500 Navitas Equipment Receivables LLC 2015-1, 5.75%, 7/15/21 (144A) 705,763 178,773 RASC Series 2003-KS5 Trust, 4.96%, 7/25/33 (Step) 181,023 24,735 6.55 Security National Mortgage Loan Trust 2007-1, Variable Rate Note, 4/25/37 (144A) 24,673 1,377,680 Solarcity Lmc Series VI LLC, 4.8%, 9/21/48 (144A) 1,394,024 998,564 VOLT XXV LLC, 4.5%, 6/26/45 (Step) (144A) 986,979 ------------- $ 8,280,071 ------------- Total Banks $ 8,280,071 ------------------------------------------------------------------------------------------------------------- TOTAL ASSET BACKED SECURITIES (Cost $8,534,750) $ 8,539,219 ------------------------------------------------------------------------------------------------------------- COLLATERALIZED MORTGAGE OBLIGATIONS -- 5.2% BANKS -- 5.1% Thrifts & Mortgage Finance -- 5.1% 69,954 3.26 Bear Stearns ALT-A Trust 2003-3, Variable Rate Note, 10/25/33 $ 69,566 75,351 5.21 Bear Stearns Commercial Mortgage Securities Trust 2005-PWR7, Variable Rate Note, 2/11/41 75,289 1,600,000 5.28 Bear Stearns Commercial Mortgage Securities Trust 2005-TOP20, Variable Rate Note, 10/12/42 1,456,000 1,000,000 3.21 Citigroup Commercial Mortgage Trust 2014-GC23 REMICS, Variable Rate Note, 7/12/47 (144A) 643,948 400,000 Citigroup Commercial Mortgage Trust 2016-SMPL, 4.509%, 9/10/31 408,353 715,000 6.05 COBALT CMBS Commercial Mortgage Trust 2007-C3, Variable Rate Note, 5/15/46 713,394 220,000 6.05 COBALT CMBS Commercial Mortgage Trust 2007-C3, Variable Rate Note, 5/15/46 155,793 343,313 5.10 Credit Suisse First Boston Mortgage Securities Corp., Variable Rate Note, 8/15/38 342,874 The accompanying notes are an integral part of these financial statements. 18 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 ------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($)(j) Rate (a) Spread (b) Value ------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 2,050,000 5.10 Credit Suisse First Boston Mortgage Securities Corp., Variable Rate Note, 8/15/38 $ 1,845,482 500,000 3.74 CSAIL 2015-C4 Commercial Mortgage Trust REMICS, Variable Rate Note, 11/15/48 437,481 289,714 5.48 CSFB Mortgage-Backed Pass-Through Certificates Series 2003-17, Variable Rate Note, 6/25/33 3 240,708 Global Mortgage Securitization, Ltd., 5.25%, 11/25/32 (144A) 111,315 89,897 Global Mortgage Securitization, Ltd., 5.25%, 11/25/32 (144A) 8,728 370,569 Global Mortgage Securitization, Ltd., 5.25%, 4/25/32 (144A) 351,597 75,568 Global Mortgage Securitization, Ltd., 5.25%, 4/25/32 (144A) 21,493 570,000 5.00 GMAT 2013-1 Trust, Variable Rate Note, 8/25/53 492,615 533,692 5.13 1M LIBOR+ GS Mortgage Securities Trust 2014-GSFL, 390bps Floating Rate Note, 7/15/31 (144A) 534,967 53,864 Homeowner Assistance Program Reverse Mortgage Loan Trust 2013-RM1, 4.0%, 5/26/53 (144A) 53,568 1,850,000 7.46 1M LIBOR+ JP Morgan Chase Commercial Mortgage 622.45bps Securities Trust 2014-CBM MZ, Floating Rate Note, 10/15/19 (144A) 1,855,863 300,000 3.22 JPMDB Commercial Mortgage Securities Trust 2016-C4, Variable Rate Note, 12/15/49 (144A) 232,000 527,267 4.00 PNMR+ La Hipotecaria Panamanian Mortgage -125bps Trust 2007-1, Floating Rate Note, 12/23/36 (144A) 516,722 163,024 Merrill Lynch Mortgage Investors Trust Series 2006-AF1, 5.75%, 8/25/36 123,094 300,000 3.00 Morgan Stanley Capital I Trust 2016-BNK2, Variable Rate Note, 11/15/49 (144A) 239,203 500,000 Morgan Stanley Capital I Trust 2016-UBS9, 3.0%, 3/15/49 (144A) 398,990 1,400,000 3.46 3M LIBOR+ Octagon Investment Partners XVII, Ltd., 215bps Floating Rate Note, 10/25/25 (144A) 1,400,433 430,390 ORES 2014-LV3 LLC, 6.0%, 3/27/24 (144A) 430,390 1,525,000 N/A 1M LIBOR+ Starwood Waypoint Homes 2017-1 Trust, 260bps Floating Rate Note, 1/17/35 (144A) 1,510,513 1,000,000 Tricon American Homes 2017-SFR1 Trust, 5.151%, 9/17/34 (144A) 992,389 750,000 Wells Fargo Commercial Mortgage Trust 2016-BNK1, 3.0%, 8/15/49 (144A) 601,680 The accompanying notes are an integral part of these financial statements. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 19 Schedule of Investments | 9/30/17 (unaudited) (continued) ------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($)(j) Rate (a) Spread (b) Value ------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 200,000 4.49 WFRBS Commercial Mortgage Trust 2013-C12, Variable Rate Note, 3/15/48 (144A) $ 187,178 ------------- $ 16,210,921 ------------- Total Banks $ 16,210,921 ------------------------------------------------------------------------------------------------------------- Government -- 0.1% 377,805 5.63 1M LIBOR+ FREMF Mortgage Trust 2015-KLSF REMICS, 440bps Floating Rate Note, 11/25/22 (144A) $ 381,765 ------------- Total Government $ 381,765 ------------------------------------------------------------------------------------------------------------- TOTAL COLLATERALIZED MORTGAGE OBLIGATIONS (Cost $17,396,009) $ 16,592,686 ------------------------------------------------------------------------------------------------------------- CORPORATE BONDS -- 50.4% ENERGY -- 8.5% Oil & Gas Exploration & Production -- 1.2% 1,800,000 Whiting Petroleum Corp., 5.0%, 3/15/19 $ 1,800,540 565,000 WPX Energy, Inc., 5.25%, 9/15/24 566,412 1,216,000 WPX Energy, Inc., 7.5%, 8/1/20 1,322,400 ------------- $ 3,689,352 ------------------------------------------------------------------------------------------------------------- Oil & Gas Refining & Marketing -- 0.9% 2,940,000 EnLink Midstream Partners LP, 4.15%, 6/1/25 $ 2,963,724 ------------------------------------------------------------------------------------------------------------- Oil & Gas Storage & Transportation -- 6.4% 2,575,000 Boardwalk Pipelines LP, 4.95%, 12/15/24 $ 2,740,504 1,965,000 Cheniere Corpus Christi Holdings LLC, 5.875%, 3/31/25 2,114,831 2,150,000 Cheniere Energy Partners LP, 5.25%, 10/1/25 (144A) 2,198,375 2,690,000 Energy Transfer Equity LP, 5.5%, 6/1/27 2,831,225 1,400,000 Genesis Energy LP, 6.75%, 8/1/22 1,431,500 750,000 Kinder Morgan, Inc. Delaware, 5.3%, 12/1/34 783,020 1,755,000 Kinder Morgan, Inc. Delaware, 5.55%, 6/1/45 1,890,871 1,450,000 ONEOK, Inc., 6.875%, 9/30/28 1,687,481 2,200,000 Plains All American Pipeline LP, 4.65%, 10/15/25 2,265,607 2,150,000 Williams Partners LP, 6.3%, 4/15/40 2,574,935 ------------- $ 20,518,349 ------------- Total Energy $ 27,171,425 ------------------------------------------------------------------------------------------------------------- MATERIALS -- 1.6% Paper Packaging -- 0.6% 1,675,000 Sealed Air Corp., 5.5%, 9/15/25 (144A) $ 1,842,500 ------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 20 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 ------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($)(j) Rate (a) Spread (b) Value ------------------------------------------------------------------------------------------------------------- Steel -- 1.0% 2,010,000 ArcelorMittal, 6.0%, 3/1/21 $ 2,205,975 1,000,000 Commercial Metals Co., 4.875%, 5/15/23 1,045,000 ------------- $ 3,250,975 ------------- Total Materials $ 5,093,475 ------------------------------------------------------------------------------------------------------------- CAPITAL GOODS -- 2.5% Building Products -- 0.6% 1,845,000 Standard Industries, Inc., 5.375%, 11/15/24 (144A) $ 1,960,866 ------------------------------------------------------------------------------------------------------------- Construction & Engineering -- 0.7% 2,045,000 AECOM, 5.125%, 3/15/27 $ 2,114,019 ------------------------------------------------------------------------------------------------------------- Industrial Machinery -- 0.6% 1,875,000 Cleaver-Brooks, Inc., 8.75%, 12/15/19 (144A) $ 1,921,875 ------------------------------------------------------------------------------------------------------------- Trading Companies & Distributors -- 0.6% 1,010,000 United Rentals North America, Inc., 4.625%, 10/15/25 $ 1,022,625 1,010,000 United Rentals North America, Inc., 4.875%, 1/15/28 1,015,050 ------------- $ 2,037,675 ------------- Total Capital Goods $ 8,034,435 ------------------------------------------------------------------------------------------------------------- COMMERCIAL SERVICES & SUPPLIES -- 0.7% Diversified Support Services -- 0.7% 2,080,000 Ritchie Bros Auctioneers, Inc., 5.375%, 1/15/25 (144A) $ 2,199,600 ------------- Total Commercial Services & Supplies $ 2,199,600 ------------------------------------------------------------------------------------------------------------- AUTOMOBILES & COMPONENTS -- 0.5% Tires & Rubber -- 0.5% 1,680,000 The Goodyear Tire & Rubber Co., 4.875%, 3/15/27 $ 1,729,526 ------------- Total Automobiles & Components $ 1,729,526 ------------------------------------------------------------------------------------------------------------- CONSUMER DURABLES & APPAREL -- 1.2% Homebuilding -- 1.2% 765,000 DR Horton, Inc., 5.75%, 8/15/23 $ 869,724 1,325,000 KB Home, 7.0%, 12/15/21 1,487,312 1,400,000 Taylor Morrison Communities, Inc., 5.875%, 4/15/23 (144A) 1,484,000 ------------- $ 3,841,036 ------------- Total Consumer Durables & Apparel $ 3,841,036 ------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 21 Schedule of Investments | 9/30/17 (unaudited) (continued) ------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($)(j) Rate (a) Spread (b) Value ------------------------------------------------------------------------------------------------------------- CONSUMER SERVICES -- 0.7% Casinos & Gaming -- 0.7% 2,000,000 International Game Technology Plc, 6.5%, 2/15/25 (144A) $ 2,247,500 ------------- Total Consumer Services $ 2,247,500 ------------------------------------------------------------------------------------------------------------- MEDIA -- 4.8% Broadcasting -- 0.9% 1,500,000 CCO Holdings LLC, 5.125%, 5/1/27 (144A) $ 1,520,625 1,275,000 CCO Holdings LLC, 5.5%, 5/1/26 (144A) 1,321,219 ------------- $ 2,841,844 ------------------------------------------------------------------------------------------------------------- Cable & Satellite -- 3.9% 2,105,000 Altice US Finance I Corp., 5.5%, 5/15/26 (144A) $ 2,220,122 2,485,000 CSC Holdings LLC, 5.5%, 4/15/27 (144A) 2,584,400 2,255,000 Hughes Satellite Systems Corp., 5.25%, 8/1/26 2,345,200 450,000 Sirius XM Radio, Inc., 5.0%, 8/1/27 (144A) 459,000 1,075,000 Sirius XM Radio, Inc., 5.375%, 7/15/26 (144A) 1,131,438 653,000 Time Warner Cable LLC, 4.125%, 2/15/21 678,044 2,800,000 Videotron, Ltd., 5.375%, 6/15/24 (144A) 3,038,000 ------------- $ 12,456,204 ------------- Total Media $ 15,298,048 ------------------------------------------------------------------------------------------------------------- FOOD, BEVERAGE & TOBACCO -- 2.4% Brewers -- 0.7% 2,020,000 Anheuser-Busch InBev Finance, Inc., 2.65%, 2/1/21 $ 2,052,806 ------------------------------------------------------------------------------------------------------------- Packaged Foods & Meats -- 1.2% 690,000 JBS USA LUX SA, 8.25%, 2/1/20 (144A) $ 696,900 1,295,000 Marfrig Holdings Europe BV, 6.875%, 6/24/19 (144A) 1,333,850 1,690,000 Post Holdings, Inc., 5.5%, 3/1/25 (144A) 1,753,375 ------------- $ 3,784,125 ------------------------------------------------------------------------------------------------------------- Tobacco -- 0.5% 1,515,000 Reynolds American, Inc., 4.85%, 9/15/23 $ 1,662,802 ------------- Total Food, Beverage & Tobacco $ 7,499,733 ------------------------------------------------------------------------------------------------------------- HEALTH CARE EQUIPMENT & SERVICES -- 5.0% Health Care Facilities -- 2.1% 3,340,000 HCA, Inc., 5.25%, 4/15/25 $ 3,611,375 1,740,000 Kindred Healthcare, Inc., 8.0%, 1/15/20 1,709,011 The accompanying notes are an integral part of these financial statements. 22 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 ------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($)(j) Rate (a) Spread (b) Value ------------------------------------------------------------------------------------------------------------- Health Care Facilities -- (continued) 1,225,000 RegionalCare Hospital Partners Holdings, Inc., 8.25%, 5/1/23 (144A) $ 1,287,781 ------------- $ 6,608,167 ------------------------------------------------------------------------------------------------------------- Managed Health Care -- 2.2% 3,140,000 Centene Corp., 4.75%, 1/15/25 $ 3,257,750 1,780,000 Molina Healthcare, Inc., 5.375%, 11/15/22 1,834,468 1,750,000 WellCare Health Plans, Inc., 5.25%, 4/1/25 1,841,875 ------------- $ 6,934,093 ------------------------------------------------------------------------------------------------------------- Health Care Technology -- 0.7% 2,150,000 Quintiles IMS, Inc., 5.0%, 10/15/26 (144A) $ 2,279,000 ------------- Total Health Care Equipment & Services $ 15,821,260 ------------------------------------------------------------------------------------------------------------- PHARMACEUTICALS, BIOTECHNOLOGY & LIFE SCIENCES -- 0.6% Pharmaceuticals -- 0.6% 605,000 Valeant Pharmaceuticals International, Inc., 6.5%, 3/15/22 (144A) $ 639,788 1,250,000 Valeant Pharmaceuticals International, Inc., 7.0%, 3/15/24 (144A) 1,334,488 ------------- $ 1,974,276 ------------- Total Pharmaceuticals, Biotechnology & Life Sciences $ 1,974,276 ------------------------------------------------------------------------------------------------------------- BANKS -- 6.9% Diversified Banks -- 6.9% EUR 1,000,000 8.88 Banco Bilbao Vizcaya Argentaria SA, Variable Rate Note (Perpetual) $ 1,372,602 1,445,000 6.30 3M LIBOR+ Bank of America Corp., Floating Rate 455.3bps Note (Perpetual) 1,632,850 2,605,000 7.62 USSW5+ BNP Paribas SA, Floating Rate Note 631.4bps (Perpetual) (144A) 2,862,244 2,640,000 BPCE SA, 4.875%, 4/1/26 (144A) 2,803,540 EUR 1,200,000 6.62 Cooperatieve Rabobank UA, Variable Rate Note (Perpetual) 1,598,637 833,000 6.12 Danske Bank AS, Variable Rate Note (Perpetual) 893,956 1,780,000 6.00 USISDA05+ HSBC Holdings Plc, Floating Rate 374.6bps Note (Perpetual) 1,861,702 2,685,000 6.50 USSW5+ ING Groep NV, Floating Rate Note, 444.6bps 12/29/49 2,876,440 ARS 8,152,000 Letras Banco Central Argentina, 4/18/18 (c) 409,146 1,300,000 8.62 USSW5+ Royal Bank of Scotland Group Plc, Floating 759.8bps Rate Note (Perpetual) 1,441,375 1,200,000 7.38 USSW5+ Societe Generale SA, Floating Rate Note 623.8bps (Perpetual) (144A) 1,299,000 The accompanying notes are an integral part of these financial statements. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 23 Schedule of Investments | 9/30/17 (unaudited) (continued) ------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($)(j) Rate (a) Spread (b) Value ------------------------------------------------------------------------------------------------------------- Diversified Banks -- (continued) 1,400,000 6.00 Swedbank AB, Variable Rate Note (Perpetual) $ 1,485,554 EUR 1,055,000 9.25 UniCredit S.p.A., Variable Rate Note (Perpetual) 1,447,539 ------------- $ 21,984,585 ------------- Total Banks $ 21,984,585 ------------------------------------------------------------------------------------------------------------- DIVERSIFIED FINANCIALS -- 3.3% Other Diversified Financial Services -- 0.4% 1,000,000 Fixed Income Trust Series 2013-A, 10/15/97 (Step) (144A) (c)(f)(g) $ 1,077,100 100,000 0.00 Tiers Trust, Variable Rate Note, 10/15/97 (144A) (f)(g) 128,968 ------------- $ 1,206,068 ------------------------------------------------------------------------------------------------------------- Specialized Finance -- 1.0% 1,120,000 Nationstar Mortgage LLC, 6.5%, 6/1/22 $ 1,150,800 825,000 Nationstar Mortgage LLC, 6.5%, 7/1/21 841,500 1,330,000 Park Aerospace Holdings, Ltd., 5.25%, 8/15/22 (144A) 1,383,200 ------------- $ 3,375,500 ------------------------------------------------------------------------------------------------------------- Consumer Finance -- 0.4% INR 80,340,000 International Finance Corp., 6.3%, 11/25/24 $ 1,251,638 ------------------------------------------------------------------------------------------------------------- Investment Banking & Brokerage -- 0.8% 2,290,000 UBS AG, 7.625%, 8/17/22 $ 2,699,338 ------------------------------------------------------------------------------------------------------------- Diversified Capital Markets -- 0.7% 1,955,000 7.12 Credit Suisse Group AG, Variable Rate Note (Perpetual) $ 2,108,956 ------------- Total Diversified Financials $ 10,641,500 ------------------------------------------------------------------------------------------------------------- INSURANCE -- 3.8% Multi-line Insurance -- 0.8% 2,500,000 Liberty Mutual Group, Inc., 4.25%, 6/15/23 (144A) $ 2,670,260 ------------------------------------------------------------------------------------------------------------- Reinsurance -- 3.0% 500,000 Arlington Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 8/31/16 (d)(e)(f) $ 24,300 250,000 4.49 3M LIBOR+ Atlas IX Capital DAC, Floating Rate Note, 325bps 1/17/19 (Cat Bond) (144A) 253,500 500,000 Berwick Segregated Account (Artex SAC Ltd.), Variable Rate Note, 1/22/16 (d)(e)(f) 15,000 500,000 Carnoustie 2016-N,Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 11/30/20 (d)(e)(f) 54,100 The accompanying notes are an integral part of these financial statements. 24 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 ------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($)(j) Rate (a) Spread (b) Value ------------------------------------------------------------------------------------------------------------- Reinsurance -- (continued) 500,000 Carnoustie Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 11/30/21 (d)(e)(f) $ 417,700 1,500,000 Carnoustie Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 2/19/16 (d)(e)(f) 30,600 250,000 Cypress 2017 Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 1/10/18 (d)(e)(f) 215,525 250,000 7.38 6M LIBOR+ Galilei Re, Ltd., Floating Rate Note, 625bps 1/8/20 (Cat Bond) (144A) 234,125 400,000 6.38 6M LIBOR+ Galilei Re, Ltd., Floating Rate Note, 525bps 1/8/20 (Cat Bond) (144A) 388,320 250,000 9.13 6M LIBOR+ Galilei Re, Ltd., Floating Rate Note, 800bps 1/8/20 (Cat Bond) (144A) 202,675 52,500 1.54 T-BILL 3M + Gator Re, Ltd., Floating Rate Note, 50bps 1/9/20 (Cat Bond) (144A) 1 250,000 3.31 T-BILL 3M + Golden State Re II, Ltd., Floating Rate 220bps Note, 1/8/19 (Cat Bond) (144A) 249,800 2,000,000 Gullane Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 11/30/21 (d)(e)(f) 1,960,400 250,000 11.15 6M LIBOR+ Kilimanjaro II Re, Ltd., Floating Rate Note, 1000bps 4/20/21 (Cat Bond) (144A) 149,600 350,000 5.51 T-BILL 3M+ Kilimanjaro Re, Ltd., Floating Rate Note, 450bps 4/30/18 (Cat Bond) (144A) 318,745 400,000 5.76 T-BILL 3M+ Kilimanjaro Re, Ltd., Floating Rate Note, 475bps 4/30/18 (Cat Bond) (144A) 399,000 250,000 0.00 Limestone Re, Ltd., Floating Rate Note 8/31/21 (Cat Bond) 221,775 250,000 Lorenz Re, Variable Rate Notes, 3/31/20 (d)(e)(f) 235,550 2,000,000 Pangaea Re, Series 2015-1, Principal at Risk Notes, 2/1/19 (d)(e)(f) 9,000 2,000,000 Pangaea Re, Series 2015-2, Principal at Risk Notes, 11/30/19 (d)(e)(f) 20,800 1,000,000 Pangaea Re, Variable Rate Notes, 2/1/20 (d)(e)(f) 66,100 1,000,000 Pangaea Re, Variable Rate Notes, 11/30/21 (d)(e)(f) 955,800 700,000 Prestwick Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 7/1/16 (d)(e)(f) 11,900 250,000 6.40 T-BILL 3M+ Residential Reinsurance 2016, Ltd., Floating 537bps Rate Note, 12/6/23 (Cat Bond) (144A) 246,850 250,000 Resilience Re, Ltd., Varible Rate Notes, 1/12/18 (d)(e)(f) 236,325 The accompanying notes are an integral part of these financial statements. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 25 Schedule of Investments | 9/30/17 (unaudited) (continued) ------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($)(j) Rate (a) Spread (b) Value ------------------------------------------------------------------------------------------------------------- Reinsurance -- (continued) 250,000 4.50 Resilience Re, Ltd., Variable Rate Note, 1/9/19 (d)(e)(f) $ 250,000 AUD 300,000 Rw0009 Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 1/10/18 (d)(e)(f) 17,057 500,000 Silverton Re, Ltd., Variable Rate Notes, 9/18/18 (144A) (d)(e)(f) 14,000 1,200,000 St. Andrews Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 1/22/16 (d)(e)(f) 23,640 217,248 St. Andrews Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 6/1/19 (d)(e)(f) 199,347 250,000 Sunningdale Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 1/16/18 (d)(e)(f) 243,025 250,000 4.68 ZERO+ Ursa Re, Ltd., Floating Rate Note, 400bps 12/10/19 (Cat Bond) (144A) 251,200 1,250,000 Versutus 2016, Class A-1, Variable Rate Notes, 11/30/20 (d)(e)(f) 53,250 1,500,000 Versutus, Variable Rate Notes, 11/30/21 (d)(e)(f) 1,485,300 ------------- $ 9,454,310 ------------- Total Insurance $ 12,124,570 ------------------------------------------------------------------------------------------------------------- SOFTWARE & SERVICES -- 0.5% IT Consulting & Other Services -- 0.5% 1,500,000 Dell International LLC, 4.42%, 6/15/21 (144A) $ 1,574,873 ------------- Total Software & Services $ 1,574,873 ------------------------------------------------------------------------------------------------------------- TECHNOLOGY HARDWARE & EQUIPMENT -- 0.4% Communications Equipment -- 0.4% 1,700,000 Avaya, Inc., 4/1/19 (144A) (c) $ 1,436,500 ------------- Total Technology Hardware & Equipment $ 1,436,500 ------------------------------------------------------------------------------------------------------------- SEMICONDUCTORS & SEMICONDUCTOR EQUIPMENT -- 0.4% Semiconductor Equipment -- 0.4% 1,250,000 Sensata Technologies BV, 5.0%, 10/1/25 (144A) $ 1,317,562 ------------- Total Semiconductors & Semiconductor Equipment $ 1,317,562 ------------------------------------------------------------------------------------------------------------- TELECOMMUNICATION SERVICES -- 3.1% Integrated Telecommunication Services -- 2.4% 3,555,000 CenturyLink, Inc., 5.8%, 3/15/22 $ 3,543,268 1,400,000 Level 3 Financing, Inc., 5.375%, 5/1/25 1,439,375 1,335,000 Sprint Capital Corp., 6.875%, 11/15/28 1,495,200 The accompanying notes are an integral part of these financial statements. 26 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 ------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($)(j) Rate (a) Spread (b) Value ------------------------------------------------------------------------------------------------------------- Integrated Telecommunication Services -- (continued) 1,175,000 Verizon Communications, Inc., 2.625%, 2/21/20 $ 1,194,347 ------------- $ 7,672,190 ------------------------------------------------------------------------------------------------------------- Wireless Telecommunication Services -- 0.7% 1,400,000 T-Mobile USA, Inc., 6.625%, 4/1/23 $ 1,473,528 300,000 Unison Ground Lease Funding LLC, 5.78%, 3/16/43 (144A) 297,848 400,000 WCP Issuer llc, 6.657%, 8/15/20 (144A) 414,033 ------------- $ 2,185,409 ------------- Total Telecommunication Services $ 9,857,599 ------------------------------------------------------------------------------------------------------------- UTILITIES -- 3.5% Electric Utilities -- 0.5% 1,190,000 8.13 USSW5+ Enel S.p.A., Floating Rate Note, 9/24/73 588bps (144A) $ 1,441,388 118,000 NextEra Energy Operating Partners LP, 4.5%, 9/15/27 (144A) 120,212 ------------- $ 1,561,600 ------------------------------------------------------------------------------------------------------------- Gas Utilities -- 1.4% 2,715,000 DCP Midstream Operating LP, 3.875%, 3/15/23 $ 2,660,700 300,000 DCP Midstream Operating LP, 5.6%, 4/1/44 279,750 1,500,000 Ferrellgas LP, 6.75%, 6/15/23 1,447,500 ------------- $ 4,387,950 ------------------------------------------------------------------------------------------------------------- Independent Power Producers & Energy Traders -- 1.6% 2,145,000 Calpine Corp., 5.75%, 1/15/25 $ 2,024,344 1,085,000 Dynegy, Inc., 8.125%, 1/30/26 (144A) 1,117,550 1,910,000 NRG Energy, Inc., 6.625%, 1/15/27 2,000,725 ------------- $ 5,142,619 ------------- Total Utilities $ 11,092,169 ------------------------------------------------------------------------------------------------------------- TOTAL CORPORATE BONDS (Cost $155,008,709) $ 160,939,672 ------------------------------------------------------------------------------------------------------------- U.S. GOVERNMENT AND AGENCY OBLIGATIONS -- 16.1% 9,025,000 U.S. Treasury Bills, 10/12/17 (c) $ 9,022,683 6,090,000 U.S. Treasury Bills, 10/19/17 (c) 6,087,358 2,045,000 U.S. Treasury Bills, 10/26/17 (c) 2,043,724 1,500,000 U.S. Treasury Bills, 10/5/17 (c) 1,499,909 2,790,000 U.S. Treasury Bills, 11/2/17 (c) 2,787,694 7,700,000 U.S. Treasury Bonds, 4.5%, 2/15/36 9,904,426 The accompanying notes are an integral part of these financial statements. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 27 Schedule of Investments | 9/30/17 (unaudited) (continued) ------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($)(j) Rate (a) Spread (b) Value ------------------------------------------------------------------------------------------------------------- U.S. GOVERNMENT AND AGENCY OBLIGATIONS -- (continued) 1,665,000 1.22 USBMMY3M+ U.S. Treasury Note, Floating Rate 16.79bps Note, 10/31/17 $ 1,665,223 6,600,000 U.S. Treasury Notes, 1.125%, 6/30/21 6,447,375 11,900,000 U.S. Treasury Notes, 1.875%, 5/31/22 11,891,166 ------------- $ 51,349,558 ------------------------------------------------------------------------------------------------------------- TOTAL U.S. GOVERNMENT AND AGENCY OBLIGATIONS (Cost $51,363,989) $ 51,349,558 ------------------------------------------------------------------------------------------------------------- FOREIGN GOVERNMENT BONDS -- 1.6% ARS 10,040,000 Argentine Bonos del Tesoro, 15.5%, 10/17/26 $ 615,391 ARS 9,350,000 Argentine Bonos del Tesoro, 22.75%, 3/5/18 533,404 1,500,000 Ecuador Government International Bond, 7.95%, 6/20/24 1,483,125 EGP 21,400,000 Egypt Treasury Bills, 5/29/18 (c) 1,087,566 UYU 39,685,000 Uruguay Government International Bond, 9.875%, 6/20/22 (144A) 1,476,840 ------------- $ 5,196,326 ------------------------------------------------------------------------------------------------------------- TOTAL FOREIGN GOVERNMENT BONDS (Cost $5,119,331) $ 5,196,326 ------------------------------------------------------------------------------------------------------------- SENIOR FLOATING RATE LOAN INTERESTS -- 19.0%** ENERGY -- 0.3% Oil & Gas Exploration & Production -- 0.3% 800,000 8.81 LIBOR + Chesapeake Energy Corp., Class A Loan, 750 bps 8/17/21 $ 862,750 ------------- Total Energy $ 862,750 ------------------------------------------------------------------------------------------------------------- MATERIALS -- 1.6% Diversified Chemicals -- 0.3% 332,558 0.00 LIBOR + Tronox Blocked Borrower LLC, Blocked Dollar 300 bps Term Loan (First Lien), 9/14/24 $ 334,195 767,442 0.00 LIBOR + Tronox Finance LLC, Initial Dollar Term Loan 300 bps (First Lien), 9/14/24 771,219 ------------- $ 1,105,414 ------------------------------------------------------------------------------------------------------------- Construction Materials -- 0.3% 1,000,000 4.46 CD&R Waterworks Merger Sub LLC, Initial Term Loan, 7/21/24 $ 1,005,250 ------------------------------------------------------------------------------------------------------------- Metal & Glass Containers -- 0.6% 746,124 5.58 LIBOR + Coveris Holdings SA (f.k.a. Exopack 425 bps Holdings SA), USD Term B-1 Loan, 6/29/22 $ 745,425 The accompanying notes are an integral part of these financial statements. 28 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 ------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($)(j) Rate (a) Spread (b) Value ------------------------------------------------------------------------------------------------------------- Metal & Glass Containers -- (continued) 997,449 4.81 LIBOR + Tekni-Plex, Inc., Tranche B-1 Term Loan 350 bps (First Lien), 4/15/22 $ 998,903 ------------- $ 1,744,328 ------------------------------------------------------------------------------------------------------------- Paper Packaging -- 0.1% 199,000 6.83 LIBOR + Caraustar Industries, Inc., Refinancing Term 550 bps Loan, 3/9/22 $ 199,435 ------------------------------------------------------------------------------------------------------------- Steel -- 0.3% 994,987 4.07 LIBOR + Zekelman Industries, Inc., Term Loan, 275 bps 6/8/21 $ 999,962 ------------- Total Materials $ 5,054,389 ------------------------------------------------------------------------------------------------------------- CAPITAL GOODS -- 3.0% Aerospace & Defense -- 0.8% 925,000 2.75 LIBOR + MacDonald, Dettwiler and Associates, Ltd., 275 bps Term Loan B, 7/5/24 $ 926,569 750,000 0.00 StandardAero Aviation Holdings, Inc., Term Loan, 7/7/22 755,759 992,074 6.08 LIBOR + The SI Organization, Inc., Term Loan (First 475 bps Lien), 11/19/19 1,007,109 ------------- $ 2,689,437 ------------------------------------------------------------------------------------------------------------- Building Products -- 0.3% 898,626 4.33 LIBOR + Builders FirstSource, Inc., Refinancing Term 300 bps Loan, 2/29/24 $ 901,903 ------------------------------------------------------------------------------------------------------------- Industrial Conglomerates -- 0.6% 746,117 4.24 LIBOR + Filtration Group, Inc., Term Loan (First 300 bps Lien), 11/21/20 $ 752,568 995,000 4.58 LIBOR + Gates Global LLC, Initial B-1 Dollar Term 325 bps Loan, 3/30/24 1,000,428 ------------- $ 1,752,996 ------------------------------------------------------------------------------------------------------------- Construction & Farm Machinery & Heavy Trucks -- 0.3% 890,932 5.24 LIBOR + Navistar, Inc., Tranche B Term Loan, 400 bps 8/7/20 $ 898,913 ------------------------------------------------------------------------------------------------------------- Industrial Machinery -- 0.6% 577,058 4.31 LIBOR + Columbus Mckinnon Corp., Initial Term 300 bps Loan, 1/20/24 $ 580,838 1,307,718 5.48 LIBOR + NN, Inc., Tranche B Term Loan, 10/19/22 425 bps 1,310,170 ------------- $ 1,891,008 ------------------------------------------------------------------------------------------------------------- Trading Companies & Distributors -- 0.4% 1,308,438 3.98 LIBOR + Univar USA, Inc., Term B-2 Loan, 7/1/22 275 bps $ 1,314,674 ------------- Total Capital Goods $ 9,448,931 ------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 29 Schedule of Investments | 9/30/17 (unaudited) (continued) ------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($)(j) Rate (a) Spread (b) Value ------------------------------------------------------------------------------------------------------------- COMMERCIAL SERVICES & SUPPLIES -- 0.7% Environmental & Facilities Services -- 0.3% 1,000,000 4.58 LIBOR + Albany Molecular Research, Inc., Initial Term 325 bps Loan (First Lien), 7/28/24 $ 1,004,844 ------------------------------------------------------------------------------------------------------------- Diversified Support Services -- 0.4% 27,828 4.73 LIBOR + IAP Worldwide Services, Inc., Term Loan, 650 bps 7/18/19 $ 27,689 1,148,142 3.62 LIBOR + KAR Auction Services, Inc., Tranche B-4 225 bps Term Loan, 3/11/21 1,155,556 ------------- $ 1,183,245 ------------- Total Commercial Services & Supplies $ 2,188,089 ------------------------------------------------------------------------------------------------------------- TRANSPORTATION -- 0.3% Marine -- 0.3% 461,317 9.98 LIBOR + Commercial Barge Line Co., Initial Term 875 bps Loan, 11/6/20 $ 368,246 487,500 6.32 LIBOR + Navios Maritime Partners LP (Navios 500 bps Partners Finance (US) Inc.), Initial Term Loan, 9/14/20 486,891 ------------- $ 855,137 ------------- Total Transportation $ 855,137 ------------------------------------------------------------------------------------------------------------- AUTOMOBILES & COMPONENTS -- 0.5% Auto Parts & Equipment -- 0.5% 393,468 6.08 LIBOR + Electrical Components International, Inc., 475 bps Loan, 4/17/21 $ 396,542 372,281 4.98 LIBOR + Federal-Mogul Corporation, Tranche C 375 bps Term, 4/15/21 374,337 896,231 4.00 LIBOR + Tower Automotive Holdings USA LLC, Initial 275 bps Term Loan, 3/6/24 900,338 ------------- $ 1,671,217 ------------- Total Automobiles & Components $ 1,671,217 ------------------------------------------------------------------------------------------------------------- CONSUMER DURABLES & APPAREL -- 0.2% Leisure Products -- 0.2% 497,487 4.24 LIBOR + BRP US, Inc., Term B Loan, 6/30/23 300 bps $ 501,130 ------------- Total Consumer Durables & Apparel $ 501,130 ------------------------------------------------------------------------------------------------------------- CONSUMER SERVICES -- 3.1% Casinos & Gaming -- 0.5% 518,211 3.56 LIBOR + Eldorado Resorts, Inc., Term Loan, 225 bps 3/16/24 $ 518,319 997,500 4.51 LIBOR + Scientific Games International, Inc., Initial 325 bps Term B-4 Loan, 8/14/24 1,000,462 ------------- $ 1,518,781 ------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 30 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 ------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($)(j) Rate (a) Spread (b) Value ------------------------------------------------------------------------------------------------------------- Leisure Facilities -- 0.4% 1,122,572 7.50 PRIME + L.A. Fitness International, LLC, Tranche B 325 bps Term Loan (First Lien), 4/25/20 $ 1,134,149 ------------------------------------------------------------------------------------------------------------- Education Services -- 0.8% 815,553 5.74 LIBOR + Laureate Education, Inc., Series 2024 Term 450 bps Loan, 4/21/24 $ 819,800 1,826,875 5.24 LIBOR + McGraw-Hill Global Education Holdings LLC, 400 bps Term B Loan (First Lien), 5/2/22 1,797,378 ------------- $ 2,617,178 ------------------------------------------------------------------------------------------------------------- Specialized Consumer Services -- 1.4% 1,994,937 5.78 LIBOR + Allied Universal Holdco LLC, Initial Term Loan 375 bps (First Lien), 7/28/22 $ 1,995,144 997,500 6.33 LIBOR + Constellis Holdings LLC, Term B Loan (First 500 bps Lien), 4/18/24 995,006 994,859 5.48 LIBOR + Genex Holdings, Inc., Term B Loan (First 425 bps Lien), 5/22/21 991,128 498,744 5.05 LIBOR + Kuehg Corp., Term B-2 Loan, 8/13/22 375 bps 499,617 ------------- $ 4,480,895 ------------- Total Consumer Services $ 9,751,003 ------------------------------------------------------------------------------------------------------------- MEDIA -- 0.5% Broadcasting -- 0.2% 500,000 2.25 LIBOR + The E.W. Scripps Co., Term Loan B, 225 bps 8/16/24 $ 502,344 ------------------------------------------------------------------------------------------------------------- Movies & Entertainment -- 0.1% 496,154 3.74 LIBOR + Rovi Solutions Corp., Term B Loan, 250 bps 7/2/21 $ 498,413 ------------------------------------------------------------------------------------------------------------- Publishing -- 0.2% 744,375 4.58 LIBOR + Trader Corp., 2017 Refinancing Term Loan 325 bps (First Lien), 9/28/23 $ 744,375 ------------- Total Media $ 1,745,132 ------------------------------------------------------------------------------------------------------------- RETAILING -- 1.1% Department Stores -- 0.1% 493,631 5.57 LIBOR + JC Penney Corp., Inc., Term Loan (2016), 425 bps 6/10/23 $ 483,347 ------------------------------------------------------------------------------------------------------------- Home Improvement Retail -- 0.4% 1,181,112 4.50 LIBOR + Apex Tool Group LLC, Term Loan, 2/1/20 325 bps $ 1,149,615 ------------------------------------------------------------------------------------------------------------- Specialty Stores -- 0.3% 1,000,000 5.31 LIBOR + Staples, Inc., Closing Date Term Loan, 400 bps 8/15/24 $ 996,252 ------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 31 Schedule of Investments | 9/30/17 (unaudited) (continued) ------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($)(j) Rate (a) Spread (b) Value ------------------------------------------------------------------------------------------------------------- Automotive Retail -- 0.3% 865,918 4.98 LIBOR + CWGS Group LLC, Term Loan, 11/3/23 375 bps $ 871,438 ------------- Total Retailing $ 3,500,652 ------------------------------------------------------------------------------------------------------------- FOOD & STAPLES RETAILING -- 0.2% Food Retail -- 0.2% 621,235 4.32 LIBOR + Albertson's LLC, 2017-1 Term B-6 Loan, 300 bps 6/22/23 $ 598,160 ------------- Total Food & Staples Retailing $ 598,160 ------------------------------------------------------------------------------------------------------------- FOOD, BEVERAGE & TOBACCO -- 0.8% Packaged Foods & Meats -- 0.6% 968,906 4.01 LIBOR + Chobani, LLC (Chobani Idaho LLC), Closing 275 bps Date Term Loan (First Lien), 10/10/23 $ 973,347 1,000,000 5.48 LIBOR + Dole Food Co., Inc., Tranche B Term Loan, 425 bps 3/23/24 1,005,208 ------------- $ 1,978,555 ------------------------------------------------------------------------------------------------------------- Tobacco -- 0.2% 500,000 4.74 LIBOR + AI Aqua Zip Bidco Pty, Ltd., 2017 Incremental 350 bps Term Loan (First Lien), 12/13/23 $ 502,812 ------------- Total Food, Beverage & Tobacco $ 2,481,367 ------------------------------------------------------------------------------------------------------------- HOUSEHOLD & PERSONAL PRODUCTS -- 0.9% Household Products -- 0.3% 1,000,000 3.50 LIBOR + Alphabet Holding Co, Inc., Initial Term Loan 350 bps (First Lien), 8/15/24 $ 992,396 ------------------------------------------------------------------------------------------------------------- Personal Products -- 0.6% 498,750 5.16 LIBOR + Albea Beauty Holdings SA, 1st Lien Term 200 bps Loan B, 4/12/24 $ 499,062 1,489,969 4.74 LIBOR + Revlon Consumer Products Corp., Initial 350 bps Term B Loan, 7/22/23 1,339,692 ------------- $ 1,838,754 ------------- Total Household & Personal Products $ 2,831,150 ------------------------------------------------------------------------------------------------------------- HEALTH CARE EQUIPMENT & SERVICES -- 1.0% Health Care Supplies -- 0.5% 1 4.59 Immucor, Inc., Term Loan, 8/19/18 $ 1 997,500 4.58 LIBOR + Kinetic Concepts, Inc., Dollar Term Loan, 325 bps 2/1/24 994,695 497,500 4.24 LIBOR + Sterigenics-Nordion Holdings LLC, 300 bps Incremental Term Loan, 5/15/22 498,122 ------------- $ 1,492,818 ------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 32 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 ------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($)(j) Rate (a) Spread (b) Value ------------------------------------------------------------------------------------------------------------- Health Care Facilities -- 0.5% 20,149 4.81 LIBOR + Acadia Healthcare Co, Inc., Tranche B-1 350 bps Term Loan, 2/6/22 $ 20,366 498,718 3.98 LIBOR + CHS, Incremental 2021 Term H Loan, 275 bps 1/27/21 502,926 511,134 4.32 LIBOR + Concentra, Inc., Tranche B Term Loan 300 bps (First Lien), 5/8/22 509,147 550,000 4.32 LIBOR + Select Medical Corp., Tranche B Term 300 bps Loan, 2/13/24 551,874 ------------- $ 1,584,313 ------------------------------------------------------------------------------------------------------------- Managed Health Care -- 0.0%+ 18,817 10.25 LIBOR + MMM Holdings, Inc., Term Loan, 875 bps 10/9/17 (h) $ 18,441 13,680 10.25 LIBOR + MSO of Puerto Rico, Inc., MSO Term 875 bps Loan, 12/12/17 (h) 13,406 ------------- $ 31,847 ------------- Total Health Care Equipment & Services $ 3,108,978 ------------------------------------------------------------------------------------------------------------- DIVERSIFIED FINANCIALS -- 1.0% Other Diversified Financial Services -- 0.2% 623,268 3.56 LIBOR + Fly Funding II S.a.r.l., Term Loan, 8/9/19 225 bps $ 625,345 ------------------------------------------------------------------------------------------------------------- Specialized Finance -- 0.4% 994,060 3.98 LIBOR + Vistra Operations Co., LLC, Initial Term C 275 bps Loan, 8/4/23 $ 997,255 228,429 3.98 LIBOR + Vistra Operations Co., LLC, Initial Term 275 bps Loan, 8/4/23 229,163 ------------- $ 1,226,418 ------------------------------------------------------------------------------------------------------------- Investment Banking & Brokerage -- 0.3% 994,809 5.08 LIBOR + Duff & Phelps Corp., Initial Term Loan, 375 bps 4/23/20 $ 1,001,648 ------------------------------------------------------------------------------------------------------------- Diversified Capital Markets -- 0.1% 500,000 3.49 LIBOR + Outfront Media Capital LLC, Term Loan, 225 bps 3/10/24 $ 503,616 ------------- Total Diversified Financials $ 3,357,027 ------------------------------------------------------------------------------------------------------------- INSURANCE -- 0.6% Property & Casualty Insurance -- 0.6% 997,494 6.27 LIBOR + Acrisure LLC, Term B Loan (First Lien), 500 bps 11/3/23 $ 1,010,586 1,000,000 3.00 LIBOR + USI, Inc. New York, Term Loan B, 5/16/24 300 bps 998,125 ------------- $ 2,008,711 ------------- Total Insurance $ 2,008,711 ------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 33 Schedule of Investments | 9/30/17 (unaudited) (continued) ------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($)(j) Rate (a) Spread (b) Value ------------------------------------------------------------------------------------------------------------- REAL ESTATE -- 0.3% Specialized REIT -- 0.3% 994,987 4.24 LIBOR + Uniti Group, Inc., Shortfall Term Loan, 300 bps 10/24/22 $ 921,601 ------------- Total Real Estate $ 921,601 ------------------------------------------------------------------------------------------------------------- SOFTWARE & SERVICES -- 2.2% Internet Software & Services -- 0.3% 997,500 4.31 LIBOR + Rackspace Hosting, Inc., 2017 Refinancing 300 bps Term B Loan (First Lien), 11/3/23 $ 997,679 ------------------------------------------------------------------------------------------------------------- IT Consulting & Other Services -- 0.3% 900,000 3.48 LIBOR + Booz Allen Hamilton, Inc., New Refinancing 225 bps Tranche B Term Loan, 6/30/23 $ 905,962 ------------------------------------------------------------------------------------------------------------- Data Processing & Outsourced Services -- 0.4% 1,268,318 3.98 LIBOR + WEX, Inc., Term B-2 Loan, 7/1/23 275 bps $ 1,281,794 ------------------------------------------------------------------------------------------------------------- Application Software -- 0.5% 1,000,000 0.00 LIBOR + Applied Systems, Inc., Initial Term Loan 325 bps (First Lien), 9/19/24 $ 1,010,833 745,869 6.58 LIBOR + STG-Fairway Acquisitions, Inc., Term Loan 525 bps (First Lien), 6/30/22 727,222 ------------- $ 1,738,055 ------------------------------------------------------------------------------------------------------------- Systems Software -- 0.7% 1,160,344 3.81 LIBOR + MA Financeco LLC, Tranche B-2 Term 275 bps Loan, 11/20/21 $ 1,161,915 942,190 4.58 LIBOR + Sybil Software LLC, Initial Refinancing 325 bps Dollar Term Loan, 9/30/23 947,743 ------------- $ 2,109,658 ------------- Total Software & Services $ 7,033,148 ------------------------------------------------------------------------------------------------------------- TECHNOLOGY HARDWARE & EQUIPMENT -- 0.1% Electronic Components -- 0.1% 497,449 6.08 LIBOR + Mirion Technologies Finance LLC, Initial Term 475 bps Loan (First Lien), 1/26/22 $ 498,796 ------------- Total Technology Hardware & Equipment $ 498,796 ------------------------------------------------------------------------------------------------------------- TELECOMMUNICATION SERVICES -- 0.1% Integrated Telecommunication Services -- 0.1% 81,768 4.75 LIBOR + Securus Technologies Holdings, Inc., Initial 350 bps Term Loan (First Lien), 4/30/20 $ 82,547 299,250 4.06 LIBOR + SFR Group SA, USD TLB-11 Term Loan, 275 bps 6/22/25 298,806 ------------- $ 381,353 ------------- Total Telecommunication Services $ 381,353 ------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 34 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 ------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($)(j) Rate (a) Spread (b) Value ------------------------------------------------------------------------------------------------------------- UTILITIES -- 0.5% Electric Utilities -- 0.5% 686,396 6.34 LIBOR + APLP Holdings LP, Term Loan, 4/12/23 425 bps $ 693,547 981,515 4.99 LIBOR + TPF II Power, LLC, Term Loan, 10/2/21 375 bps 987,998 ------------- $ 1,681,545 ------------- Total Utilities $ 1,681,545 ------------------------------------------------------------------------------------------------------------- TOTAL SENIOR FLOATING RATE LOAN INTERESTS (Cost $60,725,106) $ 60,480,266 ------------------------------------------------------------------------------------------------------------- TEMPORARY CASH INVESTMENT -- 0.5% Repurchase Agreement -- 0.5% 1,660,000 $1,660,000 ScotiaBank, 1.05%, dated 9/29/17 plus accrued interest on 10/2/17 collateralized by the following: $1,538 Freddie Mac Giant, 4.5%, 5/1/47 $386,862 Federal National Mortgage Association, 3.0%, 12/1/40-7/1/47 $1,304,948 Government National Mortgage Association, 3.0%, 8/20/47 $ 1,660,000 ------------------------------------------------------------------------------------------------------------- TOTAL TEMPORARY CASH INVESTMENT (Cost $1,660,000) $ 1,660,000 ------------------------------------------------------------------------------------------------------------- ------------------------------------------------------------------------------------------------------------- Number of Strike Expiration Contracts Description Counterparty Notional Price Date ------------------------------------------------------------------------------------------------------------- PURCHASED OPTIONS -- 0.1% PUT OPTIONS -- 0.1% 53 S&P 500 Index Citigroup Global Markets, Inc. 116,759 $2,375 10/20/17 $ 9,010 1,329 Ishares IBOXX Citigroup Global USD High Yield Markets, Inc. 87,714 86 10/20/17 13,290 1,700 Ishares IBOXX Citigroup Global USD High Yield Markets, Inc. 96,900 85 11/17/17 27,200 61 S&P 500 Index Citigroup Global Markets, Inc. 128,283 2,325 11/17/17 34,770 1,695 Ishares IBOXX Citigroup Global USD High Yield Markets, Inc. 91,530 85 12/15/17 60,172 61 S&P 500 Index Citigroup Global Markets, Inc. 108,763 2,350 12/15/17 79,300 ------------- $ 223,742 ------------------------------------------------------------------------------------------------------------- TOTAL PUT OPTIONS (Premiums paid $629,949) $ 223,742 ------------------------------------------------------------------------------------------------------------- TOTAL INVESTMENT IN UNAFFILIATED ISSUERS -- 96.6% (Cost $303,628,184) $ 308,164,782 ------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 35 Schedule of Investments | 9/30/17 (unaudited) (continued) ------------------------------------------------------------------------------------------------------------- Change in Net Net Unrealized Realized Appreciation Shares Income Gain (Loss) (Depreciation) ------------------------------------------------------------------------------------------------------------- <s> <c> <c> <c> <c> AFFILIATED ISSUERS -- 2.7% CLOSED END FUND -- 2.7% INSURANCE -- 2.7% Property & Casualty Insurance -- 2.7% 875,286 Pioneer ILS Interval Fund (i) $-- $-- $609,729 $ 8,490,271 ------------------------------------------------------------------------------------------------------------- TOTAL CLOSED END FUND $ 8,490,271 ------------------------------------------------------------------------------------------------------------- TOTAL INVESTMENT IN AFFILIATED ISSUERS -- 2.7% (Cost $9,100,000) $ 8,490,271 ------------------------------------------------------------------------------------------------------------- ------------------------------------------------------------------------------------------------------------- Number of Strike Expiration Contracts Description Counterparty Notional Price Date ------------------------------------------------------------------------------------------------------------- WRITTEN OPTIONS -- (0.0)%+ PUT WRITTEN OPTIONS -- (0.0)+% (61) S&P 500 Index Citigroup Global Markets, Inc. (46,786) $ 2,200 12/15/17 $ (32,940) (1,695) Ishares IBOXX Citigroup Global USD High Yield Markets, Inc. (27,119) 81 12/15/17 (26,273) (61) S&P 500 Index Citigroup Global Markets, Inc. (51,666) 2,171 11/17/17 (12,810) (1,700) Ishares IBOXX Citigroup Global USD High Yield Markets, Inc. (28,899) 81 11/17/17 (12,750) (1,329) Ishares IBOXX Citigroup Global USD High Yield Markets, Inc. (14,619) 80 10/20/17 (5,316) (53) S&P 500 Index Citigroup Global Markets, Inc. (44,890) 2,225 10/20/17 (2,915) ------------- $ (93,004) ------------------------------------------------------------------------------------------------------------- TOTAL PUT WRITTEN OPTIONS (Premiums received $(213,979)) $ (93,004) ------------------------------------------------------------------------------------------------------------- OTHER ASSETS & LIABILITIES -- 0.7% $ 2,460,286 ------------------------------------------------------------------------------------------------------------- TOTAL NET ASSETS -- 100.0% $319,022,339 ============================================================================================================= BPS Basis Point. LIBOR London-Interbank Offer Rate. PNMR Panamanian Mortgage Reference Rate. T-BILL 3M 3 Month Treasury Bill Rate. USSW5 USD Swap Semi 30/360 5Yr. USBMMY3M US Treasury 3 Month Bill Money Market Yield. USISDA05 USD ICE Swap Rate 5Yr. ZERO Zero Constant Index. + Amount rounds to less than 0.1% or (0.1)%. REIT Real Estate Investment Trust. (Step) Bond issued with an initial coupon rate which converts to a higher rate at a later date. The accompanying notes are an integral part of these financial statements. 36 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 (Cat Bond) Catastrophe or event-linked bond. At September 30, 2017, the value of these securities amounted to $2,915,591 or 0.9% of total net assets. See Notes to Financial Statements -- Note 1I. (Perpetual) Security with no stated maturity date. REMICS Real Estate Mortgage Investment Conduits. (PIK) Represents a pay in kind security. (144A) Security is exempt from registration under Rule 144A of the Securities Act of 1933. Such securities may be resold normally to qualified institutional buyers in a transaction exempt from registration. At September 29, 2017, the value of these securities amounted to $78,345,396 or 24.6% of total net assets. ** Senior floating rate loan interests in which the Fund invests generally pay interest at rates that are periodically redetermined by reference to a base lending rate plus a premium. These base lending rates are generally (i) the lending rate offered by one or more major European banks, such as LIBOR (London InterBank Offered Rate), (ii) the prime rate offered by one or more major U.S. banks, (iii) the certificate of deposit or (iv) other base lending rates used by commercial lenders. The rate shown is the coupon rate at period end. (a) Debt obligation with a variable or floating interest rate. Rate shown is rate at period end. (b) Floating rate note. Reference index and spread shown at period end. (c) Security issued with a zero coupon. Income is earned through accretion of discount. (d) Structured reinsurance investment. At September 30, 2017, the value of these securities amounted to $6,538,719 or 2.1% of total net assets. See Notes to Financial Statements -- Note 1I. (e) Rate to be determined. (f) Securities that used significant unobservable inputs to determine their value. (g) Security is valued using fair value methods (other than prices supplied by independent pricing services or broker-dealers). See Notes to Financial Statements -- Note 1A. (h) Security is in default. (i) Affiliated fund managed by Amundi Pioneer Asset Management, Inc. (j) Principal amounts are denominated in U.S. Dollars unless otherwise noted: ARS Argentine Peso AUD Australian Dollar EGP Egyptian Pound EUR Euro INR Indian Rupee UYU Uruguayan Peso Purchases and sales of securities (excluding temporary cash investments) for the six months ended September 30, 2017 were as follows: -------------------------------------------------------------------------------- Purchases Sales -------------------------------------------------------------------------------- Long-Term U.S. Government $ 19,687,034 $ 1,353,073 Other Long-Term Securities 111,354,875 92,006,570 The Fund is permitted to engage in purchase and sale transactions ("cross trades") with certain Funds and accounts for which Amundi Pioneer Asset Management, Inc., formerly Pioneer Investment Management, Inc. (the "Adviser") serves as investment adviser, as set forth in Rule 17a-7 under the Investment Company Act of 1940, pursuant to procedures adopted by the Board of Trustees. Under these procedures, cross trades are effected at current market prices. The accompanying notes are an integral part of these financial statements. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 37 Schedule of Investments | 9/30/17 (unaudited) (continued) During the six months ended September 30, 2017, the Fund engaged in purchases and sales pursuant to these procedures amounting to $4,155,481 and $2,204,292, respectively, which resulted in a net realized loss of $13,395. SWAP CONTRACTS CREDIT DEFAULT SWAP AGREEMENTS -- BUY PROTECTION OVER THE COUNTER (OTC) ------------------------------------------------------------------------------------------------------------------------- Obligation Annual Unrealized Notional Reference/ Pay/ Fixed Expiration Premiums Appreciation/ Market Amount ($)(1) Counterparty Index Receive Rate Date (Received) (Depreciation) Value ------------------------------------------------------------------------------------------------------------------------- (3,750,000) Goldman China Pay 1.00% 12/20/22 $ (77,408) $ 8,370 $ (69,038) Sachs Government International International Bond (7,625,000) Goldman Republic Pay 1.00% 12/20/22 (113,479) 15,958 (97,521) Sachs of Korea International (3,775,000) Goldman Republic Pay 1.00% 12/20/22 (99,408) (16,263) (115,671) Sachs of Japan International ------------------------------------------------------------------------------------------------------------------------- $(290,295) $ 8,065 $(282,230) ========================================================================================================================= CREDIT DEFAULT SWAP AGREEMENTS -- SELL PROTECTION OVER THE COUNTER (OTC) ------------------------------------------------------------------------------------------------------------------------- Obligation Annual Premiums Unrealized Notional Reference/ Pay/ Fixed Expiration Paid Appreciation/ Market Amount ($)(1) Counterparty Index Receive Rate Date (Received) (Depreciation) Value ------------------------------------------------------------------------------------------------------------------------- 3,880,000 Goldman Markit CDX Receive 5.00% 12/20/17 $(454,688) $ 486,758 $ 32,070 Sachs North America International Investment Grade Index 1,450,000 JPMorgan Frontier Receive 5.00% 6/20/19 57,771 (141,882) (84,111) Communi- cations, Inc. 1,275,000 Barclays Windstream Receive 5.00% 6/20/18 (130,688) (44,596) (175,284) Bank Plc Services, Inc. 1,900,000 Goldman Ally Receive 5.00% 12/20/22 326,546 (2,696) 323,850 Sachs Financial, International Inc. ------------------------------------------------------------------------------------------------------------------------- $(201,059) $ 297,584 $ 96,525 ========================================================================================================================= (1) The notional amount is the maximum amount that a seller of credit protection would be obligated to pay upon occurrence of a credit event. The accompanying notes are an integral part of these financial statements. 38 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 CENTRALLY CLEARED CREDIT DEFAULT SWAP AGREEMENTS -- SELL PROTECTION --------------------------------------------------------------------------------------------------------------------------- Obligation Annual Unrealized Notional Reference/ Pay/ Fixed Expiration Premiums Appreciation/ Market Amount ($)(1) Exchange Index Receive Rate Date Paid (Depreciation) Value --------------------------------------------------------------------------------------------------------------------------- 9,250,000 Inter- Markit CDX Receive 5.00% 6/20/22 $1,195,509 $193,155 $ 1,388,664 continental ITRAXX Exchange Crossover Index 5,850,000 Chicago Markit CDX Receive 5.00% 6/20/22 417,617 41,925 459,542 Mercantile North America Exchange High Yield Index 21,000,000 Inter- Markit CDX Receive 5.00% 12/20/22 2,918,835 29,868 2,948,703 continental ITRAXX Exchange Europe Crossover Index 15,925,000 Chicago Markit CDX Receive 5.00% 12/20/22 1,180,043 89,622 1,269,665 Mercantile North America Exchange High Yield Index --------------------------------------------------------------------------------------------------------------------------- $5,712,004 $354,570 $ 6,066,574 =========================================================================================================================== TOTAL SWAP CONTRACTS (Premiums $5,220,650) $ 5,880,869 =========================================================================================================================== FUTURES CONTRACTS INDEX FUTURES CONTRACTS -------------------------------------------------------------------------------------------------------------- Number of Contracts Expiration Notional Market Unrealized Long Description Date Amount Value Depreciation -------------------------------------------------------------------------------------------------------------- 27 U.S. 2 Year Note 12/29/17 5,842,125 $ 5,823,984 $ (18,141) 224 U.S. 5 Year Note 12/29/17 26,554,611 26,320,000 (234,611) 26 U.S. 10 Year Note 12/29/17 3,534,203 3,492,531 (41,672) -------------------------------------------------------------------------------------------------------------- Total 35,930,939 $35,636,515 $(294,424) ============================================================================================================== -------------------------------------------------------------------------------------------------------------- Number of Contracts Expiration Notional Market Unrealized Short Description Date Amount Value Appreciation -------------------------------------------------------------------------------------------------------------- 17 U.S. Ultra Bond 12/19/17 2,807,125 $ 2,807,125 $ 70,125 -------------------------------------------------------------------------------------------------------------- Total Futures Contracts 33,123,814 $32,829,390 $(224,299) ============================================================================================================== The accompanying notes are an integral part of these financial statements. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 39 Schedule of Investments | 9/30/17 (unaudited) (continued) FORWARD CURRENCY CONTRACTS -------------------------------------------------------------------------------------------------------------- as follows: Unrealized Currency In Settlement Appreciation/ Purchased Exchange for Sold Deliver Counterparty Date Depreciation -------------------------------------------------------------------------------------------------------------- RUB 86,315,065 USD (1,455,566) Bank Of America NA 12/1/17 $ 27,671 KRW 3,130,720,762 USD (2,732,583) Bank Of America NA 10/10/17 1,157 USD 2,757,494 KRW (3,130,720,762) Bank Of America NA 10/10/17 23,753 USD 759,962 GBP (565,000) Brown Brothers 11/2/17 1,700 Harriman And Co. SEK 12,158,705 EUR (1,262,640) Citibank NA 10/10/17 716 New York NY JPY 333,090,000 USD (2,956,151) Citibank NA 10/16/17 5,894 New York NY USD 1,564,990 KRW (1,766,435,810) Citibank NA 12/21/17 21,018 New York NY USD 3,123,059 KRW (3,519,718,597) Citibank NA 12/21/17 46,610 New York NY PHP 67,009,690 USD (1,324,826) Goldman Sachs 11/3/17 (10,509) International USD 1,418,660 NZD (1,980,000) Goldman Sachs 10/5/17 (11,041) International EUR 1,276,349 USD (1,505,280) JPMorgan 10/10/17 3,364 Chase Bank NA USD 1,556,399 GBP (1,149,569) JPMorgan 10/20/17 14,353 Chase Bank NA IDR 39,795,398,862 THB (98,751,000) JPMorgan 11/27/17 (23,279) Chase Bank NA INR 91,085,433 USD (1,408,966) JPMorgan 12/5/17 (24,742) Chase Bank NA JPY 173,976,513 USD (1,569,669) JPMorgan 12/21/17 (17,310) Chase Bank NA USD 1,311,088 PHP (67,009,690) JPMorgan 11/3/17 (3,228) Chase Bank NA EUR 274,837 USD (331,024) State Street Bank 10/10/17 (6,166) And Trust Co. USD 301,019 EUR (264,300) State Street Bank 10/10/17 (11,384) And Trust Co. USD 4,451,177 EUR (3,784,715) State Street Bank 11/13/17 (30,688) And Trust Co. EUR 1,298,959 GBP (1,148,740) State Street Bank 10/20/17 (4,720) And Trust Co. JPY 345,832,318 USD (3,117,138) State Street Bank 12/21/17 (31,342) And Trust Co. USD 1,211,345 AUD (1,542,382) State Street Bank 11/3/17 2,596 And Trust Co. -------------------------------------------------------------------------------------------------------------- TOTAL FORWARD CURRENCY CONTRACTS $(25,577) ============================================================================================================== The accompanying notes are an integral part of these financial statements. 40 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 AUD Australian Dollar EUR Euro GBP Great British Pound INR Indian Rupee IDR Indonesian Rupiah JPY Japanese Yen NZD New Zealand Dollar PHP Philippine Peso RUB Russian Ruble KRW South Korean Won SEK Swedish Krona THB Thai Baht At September 30, 2017, the net unrealized appreciation on investments based on cost for federal income tax purposes of $317,734,855 was as follows: Aggregate gross unrealized appreciation for all investments in which there is an excess of value over tax cost $ 7,683,702 Aggregate gross unrealized depreciation for all investments in which there is an excess of tax cost over value (3,756,833) ----------- Net unrealized appreciation $ 3,926,869 =========== Various inputs are used in determining the value of the Fund's investments. These inputs are summarized in the three broad levels listed below. Level 1 - quoted prices in active markets for identical securities. Level 2 - other significant observable inputs (including quoted prices for similar securities, interest rates,prepayment speeds, credit risk, etc.) See Notes to Financial Statements -- Note 1A. Level 3 - significant unobservable inputs (including the Fund's own assumptions in determining fair value of investments) See Notes to Financial Statements -- Note 1A. The following is a summary of the inputs used as of September 30, 2017, in valuing the Fund's investments: ---------------------------------------------------------------------------------------------------------- Level 1 Level 2 Level 3 Total ---------------------------------------------------------------------------------------------------------- Convertible Corporate Bond $ -- $ 9 $ -- $ 9 Convertible Preferred Stocks 3,183,273 -- -- 3,183,273 Common Stocks -- -- 31 31 Asset Backed Securities -- 8,539,219 -- 8,539,219 Collateralized Mortgage Obligations -- 16,592,686 -- 16,592,686 Corporate Bonds Diversified Financials Other Diversified Financial Services -- -- 1,206,068 1,206,068 Insurance Reinsurance -- 2,693,816 6,760,494 9,454,310 All Other Corporate Bonds -- 150,279,294 -- 150,279,294 U.S. Government and Agency Obligations -- 51,349,558 -- 51,349,558 Foreign Government Bonds -- 5,196,326 -- 5,196,326 Senior Floating Rate Loan Interests -- 60,480,266 -- 60,480,266 Repurchase Agreement -- 1,660,000 -- 1,660,000 Put Options Purchased 223,742 -- -- 223,742 Closed-End Fund -- 8,490,271 -- 8,490,271 ---------------------------------------------------------------------------------------------------------- Total $ 3,407,015 $305,281,445 $ 7,966,593 $ 316,655,053 ========================================================================================================== The accompanying notes are an integral part of these financial statements. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 41 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------- Level 1 Level 2 Level 3 Total -------------------------------------------------------------------------------------------------------- Other Financial Instruments Net unrealized depreciation on futures contracts $(224,299) $ -- $ -- $ (224,299) Swap contracts, at value -- 5,880,869 -- 5,880,869 Net unrealized depreciation on forward foreign currency transactions -- (25,577) -- (25,577) Put options written (93,004) -- -- (93,004) -------------------------------------------------------------------------------------------------------- Total Other Financial Instruments $(317,303) $5,855,292 $ -- $5,537,989 ======================================================================================================== The following is a reconciliation of assets valued using significant unobservable inputs (Level 3): -------------------------------------------------------------------------------------------------------- Common Corporate Stocks Bonds Total -------------------------------------------------------------------------------------------------------- Balance as of 3/31/17 $ 31 $8,107,653 $8,107,684 Realized gain (loss)(1) -- -- -- Change in unrealized appreciation (depreciation)(2) -- (608,339) (608,339) Purchases -- 500,000 500,000 Sales -- (32,752) (32,752) Transfers in to Level 3* -- -- -- Transfers out of Level 3* -- -- -- -------------------------------------------------------------------------------------------------------- Balance as of 9/30/17 $ 31 $7,966,562 $7,966,593 ======================================================================================================== (1) Realized gain (loss) on these securities is included in the net realized gain (loss) from investments in the Statement of Operations. (2) Unrealized appreciation (depreciation) on these securities is included in the change in unrealized appreciation (depreciation) on investments in the Statement of Operations. * Transfers are calculated on the beginning of period values. During the six months ended September 30, 2017, there were no transfers between Levels 1, 2 and 3. Net change in unrealized appreciation (depreciation) of investments still held as of 9/30/17 $(606,889) ========= The accompanying notes are an integral part of these financial statements. 42 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 Statement of Assets and Liabilities | 9/30/17 (unaudited) ASSETS: Investment in securities of unaffiliated issuers, at value (cost $303,628,184) $ 308,164,782 Investment in securities of affiliated issuers, at value (cost $9,100,000) 8,490,271 Cash 726,244 Foreign currency, at value (cost $1,777) 63,633 Swap collateral 3,411,992 Futures collateral 237,000 Receivables -- Investment securities sold 1,052,544 Fund shares sold 7,609,927 Interest 2,629,592 Dividends 16,312 Due from broker for futures contracts 171,003 Variation margin on centrally cleared credit default swap contracts 109,620 Swap contracts, at value (net premiums paid $5,220,650) 5,880,869 Other assets 36,976 -------------------------------------------------------------------------------------------------------- Total assets $ 338,600,765 ======================================================================================================== LIABILITIES: Payables -- Investment securities purchased $ 11,969,339 Fund shares repurchased 853,601 Distributions 174,435 Trustee fees 27 Net unrealized depreciation on open forward foreign currency contracts 25,577 Net unrealized depreciation on open futures contracts 224,299 Due to broker for swap contracts 6,012,530 Open put options written (net premiums received $(213,979)) 93,004 Variation margin on futures contracts 51,500 Due to affiliates 57,445 Accrued expenses 116,669 -------------------------------------------------------------------------------------------------------- Total liabilities $ 19,578,426 ======================================================================================================== NET ASSETS: Paid-in capital $ 364,832,626 Distributions in excess of net investment income (2,424,228) Accumulated net realized loss on investments (47,902,997) Net unrealized appreciation on investments 4,516,938 -------------------------------------------------------------------------------------------------------- Net assets $ 319,022,339 ======================================================================================================== NET ASSET VALUE PER SHARE: (No par value, unlimited number of shares authorized) Class A (based on $37,320,810/3,961,166 shares) $ 9.42 Class C (based on $38,297,643/4,079,217 shares) $ 9.39 Class Y (based on $243,403,886/25,740,622 shares) $ 9.46 MAXIMUM OFFERING PRICE: Class A ($9.42 (divided by) 95.5%) $ 9.86 ======================================================================================================== The accompanying notes are an integral part of these financial statements. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 43 Statement of Operations (unaudited) For the Six Months Ended 9/30/17 INVESTMENT INCOME: Interest from unaffiliated issuers $6,999,598 Dividends from unaffiliated issuers 90,000 ---------------------------------------------------------------------------------------------------- Total investment income $ 7,089,598 ---------------------------------------------------------------------------------------------------- EXPENSES: Management fees $ 934,330 Transfer agent fees Class A 13,685 Class C 14,224 Class Y 83,383 Distribution fees Class A 46,439 Class C 191,406 Shareholder communications expense 5,937 Administrative expense 48,904 Custodian fees 33,076 Registration fees 49,109 Professional fees 30,291 Printing expense 7,666 Fees and expenses of nonaffiliated Trustees 4,570 Miscellaneous 24,486 ---------------------------------------------------------------------------------------------------- Total expenses $ 1,487,506 Less fees waived and expenses reimbursed by the Adviser (17,987) ---------------------------------------------------------------------------------------------------- Net expenses $ 1,469,519 ---------------------------------------------------------------------------------------------------- Net investment income $ 5,620,079 ---------------------------------------------------------------------------------------------------- REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS: Net realized gain (loss) on: Investments from unaffiliated issuers $1,947,635 Investments from affiliated issuers -- Swap contracts 1,892,403 Written options 461,836 Futures contracts (726,368) Forward foreign currency contracts (207,991) Other assets and liabilities denominated in foreign currencies (327,880) $ 3,039,635 ---------------------------------------------------------------------------------------------------- Change in net unrealized appreciation (depreciation) on: Investments from unaffiliated issuers $ (882,657) Investments from affiliated issuers (635,206) Swap contracts 11,582 Written options (34,829) Futures contracts (141,555) Forward foreign currency contracts 69,485 Other assets and liabilities denominated in foreign currencies 57,721 $(1,555,459) ---------------------------------------------------------------------------------------------------- Net realized and unrealized gain (loss) on investments $ 1,484,176 ---------------------------------------------------------------------------------------------------- Net increase in net assets resulting from operations $ 7,104,255 ==================================================================================================== The accompanying notes are an integral part of these financial statements. 44 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 Statements of Changes in Net Assets ---------------------------------------------------------------------------------------------------- Six Months Ended 9/30/17 Year Ended (unaudited) 3/31/17 ---------------------------------------------------------------------------------------------------- FROM OPERATIONS: Net investment income (loss) $ 5,620,079 $ 13,122,886 Net realized gain (loss) on investments 3,039,635 3,470,701 Change in net unrealized appreciation (depreciation) on investments (1,555,459) 12,507,732 ---------------------------------------------------------------------------------------------------- Net increase in net assets resulting from operations $ 7,104,255 $ 29,101,319 ---------------------------------------------------------------------------------------------------- DISTRIBUTIONS TO SHAREOWNERS: Net investment income: Class A ($0.21 and $0.58 per share, respectively) $ (803,552) $ (2,480,006) Class C ($0.17 and $0.51 per share, respectively) (691,760) (2,238,521) Class Y ($0.22 and $0.61 per share, respectively) (4,918,207) (12,489,189) ---------------------------------------------------------------------------------------------------- Total distributions to shareowners $ (6,413,519) $ (17,207,716) ---------------------------------------------------------------------------------------------------- FROM FUND SHARE TRANSACTIONS: Net proceeds from sale of shares $ 80,316,912 $ 86,714,586 Reinvestment of distributions 5,400,422 13,886,223 Cost of shares repurchased (38,668,725) (136,464,160) ---------------------------------------------------------------------------------------------------- Net increase (decrease) in net assets resulting from Fund share transactions $ 47,048,609 $ (35,863,351) ---------------------------------------------------------------------------------------------------- Net increase (decrease) in net assets $ 47,739,345 $ (23,969,748) NET ASSETS: Beginning of period 271,282,994 295,252,742 ---------------------------------------------------------------------------------------------------- End of period $ 319,022,339 $ 271,282,994 ---------------------------------------------------------------------------------------------------- Distributions in excess of net investment income $ (2,424,228) $ (1,630,788) ==================================================================================================== The accompanying notes are an integral part of these financial statements. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 45 Statements of Changes in Net Assets (continued) ----------------------------------------------------------------------------------------------- Six Months Six Months Ended Ended 9/30/17 9/30/17 Year Ended Year Ended Shares Amount 3/31/17 3/31/17 (unaudited) (unaudited) Shares Amount ----------------------------------------------------------------------------------------------- Class A Shares sold 966,896 $ 9,150,494 1,214,069 $ 11,415,582 Reinvestment of distributions 79,759 754,916 248,351 2,309,664 Less shares repurchased (853,516) (8,077,140) (2,956,245) (27,483,023) ----------------------------------------------------------------------------------------------- Net increase (decrease) 193,139 $ 1,828,270 (1,493,825) $ (13,757,777) =============================================================================================== Class C Shares sold 497,444 $ 4,693,352 522,227 $ 4,883,417 Reinvestment of distributions 63,956 603,420 209,119 1,939,023 Less shares repurchased (490,337) (4,624,445) (1,654,198) (15,310,288) ----------------------------------------------------------------------------------------------- Net increase (decrease) 71,063 $ 672,327 (922,852) $ (8,487,848) =============================================================================================== Class Y Shares sold 7,001,601 $ 66,473,066 7,500,358 $ 70,415,587 Reinvestment of distributions 425,288 4,042,086 1,031,639 9,637,536 Less shares repurchased (2,736,779) (25,967,140) (10,048,147) (93,670,849) ----------------------------------------------------------------------------------------------- Net increase (decrease) 4,690,110 $ 44,548,012 (1,516,150) $ (13,617,726) =============================================================================================== The accompanying notes are an integral part of these financial statements. 46 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 Financial Highlights ----------------------------------------------------------------------------------------------------------------------------------- Six Months Ended Year Year Year Year Year 9/30/17 Ended Ended Ended Ended Ended (unaudited) 3/30/17 3/30/16 3/30/15 3/30/14 3/30/13 ----------------------------------------------------------------------------------------------------------------------------------- Class A Net asset value, beginning of period $ 9.39 $ 8.99 $ 9.54 $ 9.94 $ 10.04 $ 9.63 ----------------------------------------------------------------------------------------------------------------------------------- Increase (decrease) from investment operations: Net investment income (loss) $ 0.18(a) $ 0.44(a) $ 0.42(a) $ 0.40 $ 0.41 $ 0.51 Net realized and unrealized gain (loss) on investments 0.06 0.54 (0.58) (0.47) (0.12) 0.45 ----------------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) from investment operations $ 0.24 $ 0.98 $ (0.16) $ (0.07) $ 0.29 $ 0.96 ----------------------------------------------------------------------------------------------------------------------------------- Distribution to shareowners: Net investment income $ (0.21) $ (0.58) $ (0.39) $ (0.33) $ (0.37) $ (0.55) Net realized gain -- -- -- -- (0.02) -- ----------------------------------------------------------------------------------------------------------------------------------- Total distributions $ (0.21) $ (0.58) $ (0.39) $ (0.33) $ (0.39) $ (0.55) ----------------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) in net asset value $ 0.03 $ 0.40 $ (0.55) $ (0.40) $ (0.09) $ 0.41 ----------------------------------------------------------------------------------------------------------------------------------- Net asset value, end of period $ 9.42 $ 9.39 $ 8.99 $ 9.54 $ 9.94 $ 10.04 =================================================================================================================================== Total return* 2.51% 11.13% (1.62)% (0.71)% 2.95% 10.24% Ratio of net expenses to average net assets 1.12%** 1.18% 1.19% 1.14% 1.19% 1.20% Ratio of net investment income (loss) to average net assets 3.79%** 4.71% 4.52% 3.76% 3.89% 5.05% Portfolio turnover rate 68%** 114% 56% 81% 95% 30% Net assets, end of period (in thousands) $37,321 $35,375 $47,311 $92,376 $161,097 $47,233 Ratios with no waiver of fees and assumption of expenses by the Adviser and no reduction for fees paid indirectly: Total expenses to average net assets 1.12%** 1.19% 1.19% 1.14% 1.19% 1.48% Net investment income (loss) to average net assets 3.79%** 4.70% 4.52% 3.76% 3.89% 4.77% =================================================================================================================================== * Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions, the complete redemption of the investment at net asset value at the end of each period and no sales charges. Total return would be reduced if sales charges were taken into account. ** Annualized. (a) The per-share data presented above is based on the average shares outstanding for the period presented. The accompanying notes are an integral part of these financial statements. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 47 Financial Highlights (continued) ----------------------------------------------------------------------------------------------------------------------------------- Six Months Ended Year Year Year Year Year 9/30/17 Ended Ended Ended Ended Ended (unaudited) 3/30/17 3/30/16 3/30/15 3/30/14 3/30/13 ----------------------------------------------------------------------------------------------------------------------------------- Class C Net asset value, beginning of period $ 9.36 $ 8.97 $ 9.51 $ 9.92 $ 10.02 $ 9.61 ----------------------------------------------------------------------------------------------------------------------------------- Increase (decrease) from investment operations: Net investment income (loss) $ 0.14(a) $ 0.36(a) $ 0.36(a) $ 0.31 $ 0.34 $ 0.44 Net realized and unrealized gain (loss) on investments 0.06 0.54 (0.58) (0.46) (0.13) 0.45 ----------------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) from investment operations $ 0.20 $ 0.90 $ (0.22) $ (0.15) $ 0.21 $ 0.89 ----------------------------------------------------------------------------------------------------------------------------------- Distribution to shareowners: Net investment income $ (0.17) $ (0.51) $ (0.32) $ (0.26) $ (0.29) $ (0.48) Net realized gain -- -- -- -- (0.02) -- ----------------------------------------------------------------------------------------------------------------------------------- Total distributions $ (0.17) $ (0.51) $ (0.32) $ (0.26) $ (0.31) $ (0.48) ----------------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) in net asset value $ 0.03 $ 0.39 $ (0.54) $ (0.41) $ (0.10) $ 0.41 ----------------------------------------------------------------------------------------------------------------------------------- Net asset value, end of period $ 9.39 $ 9.36 $ 8.97 $ 9.51 $ 9.92 $ 10.02 =================================================================================================================================== Total return* 2.15% 10.18% (2.25)% (1.58)% 2.19% 9.44% Ratio of net expenses to average net assets 1.87%** 1.94% 1.95% 1.90% 1.93% 1.95% Ratio of net investment income (loss) to average net assets 3.05%** 3.94% 3.86% 3.04% 3.18% 4.29% Portfolio turnover rate 68%** 114% 56% 81% 95% 30% Net assets, end of period (in thousands) $38,298 $37,510 $44,207 $70,793 $91,491 $28,796 Ratios with no waiver of fees and assumption of expenses by the Adviser and no reduction for fees paid indirectly: Total expenses to average net assets 1.87%** 1.95% 1.95% 1.90% 1.93% 2.23% Net investment income (loss) to average net assets 3.05%** 3.93% 3.86% 3.04% 3.18% 4.01% =================================================================================================================================== * Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions, the complete redemption of the investment at net asset value at the end of each period and no sales charges. Total return would be reduced if sales charges were taken into account. ** Annualized. (a) The per-share data presented above is based on the average shares outstanding for the period presented. The accompanying notes are an integral part of these financial statements. 48 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 ----------------------------------------------------------------------------------------------------------------------------------- Six Months Ended Year Year Year Year Year 9/30/17 Ended Ended Ended Ended Ended (unaudited) 3/30/17 3/30/16 3/30/15 3/30/14 3/30/13 ----------------------------------------------------------------------------------------------------------------------------------- Class Y Net asset value, beginning of period $ 9.42 $ 9.03 $ 9.58 $ 9.98 $ 10.08 $ 9.66 ----------------------------------------------------------------------------------------------------------------------------------- Increase (decrease) from investment operations: Net investment income (loss) $ 0.19(a) $ 0.47(a) $ 0.46(a) $ 0.41 $ 0.44 $ 0.55 Net realized and unrealized gain (loss) on investments 0.07 0.53 (0.58) (0.45) (0.12) 0.45 ----------------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) from investment operations $ 0.26 $ 1.00 $ (0.12) $ (0.04) $ 0.32 $ 1.00 ----------------------------------------------------------------------------------------------------------------------------------- Distribution to shareowners: Net investment income $ (0.22) $ (0.61) $ (0.43) $ (0.36) $ (0.40) $ (0.58) Net realized gain -- -- -- -- (0.02) -- ----------------------------------------------------------------------------------------------------------------------------------- Total distributions $ (0.22) $ (0.61) $ (0.43) $ (0.36) $ (0.42) $ (0.58) ----------------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) in net asset value $ 0.04 $ 0.39 $ (0.55) $ (0.40) $ (0.10) $ 0.42 ----------------------------------------------------------------------------------------------------------------------------------- Net asset value, end of period $ 9.46 $ 9.42 $ 9.03 $ 9.58 $ 9.98 $ 10.08 =================================================================================================================================== Total return* 2.77% 11.35% (1.26)% (0.43)% 3.24% 10.69% Ratio of net expenses to average net assets 0.85%** 0.85% 0.85% 0.85% 0.85% 0.85% Ratio of net investment income (loss) to average net assets 4.07%** 5.01% 4.90% 4.10% 4.24% 5.52% Portfolio turnover rate 68%** 114% 56% 81% 95% 30% Net assets, end of period (in thousands) $243,404 $198,398 $203,736 $397,203 $395,245 $131,013 Ratios with no waiver of fees and assumption of expenses by the Adviser and no reduction for fees paid indirectly: Total expenses to average net assets 0.87%** 0.96% 0.96% 0.93% 0.97% 1.21% Net investment income (loss) to average net assets 4.05%** 4.90% 4.79% 4.02% 4.12% 5.16% =================================================================================================================================== * Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions and the complete redemption of the investment at net asset value at the end of each period. ** Annualized. (a) The per-share data presented above is based on the average shares outstanding for the period presented. The accompanying notes are an integral part of these financial statements. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 49 Notes to Financial Statements |9/30/17 (unaudited) 1. Organization and Significant Accounting Policies Pioneer Dynamic Credit Fund (the Fund) is one of three portfolios comprising Pioneer Series Trust X, a Delaware statutory trust. The Fund is registered under the Investment Company Act of 1940 as a diversified, open-end management investment company. The investment objective of the Fund is to seek a high level of current income. Capital appreciation is a secondary objective. The Fund offers three classes of shares designated as Class A, Class C and Class Y shares. Each class of shares represents an interest in the same portfolio of investments of the Fund and has identical rights (based on relative net asset values) to assets and liquidation proceeds. Share classes can bear different rates of class-specific fees and expenses, such as transfer agent and distribution fees. Differences in class-specific fees and expenses will result in differences in net investment income and, therefore, the payment of different dividends from net investment income earned by each class. The Amended and Restated Declaration of Trust of the Fund gives the Board of Trustees the flexibility to specify either per-share voting or dollar-weighted voting when submitting matters for shareholder approval. Under per-share voting, each share of a class of the Fund is entitled to one vote. Under dollar-weighted voting, a shareholder's voting power is determined not by the number of shares owned, but by the dollar value of the shares on the record date. Each share class has exclusive voting rights with respect to matters affecting only that class, including with respect to the distribution plan for that class. There is no distribution plan for Class Y shares. On July 3, 2017, Amundi acquired Pioneer Investments, a group of asset management companies located throughout the world. Amundi, one of the world's largest asset managers, is headquartered in Paris, France. As a result of the transaction, Pioneer Investment Management, Inc., the Funds' investment adviser, became an indirect wholly owned subsidiary of Amundi and Amundi's wholly owned subsidiary, Amundi USA, Inc. Prior to July 3, 2017, Pioneer Investments was owned by Pioneer Global Asset Management S.p.A., a wholly owned subsidiary of UniCredit S.p.A. In connection with the transaction, the names of the Funds' investment adviser and principal underwriter changed. Effective July 3, 2017, the name of Pioneer Investment Management, Inc. changed to Amundi Pioneer Asset Management, Inc. (the Adviser) and the name of Pioneer Funds Distributor, Inc. changed to Amundi Pioneer Distributor, Inc. (the Distributor). 50 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 In October 2016, the Securities and Exchange Commission (SEC) released its Final Rule on Investment Company Reporting Modernization. In addition to introducing two new regulatory reporting forms (Form N-PORT and Form N-CEN), the Final Rule amends Regulation S-X, which impacts financial statement presentation, particularly related to the presentation of derivative investments. The Fund's financial statements were prepared in compliance with the amendments to Regulation S-X. The Fund's financial statements have been prepared in conformity with U.S. generally accepted accounting principles (U.S. GAAP) that require the management of the Fund to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of income, expenses and gains and losses on investments during the reporting period. Actual results could differ from those estimates. The Fund is an investment company and follows investment company accounting and reporting guidance under U.S. GAAP. The following is a summary of significant accounting policies followed by the Fund in the preparation of its financial statements: A. Security Valuation The net asset value of the Fund is computed once daily, on each day the New York Stock Exchange (NYSE) is open, as of the close of regular trading on the NYSE. Fixed-income securities are valued by using prices supplied by independent pricing services, which consider such factors as market prices, market events, quotations from one or more brokers, Treasury spreads, yields, maturities and ratings, or may use a pricing matrix or other fair value methods or techniques to provide an estimated value of the security or instrument. A pricing matrix is a means of valuing a debt security on the basis of current market prices for other debt securities, historical trading patterns in the market for fixed-income securities and/or other factors. Non-U.S. debt securities that are listed on an exchange will be valued at the bid price obtained from an independent third party pricing service. When independent third party pricing services are unable to supply prices, or when prices or market quotations are considered to be unreliable, the value of that security may be determined using quotations from one or more broker-dealers. Loan interests are valued in accordance with guidelines established by the Board of Trustees at the mean between the last available bid and asked prices from one or more brokers or dealers as obtained from Loan Pricing Corporation, an independent third party pricing service. If price information is not available from Loan Pricing Corporation, or if the price information is deemed to be unreliable, price information will be obtained from an Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 51 alternative loan interest pricing service. If no reliable price quotes are available from either the primary or alternative pricing service, broker quotes will be solicited. Event-linked bonds or catastrophe bonds are valued at the bid price obtained from an independent third party pricing service. Other insurance linked securities (including sidecars, collateralized reinsurance and industry loss warranties) may be valued at the bid price obtained from an independent pricing service, or through a third party using a pricing matrix, insurance industry valuation models, or other fair value methods or techniques to provide an estimated value of the instrument. The value of foreign securities is translated into U.S. dollars based on foreign currency exchange rate quotations supplied by a third party pricing source. Trading in non-U.S. equity securities is substantially completed each day at various times prior to the close of the NYSE. The values of such securities used in computing the net asset value of the Fund's shares are determined as of such times. The Fund may use a fair value model developed by an independent pricing service to value non-U.S. equity securities. Swap contracts, including interest rate swaps, caps and floors (other than centrally cleared swap contracts) are valued at the dealer quotations obtained from reputable International Swap Dealer Association members. Centrally cleared swaps are valued at the daily settlement price provided by the central clearing counterparty. Futures contracts are generally valued at the closing settlement price established by the exchange on which they are traded. Option contracts are generally valued at the mean between the last bid and ask prices on the principal exchange where they are traded. Over-the-counter ("OTC") options and options on swaps ("swaptions") are valued using prices supplied by independent pricing services, which consider such factors as market prices, market events, quotations from one or more brokers, Treasury spreads, yields, maturities and ratings, or may use a pricing matrix or other fair value methods or techniques to provide an estimated value of the security or instrument. Forward foreign currency exchange contracts are valued daily using the foreign exchange rate or, for longer term forward contract positions, the spot currency rate and the forward points on a daily basis, in each case provided by a third party pricing service. Contracts whose forward settlement date falls between two quoted days are valued by interpolation. Shares of open-end registered investment companies (including money market mutual funds) are valued at such funds' net asset value. Repurchase agreements are valued at par. Cash may include overnight time deposits at approved financial institutions. 52 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 Shares of closed-end interval funds that offer their shares at net asset value are valued at such funds' net asset value. Securities or loan interests for which independent pricing services or broker-dealers are unable to supply prices or for which market prices and/or quotations are not readily available or are considered to be unreliable are valued by a fair valuation team comprised of certain personnel of the Adviser pursuant to procedures adopted by the Fund's Board of Trustees. The Adviser's fair valuation team uses fair value methods approved by the Valuation Committee of the Board of Trustees. The Adviser's fair valuation team is responsible for monitoring developments that may impact fair valued securities and for discussing and assessing fair values on an ongoing basis, and at least quarterly, with the Valuation Committee of the Board of Trustees. Inputs used when applying fair value methods to value a security may include credit ratings, the financial condition of the company, current market conditions and comparable securities. The Fund may use fair value methods if it is determined that a significant event has occurred after the close of the exchange or market on which the security trades and prior to the determination of the Fund's net asset value. Examples of a significant event might include political or economic news, corporate restructurings, natural disasters, terrorist activity or trading halts. Thus, the valuation of the Fund's securities may differ significantly from exchange prices and such differences could be material. At September 30, 2017, three securities were valued using fair value methods (in addition to securities valued using prices supplied by independent pricing services, broker-dealers or using a third party insurance industry pricing model) representing 0.4% of net assets. B. Investment Income and Transactions Principal amounts of mortgage-backed securities are adjusted for monthly paydowns. Premiums and discounts related to certain mortgage-backed securities are amortized or accreted in proportion to the monthly paydowns. All discounts/premiums on purchase prices of debt securities are accreted/amortized for financial reporting purposes over the life of the respective securities, and such accretion/amortization is included in interest income. Interest income, including interest on income bearing cash accounts, is recorded on the accrual basis, net of unrecoverable foreign taxes withheld at the applicable country rates and net of income accrued on defaulted securities. Interest and dividend income payable by delivery of additional shares is reclassified as PIK (payment-in-kind) income upon receipt and is included in interest and dividend income, respectively. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 53 Security transactions are recorded as of trade date. Gains and losses on sales of investments are calculated on the identified cost method for both financial reporting and federal income tax purposes. C. Foreign Currency Translation The books and records of the Fund are maintained in U.S. dollars. Amounts denominated in foreign currencies are translated into U.S. dollars using current exchange rates. Net realized gains and losses on foreign currency transactions, if any, represent, among other things, the net realized gains and losses on foreign currency contracts, disposition of foreign currencies and the difference between the amount of income accrued and the U.S. dollars actually received. Further, the effects of changes in foreign currency exchange rates on investments are not segregated in the statement of operations from the effects of changes in the market price of those securities but are included with the net realized and unrealized appreciation or depreciation on investments. D. Forward Foreign Currency Contracts The Fund may enter into forward foreign currency contracts (contracts) for the purchase or sale of a specific foreign currency at a fixed price on a future date. All contracts are marked to market daily at the applicable exchange rates, and any resulting unrealized appreciation or depreciation are recorded in the Fund's financial statements. The Fund records realized gains and losses at the time a contract is offset by entry into a closing transaction or extinguished by delivery of the currency. Risks may arise upon entering into these contracts from the potential inability of counterparties to meet the terms of the contract and from unanticipated movements in the value of foreign currencies relative to the U.S. dollar. At September 30, 2017, the Fund had entered into various forward foreign currency contracts that obligate the Fund to deliver or take delivery of currencies at specified future maturity dates. Alternatively, prior to the settlement date of a forward foreign currency contract, the Fund may close out such contract by entering into an offsetting contract. The average value of contracts open during the six months ended September 30, 2017 was $(2,300,423). Forward foreign currency contracts outstanding at September 30, 2017 are listed in the Schedule of Investments. E. Federal Income Taxes It is the Fund's policy to comply with the requirements of the Internal Revenue Code applicable to regulated investment companies and to distribute all of its net taxable income and net realized capital gains, if any, to its shareowners. Therefore, no provision for federal income taxes is required. 54 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 As of March 31, 2017, the Fund had not accrued any interest or penalties with respect to uncertain tax positions, which, if applicable, would be recorded as an income tax expense in the Statement of Operations. Tax returns filed within the prior three years are subject to examination by Federal and State tax authorities. The amount and character of income and capital gain distributions to shareowners are determined in accordance with federal income tax rules, which may differ from U.S. GAAP. Distributions in excess of net investment income or net realized gains are temporary overdistributions for financial statement purposes resulting from differences in the recognition or classification of income or distributions for financial statement and tax purposes. Capital accounts within the financial statements are adjusted for permanent book/tax differences to reflect tax character, but are not adjusted for temporary differences. The tax character of distributions paid during the year ended March 31, 2017 was as follows: --------------------------------------------------------------------------------------- 2017 --------------------------------------------------------------------------------------- Distributions paid from: Ordinary income $ 17,207,716 --------------------------------------------------------------------------------------- Total $ 17,207,716 ======================================================================================= The following shows components of distributable earnings on a federal income tax basis at March 31, 2017. --------------------------------------------------------------------------------------- 2017 --------------------------------------------------------------------------------------- Undistributed ordinary income $ 41,933 Capital loss carryforward (51,082,659) Current year dividend payable (181,289) Unrealized appreciation 4,720,992 --------------------------------------------------------------------------------------- Total $(46,501,023) ======================================================================================= The difference between book-basis and tax-basis net unrealized appreciation is attributable to the tax adjustments relating to catastrophe bonds and credit default swaps, the mark-to-market of forward currency, option, interest on defaulted bonds and futures contracts. F. Fund Shares The Fund records sales and repurchases of its shares as of trade date. The Distributor, earned $12,589 in underwriting commissions on the sale of Class A shares during the six months ended September 30, 2017. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 55 G. Class Allocations Income, common expenses, and realized and unrealized gains and losses are calculated at the Fund level and allocated daily to each class of shares based on its respective percentage of adjusted net assets at the beginning of the day. Distribution fees are calculated based on the average daily net asset value attributable to Class A and Class C shares of the Fund, respectively (see Note 4). Class Y shares do not pay distribution fees. All expenses and fees paid to the Fund's transfer agent, for its services are allocated among the classes of shares based on the number of accounts in each class and the ratable allocation of related out-of-pocket expenses (see Note 3). The Fund declares as daily dividends substantially all of its net investment income. All dividends are paid on a monthly basis. Short-term capital gain distributions, if any, may be declared with the daily dividends. Distributions to shareowners are recorded as of the ex-dividend date. Distributions paid by the Fund with respect to each class of shares are calculated in the same manner and at the same time except that net investment income dividends to Class A, Class C and Class Y shares can reflect different transfer agent and distribution expense rates. H. Risks The value of securities held by the fund may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic, political or regulatory conditions, inflation, changes in interest rates, lack of liquidity in the bond markets or adverse investor sentiment. In the past several years, financial markets have experienced increased volatility, depressed valuations, decreased liquidity and heightened uncertainty. These conditions may continue, recur, worsen or spread. When interest rates rise, the prices of fixed-income securities in the Fund will generally fall. Conversely, when interest rates fall, the prices of fixed-income securities in the Fund will generally rise. Interest rates in the U.S. recently have been historically low, so the Fund faces a heightened risk that interest rates may rise. A general rise in interest rates may cause investors to move out of fixed income securities on a large scale, which could adversely affect the price and liquidity of fixed income securities and could also result in increased redemptions from the Fund. Investments in the Fund are subject to possible loss due to the financial failure of issuers of underlying securities and the issuers' inability to meet their debt obligations. Certain securities in which the Fund invests, including floating rate loans, once sold, may not settle for an extended period (for example, several weeks or even longer). The Fund will not receive its sale proceeds until that time, which may constrain the Fund's ability to meet its obligations (including obligations to redeeming 56 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 shareholders). The Fund's prospectus contains unaudited information regarding the Fund's principal risks. Please refer to that document when considering the Fund's principal risks. I. Insurance-Linked Securities (ILS) The Fund invests in event-linked bonds. Event-linked bonds are floating rate debt obligations for which the return of principal and the payment of interest are contingent on the non-occurrence of a pre-defined "trigger" event, such as a hurricane or an earthquake of a specific magnitude. The trigger event's magnitude may be based on losses to a company or industry, industry indexes or readings of scientific instruments, or may be based on specified actual losses. If a trigger event occurs, as defined within the terms of an event-linked bond, the Fund may lose a portion or all of its accrued interest and/or principal invested in such event-linked bond. The Fund is entitled to receive principal and interest payments so long as no trigger event occurs of the description and magnitude specified by the instrument. In addition to the specified trigger events, event-linked bonds may expose the Fund to other risks, including but not limited to issuer (credit) default, adverse regulatory or jurisdictional interpretations and adverse tax consequences. The Fund's investments in ILS may include special purpose vehicles ("SPVs") or similar instruments structured to comprise a portion of a reinsurer's catastrophe-oriented business, known as quota share instruments (sometimes referred to as reinsurance sidecars), or to provide reinsurance relating to specific risks to insurance or reinsurance companies through a collateralized instrument, known as collateralized reinsurance. Structured reinsurance investments also may include industry loss warranties ("ILWs"). A traditional ILW takes the form of a bilateral reinsurance contract, but there are also products that take the form of derivatives, collateralized structures, or exchange traded instruments. Structured reinsurance investments, including quota share instruments, collateralized reinsurance investments and ILWs, generally are subject to the same risks as event-linked bonds. In addition, where the instruments are based on the performance of underlying reinsurance contracts, the Fund has limited transparency into the individual underlying contracts and therefore must rely upon the risk assessment and sound underwriting practices of the issuer. Accordingly, it may be more difficult for PIM to fully evaluate the underlying risk profile of the Fund's structured reinsurance investments and therefore the Fund's assets are placed at greater risk of loss than if PIM had more complete information. Structured reinsurance instruments generally will be considered illiquid securities by the Fund. These securities may be difficult to purchase, sell or unwind. Illiquid securities also may be difficult to value. If the Fund is forced to sell an illiquid asset, the Fund may be forced to sell at a loss. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 57 J. Futures Contracts The Fund may enter into futures transactions in order to attempt to hedge against changes in interest rates, securities prices and currency exchange rates or to seek to increase total return. Futures contracts are types of derivatives. All futures contracts entered into by the Fund are traded on a futures exchange. Upon entering into a futures contract, the Fund is required to deposit with a broker an amount of cash or securities equal to the minimum "initial margin" requirements of the associated futures exchange. The amount of cash deposited with the broker as collateral at September 30, 2017 is recorded as "Futures Collateral" on the Statement of Assets and Liabilities. Subsequent payments for futures contracts ("variation margin") are paid or received by the Fund, depending on the daily fluctuation in the value of the contracts, and are recorded by the Fund as unrealized appreciation or depreciation. When the contract is closed, the Fund realizes a gain or loss equal to the difference between the opening and closing value of the contract as well as any fluctuation in foreign currency exchange rates where applicable. Futures contracts are subject to market risk, interest rate risk and currency exchange rate risk. Changes in value of the contracts may not directly correlate to the changes in value of the underlying securities. The average value of contracts open during the six months ended September 30, 2017 was $6,697,589. Open futures contracts at September 30, 2017 are listed in the Schedule of Investments. K. Repurchase Agreements Repurchase agreements are arrangements under which the Fund purchases securities from a broker-dealer or a bank, called the counterparty, upon the agreement of the counterparty to repurchase the securities from the Fund at a later date, and at a specific price, which is typically higher than the purchase price paid by the Fund. The securities purchased serve as the Fund's collateral for the obligation of the counterparty to repurchase the securities. The value of the collateral, including accrued interest, is required to be equal to or in excess of the repurchase price. The collateral for all repurchase agreements is held in safekeeping in the customer-only account of the Fund's custodian or a subcustodian of the Fund. The Adviser is responsible for determining that the value of the collateral remains at least equal to the repurchase price. In the event of a default by the counterparty, the Fund is entitled to sell the securities, but the Fund may not be able to sell them for the price at which they were purchased, thus causing a loss to the Fund. Additionally, if the counterparty becomes insolvent, there is some risk that the Fund will not have a right to the securities, or the immediate right to sell the securities. Open repurchase agreements as of September 30, 2017 are listed at the end of the Fund's Schedule of Investments. 58 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 L. Credit Default Swap Agreements A credit default swap is a contract between a buyer of protection and a seller of protection against a pre-defined credit event on an underlying reference obligation, which may be a single security or a basket or index of securities. The Fund may sell or buy credit default swap contracts to seek to increase the Fund's income, or to attempt to hedge the risk of default on portfolio securities. A credit default swap index is used to hedge risk or take a position on a basket of credit entities or indices. As a seller of protection, the Fund would be required to pay the notional (or other agreed-upon) value of the referenced debt obligation to the counterparty in the event of a default by a U.S. or foreign corporate issuer of a debt obligation, which would likely result in a loss to the Fund. In return, the Fund would receive from the counterparty a periodic stream of payments during the term of the contract provided that no event of default occurred. The maximum exposure of loss to the seller would be the notional value of the credit default swaps outstanding. If no default occurs, the Fund would keep the stream of payments and would have no payment obligation. The Fund may also buy credit default swap contracts in order to hedge against the risk of default of debt securities, in which case the Fund would function as the counterparty referenced above. When the Fund enters into a credit default swap contract, the protection buyer makes an upfront or periodic payment to the protection seller in exchange for the right to receive a contingent payment. An upfront payment made by the Fund, as the protection buyer, is recorded as a component of unrealized appreciation (depreciation) on open swap contracts in the Statement of Assets and Liabilities. Periodic payments received or paid by the Fund are recorded as realized gains or losses in the Statement of Operations. Credit default swap contracts are marked-to-market daily using valuations supplied by independent sources and the change in value, if any, is recorded as unrealized appreciation or depreciation in the Statement of Assets and Liabilities. Payments received or made as a result of a credit event or upon termination of the contract are recognized, net of the appropriate amount of the upfront payment, as realized gains or losses in the Statement of Operations. Credit default swap contracts involving the sale of protection may involve greater risks than if the Fund had invested in the referenced debt instrument directly. Credit default swap contracts are subject to general market risk, liquidity risk, counterparty risk and credit risk. If the Fund is a protection buyer and no credit event occurs, it will lose its investment. If the Fund is a protection seller and a credit event occurs, the value of the referenced debt instrument received by the Fund, together with the periodic payments received, may be less than the amount the Fund pays to the protection buyer, resulting in a loss to the Fund. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 59 Certain swap contracts that are cleared through a central clearinghouse are referred to as centrally cleared swaps. All payments made or received by the Fund are pursuant to a centrally cleared swap contract with the central clearing party rather than the original counterparty. Upon entering into a centrally cleared swap contract, the Fund is required to make an initial margin deposit, either in cash or in securities. The daily change in value on open centrally cleared contracts is recorded as variation margin on centrally cleared swaps on the Statement of Assets and Liabilities. The amount of cash deposited with a broker as collateral at September 30, 2017 is recorded as "Swap Collateral" on the Statement of Assets and Liabilities. Open credit default swap contracts at September 30, 2017 are listed in the Schedule of Investments. The average value of swap contracts open during the six months ended September 30, 2017 was $4,580,399. M. Purchased Options The Fund may purchase put and call options to seek increase total return. Purchased call and put options entitle the Fund to buy and sell a specified number of shares or units of a particular security, currency or index at a specified price at a specific date or within a specific period of time. Upon the purchase of a call or put option, the premium paid by the Fund is included in the Statement of Assets and Liabilities as an investment. All premiums are marked-to-market daily, and any unrealized gains or losses are recorded in the Fund's financial statements. As the purchaser of an index option, the Fund has the right to receive a cash payment equal to any depreciation in the value of the index below the strike price of the option (in the case of a put) or equal to any appreciation in the value of the index over the strike price of the option (in the case of a call) as of the valuation date of the option. Premiums paid for purchased calls and put options which have expired are treated as realized losses on investments in the Statement of Operations. Upon the exercise or closing of a purchased put option, the premium is offset against the proceeds on the sale of the underlying security or financial instrument in order to determine the realized gain or loss on investments. Upon the exercise or closing of a purchased call option, the premium is added to the cost of the security or financial instrument. The risk associated with purchasing options is limited to the premium originally paid. The average value of purchased options open for the six months ended September 30, 2017 was $293,508. Purchased option contracts outstanding at period end are listed in the Schedule of Investments. 60 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 N. Option Writing The Fund may write put and covered call options to seek to increase total return. When an option is written, the Fund receives a premium and becomes obligated to purchase or sell the underlying security at a fixed price upon the exercise of the option. When the Fund writes an option, an amount equal to the premium received by the Fund is recorded as a liability and is subsequently adjusted to the current value of the option written. Premiums received from writing options that expire unexercised are treated by the Fund on the expiration date as realized gains from investments. The difference between the premium and the amount paid on effecting a closing purchase transaction, including brokerage commissions, is also treated as a realized gain or, if the premium is less than the amount paid for the closing purchase transaction, as a realized loss. If a call option is exercised, the premium is added to the proceeds from the sale of the underlying security in determining whether the Fund has realized a gain or loss. The Fund as writer of an option bears the market risk of an unfavorable change in the price of the security underlying the written option. The average value of written option contracts open during the six months ended September 30, 2017 was $(98,160). Written option contracts outstanding at September 30, 2017 are listed in the Schedule of Investments. The Fund held six written options that were open at September 30, 2017. If the options were exercised at September 30, 2017, the maximum amount the Fund would have been required to pay was $213,979. 2. Management Agreement The Adviser manages the Fund's portfolio. Management fees are calculated daily at the annual rate equal to 0.70% of the Fund's average daily net assets up to $1 billion and 0.65% on assets over $1 billion. For the six months ended September 30, 2017, the effective management fee (excluding waivers and/or assumption of expenses and acquired fund fees and expenses) was equivalent to 0.65% of the Fund's average daily net assets. The Adviser has contractually agreed to limit ordinary operating expenses (ordinary operating expenses means all fund expenses other than extraordinary expenses, such as litigation, taxes, brokerage commissions and acquired fund fees and expenses) of the Fund to the extent required to reduce Fund expenses to 1.20% and 0.85% of the average daily net assets attributable to Class A and Class Y shares. Fees waived and expenses reimbursed during the six months ended September 30, 2017 are reflected on the Statement of Operations. These expense limitations are in effect through August 1, 2019. There can be no assurance that the Adviser will extend the expense limitation agreement for a class of shares beyond the date referred to above. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 61 In addition, under the management and administration agreements, certain other services and costs, including accounting, regulatory reporting, and insurance premiums, are paid by the Fund as administrative reimbursements. Included in "Due to affiliates" reflected on the Statement of Assets and Liabilities is $47,009 in management fees, administrative costs and certain other reimbursements payable to the Adviser at September 30, 2017. 3. Transfer Agent Boston Financial Data Services, Inc. serves as the transfer agent to the Fund at negotiated rates. Transfer agent fees and payables shown on the Statement of Operations and the Statement of Assets and Liabilities, respectively, include sub-transfer agent expenses incurred through the Fund's omnibus relationship contracts. In addition, the Fund reimbursed the transfer agent for out-of-pocket expenses incurred by the transfer agent related to shareholder communications activities such as proxy and statement mailings and outgoing phone calls. For the six months ended September 30, 2017, such out-of-pocket expenses by class of shares were as follows: ------------------------------------------------------------------------------- Shareholder Communications: ------------------------------------------------------------------------------- Class A $1,655 Class C 2,201 Class Y 2,081 ------------------------------------------------------------------------------- Total $5,937 =============================================================================== 4. Distribution Plan The Fund has adopted a Distribution Plan pursuant to Rule 12b-1 of the Investment Company Act of 1940 with respect to its Class A and Class C shares. Pursuant to the Plan, the Fund pays the Distributor 0.25% of the average daily net assets attributable to Class A shares as compensation for personal services and/or account maintenance services or distribution services with regard to Class A shares. Pursuant to the Plan, the Fund also pays the Distributor 1.00% of the average daily net assets attributable to Class C shares. The fee for Class C shares consists of a 0.25% service fee and a 0.75% distribution fee paid as compensation for personal services and/or account maintenance services or distribution services with regard to Class C shares. Included in "Due to affiliates" reflected on the Statement of Assets and Liabilities is $10,436 in distribution fees payable to the Distributor at September 30, 2017. In addition, redemptions of each class of shares (except Class Y shares) may be subject to a contingent deferred sales charge (CDSC). A CDSC of 1.00% may be imposed on redemptions of certain net asset value purchases of Class A shares within 12 months of purchase. Redemptions of Class C shares within 62 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 12 months of purchase are subject to a CDSC of 1.00%, based on the lower of cost or market value of shares being redeemed. Shares purchased as part of an exchange remain subject to any CDSC that applied to the original purchase of those shares. There is no CDSC for Class Y shares. Proceeds from the CDSCs are paid to the Distributor. For the six months ended September 30, 2017, CDSCs in the amount of $2,965 were paid to the Distributor. 5. Assets and Liabilities Offsetting The Fund has entered into an International Swaps and Derivatives Association, Inc. Master Agreement ("ISDA Master Agreement") or similar agreement with substantially all its derivative counterparties. An ISDA Master Agreement is a bilateral agreement between the Fund and a counterparty that governs the trading of certain OTC derivatives and typically contains, among other things, close-out and set-off provisions which apply upon the occurrence of event of a default and/or termination event as defined under the relevant ISDA Master Agreement. The ISDA Master Agreement may also give a party the right to terminate all transactions traded under such agreement if, among other things, there is deterioration in the credit quality of the other party. Upon an event of default or a termination of the ISDA Master Agreement, the non-defaulting party has the right to close out all transactions under such agreement and to net amounts owed under each transaction to determine one net amount payable by one party to the other. The right to close out and net payments across all transactions under the ISDA Master Agreement could result in a reduction of the Fund's credit risk to its counterparty equal to any amounts payable by the Fund under the applicable transactions, if any. However, the Fund's right to setoff may be restricted or prohibited by the bankruptcy or insolvency laws of the particular jurisdiction to which each specific ISDA of each counterparty is subject. The collateral requirements for derivatives transactions under an ISDA Master Agreement are governed by a credit support annex to the ISDA Master Agreement. Collateral requirements are generally determined at the close of business each day and are typically based on changes in market values for each transaction under an ISDA Master Agreement and netted into one amount for such agreement. Generally, the amount of collateral due from or to a counterparty is subject to threshold (a "minimum transfer amount") before a transfer is required, which may vary by counterparty. Collateral pledged for the benefit of the Fund and/or counterparty is held in segregated accounts by the Fund's custodian and cannot be sold, re-pledged, assigned or otherwise used while pledged. Cash that has been segregated to cover the Fund's collateral obligations, if any, will be reported separately in the Statement of Assets and Liabilities as "Futures and Swap Collateral." Securities pledged by the Fund as collateral, if any, are identified as such in the Schedule of Investments. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 63 Financial instruments subject to an enforceable master netting agreement such as an ISDA Master Agreement have been offset on the Statement of Assets and Liabilities. The following charts show gross assets and liabilities of the Fund as of September 30, 2017. ------------------------------------------------------------------------------------------------------------ Derivative Assets Derivatives Non-Cash Cash Net Amount Subject to Master Available for Collateral Collateral of Derivative Counterparty Netting Agreement Offset Received (a) Received (a) Assets (b) ------------------------------------------------------------------------------------------------------------ Citibank NA New York NY $ 74,238 $ -- $-- $-- $ 74,238 Barclays Bank Plc -- -- -- -- -- Brown Brothers Harriman & Co. 1,700 -- -- -- 1,700 Goldman Sachs International 511,086 (40,589) -- -- 470,497 JP Morgan Chase Bank NA 17,717 (17,717) -- -- -- State Street Bank And Trust Co. 2,596 (2,596) -- -- -- ------------------------------------------------------------------------------------------------------------ Total $607,337 $(60,902) $-- $-- $ 546,435 ============================================================================================================ ------------------------------------------------------------------------------------------------------------ Derivative Liabilities Derivatives Non-Cash Cash Net Amount Subject to Master Available for Collateral Collateral of Derivative Counterparty Netting Agreement Offset Pledged (a) Pledged (a) Liabilities (c) ------------------------------------------------------------------------------------------------------------ Citibank NA New York NY $ -- $ -- $-- $ -- $ -- Barclays Bank Plc 44,596 -- -- (44,596) -- Brown Brothers Harriman & Co. -- -- -- -- -- Goldman Sachs International 40,589 (40,589) -- -- -- JP Morgan Chase Bank NA 210,441 (17,717) -- (192,724) -- State Street Bank And Trust Co. 84,300 (2,596) -- -- 81,704 ------------------------------------------------------------------------------------------------------------ Total $379,926 $(60,902) $-- $(237,320) $ 81,704 ============================================================================================================ (a) The amount presented here may be less than the total amount of collateral received/pledged as the net amount of derivative assets and liabilities cannot be less than $0. (b) Represents the net amount due from the counterparty in the event of default. (c) Represents the net amount payable to the counterparty in the event of default. 6. Additional Disclosures about Derivative Instruments and Hedging Activities: The Fund's use of derivatives may subject it to the following risks: Interest rate risk relates to the fluctuations in the value of interest-bearing securities due to changes in the prevailing levels of market interest rates. Credit risk relates to the ability of the issuer of a financial instrument to make further principal or interest payments on an obligation or commitment that it has to the Fund. 64 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 Foreign exchange rate risk relates to fluctuations in the value of an asset or liability due to changes in currency exchange rates. Equity risk relates to the fluctuations in the value of financial instruments as a result of changes in market prices (other than those arising from interest rate risk or foreign exchange risk), whether caused by factors specific to an individual investment, its issuer, or all factors affecting all instruments traded in a market or market segment. Commodity risk relates to the risk that the value of a commodity or commodity index will fluctuate based on increases or decreases in the commodities market and factors specific to a particular industry or commodity. The fair value of open derivative instruments (not considered to be hedging instruments for accounting disclosure purposes) by risk exposure at September 30, 2017 was as follows: ----------------------------------------------------------------------------------------- Foreign Statement of Assets Interest Credit Exchange Equity Commodity and Liabilities Rate Risk Risk Rate Risk Risk ----------------------------------------------------------------------------------------- Assets Swaps contracts, at value $-- $5,880,869 $-- $-- $-- ----------------------------------------------------------------------------------------- Total Value $-- $5,880,869 $-- $-- $-- ========================================================================================= ----------------------------------------------------------------------------------------- Foreign Statement of Assets Interest Credit Exchange Equity Commodity and Liabilities Rate Risk Risk Rate Risk Risk ----------------------------------------------------------------------------------------- Liabilities Net unrealized depreciation of forward foreign currency contracts $ -- $-- $25,577 $ -- $-- Unrealized depreciation on futures contracts 224,299 -- -- -- -- Written options -- -- -- 93,004 -- ----------------------------------------------------------------------------------------- Total Value $224,299 $-- $25,577 $93,004 $-- ========================================================================================= Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 65 The effect of derivative instruments (not considered to be hedging instruments for accounting disclosure purposes) on the Statement of Operations by risk exposure at September 30, 2017 was as follows: ----------------------------------------------------------------------------------------------------- Foreign Interest Credit Exchange Equity Commodity Statement of Operations Rate Risk Risk Rate Risk Risk Risk ----------------------------------------------------------------------------------------------------- Net realized gain (loss) on Swap contracts $ -- $1,892,403 $ -- $ -- $-- Futures contracts (726,368) -- -- -- -- Written options -- -- -- 461,836 -- Forward foreign currency contracts** -- -- (207,992) -- -- ----------------------------------------------------------------------------------------------------- Total Value $(726,368) $1,892,403 $(207,992) $ 461,836 $-- ===================================================================================================== Change in net unrealized appreciation (depreciation) on Swap contracts $ -- $ 11,582 $ -- $ -- $-- Futures contracts (141,555) -- -- -- -- Written options -- -- -- (34,829) -- Forward foreign currency contracts** -- -- 69,485 -- -- ----------------------------------------------------------------------------------------------------- Total Value $(141,555) $ 11,582 $ 69,485 $ (34,829) $-- ===================================================================================================== ** Included in the amount shown on the Statement of Operations as forward foreign currency contracts and other assets and liabilities denominated in foreign currencies. 7. Line of Credit Facility The Fund, along with certain other funds in the Pioneer Family of Funds (the Funds), participates in a committed, unsecured revolving line of credit facility. Borrowings are used solely for temporary or emergency purposes. The Fund may borrow up to the lesser of the amount available under the facility or the limits set for borrowing by the Fund's prospectus and the 1940 Act. The credit facility in which the Fund participated until February 9, 2016 was in the amount of $240 million. The credit facility in which the Fund participated until February 7, 2017, was in the amount of $220 million. Effective February 8, 2017, the Fund participates in a facility that is in the amount of $25 million. Under such facility, depending on the type of loan, interest on borrowings is payable at the London Interbank Offered Rate (LIBOR) plus 0.90% on an annualized basis, or the Alternate Base Rate, which is the greater of (a) the facility's administrative agent's daily announced prime rate on the borrowing date, (b) 2% plus the Federal Funds Rate on the borrowing date or (c) 2% plus the overnight Eurodollar rate on the borrowing date. The Funds pay an annual commitment fee to participate in a credit facility. The commitment fee is allocated among participating Funds based on an allocation schedule set forth in the credit agreement. For the six months ended September 30, 2017, the Fund had no borrowings under the credit facility. 66 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 8. Unfunded Loan Commitments The Fund may enter into unfunded loan commitments. Unfunded loan commitments may be partially or wholly unfunded. During the contractual period, the Fund is obligated to provide funding to the borrower upon demand. A fee is earned by the Fund on the unfunded commitment and is recorded as interest income in the Statement of Operations. As of September 30, 2017, the Fund had the following unfunded loan commitments outstanding: ---------------------------------------------------------------------------------------------------- Unrealized Appreciation/ Loan Shares Cost Value Depreciation ---------------------------------------------------------------------------------------------------- Beacon Roofing Supply Inc., Bridge Loan 695,000 $695,000 $695,000 $-- ---------------------------------------------------------------------------------------------------- Total $695,000 $695,000 $-- ==================================================================================================== 9. Shareholder Meeting Results At a special meeting held on June 13, 2017, shareholders of the Fund were asked to consider the proposals described below. A report of the total votes cast by the Fund's shareholders (or, with respect to Proposal 2, by shareholders of Pioneer Series Trust X, as noted below) follows: ------------------------------------------------------------------------------------------------------- For Against Abstain Broker Non-Votes ------------------------------------------------------------------------------------------------------- Proposal 1 - To approve 14,778,510.845 134,540.888 197,188.888 3,345,682.500 a New Management Agreement with the Adviser ------------------------------------------------------------------------------------------------- For Withhold ------------------------------------------------------------------------------------------------- Proposal 2 - To elect Trustees* ------------------------------------------------------------------------------------------------- David R. Bock 343,352,480.124 5,326,068.613 ------------------------------------------------------------------------------------------------- Benjamin M. Friedman 343,252,747.228 5,425,801.509 ------------------------------------------------------------------------------------------------- Margaret B.W. Graham 343,431,726.450 5,246,822.287 ------------------------------------------------------------------------------------------------- Lisa M. Jones 343,414,583.887 5,263,964.850 ------------------------------------------------------------------------------------------------- Lorraine H. Monchak 339,444,451.562 9,234,097.175 ------------------------------------------------------------------------------------------------- Thomas J. Perna 343,393,493.010 5,285,055.727 ------------------------------------------------------------------------------------------------- Marguerite A. Piret 343,442,072.938 5,236,475.799 ------------------------------------------------------------------------------------------------- Fred J. Ricciardi 343,367,033.730 5,311,515.007 ------------------------------------------------------------------------------------------------- Kenneth J. Taubes 343,361,588.526 5,316,960.211 ------------------------------------------------------------------------------------------------- * Proposal 2 was voted on and approved by all series of Pioneer Series Trust X. Results reported above reflect the combined votes of all series of the Trust. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 67 ADDITIONAL INFORMATION Change in Independent Registered Public Accounting Firm Prior to July 3, 2017, Pioneer Investment Management, Inc. (the "Adviser"), the Fund's investment adviser, was an indirect, wholly owned subsidiary of UniCredit S.p.A. ("UniCredit"). On that date, UniCredit completed the sale of its Pioneer Investments business, which includes the Adviser, to Amundi (the "Transaction"). As a result of the Transaction, the Adviser became an indirect, wholly-owned subsidiary of Amundi. Amundi is controlled by Credit Agricole S.A. Amundi is headquartered in Paris, France, and, as of September 30, 2016, had more than $1.1 trillion in assets under management worldwide. Deloitte & Touche LLP ("D&T"), the Fund's previous independent registered public accounting firm, informed the Audit Committee and the Board that it would no longer be independent with respect to the Fund upon the completion of the Transaction as a result of certain services being provided to Amundi and Credit Agricole, and, accordingly, that it intended to resign as the Fund's independent registered public accounting firm upon the completion of the Transaction. D&T's resignation was effective on July 3, 2017, when the Transaction was completed. During the periods as to which D&T has served as the Fund's independent registered public accounting firm, including the Fund's two most recent fiscal years preceding the fiscal year ended March 31, 2017, D&T's reports on the Fund's financial statements have not contained an adverse opinion or disclaimer of opinion and have not been qualified or modified as to uncertainty, audit scope or accounting principles. Further, there have been no disagreements with D&T on any matter of accounting principles or practices, financial statement disclosure, or auditing scope or procedure, which, if not resolved to the satisfaction of D&T, would have caused D&T to make reference to the subject matter of the disagreement in connection with its report on the financial statements. In addition, there have been no reportable events of the kind described in Item 304(a)(1)(v) of Regulation S-K under the Securities Exchange Act of 1934. Effective immediately following the completion of the Transaction on July 3, 2017, the Board, acting upon the recommendation of the Audit Committee, engaged a new independent registered public accounting firm, Ernst & Young LLP ("EY"), for the Fund's fiscal year ended March 31, 2018. 68 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 Prior to its engagement, EY had advised the Fund's Audit Committee that EY had identified the following matters, in each case relating to services rendered by other member firms of Ernst & Young Global Limited, all of which are located outside the United States, to UniCredit and certain of its subsidiaries during the period commencing July 1, 2016, that it determined to be inconsistent with the auditor independence rules set forth by the Securities and Exchange Commission ("SEC"): (a) project management support services to UniCredit in the Czech Republic, Germany, Italy, Serbia and Slovenia in relation to twenty-two projects, that were determined to be inconsistent with Rule 2-01(c)(4)(vi) of Regulation S-X (management functions); (b) two engagements for UniCredit in Italy where fees were contingent/success based and that were determined to be inconsistent with Rule 2-01(c)(5) of Regulation S-X (contingent fees); (c) four engagements where legal and expert services were provided to UniCredit in the Czech Republic and Germany, and twenty engagements where the legal advisory services were provided to UniCredit in Austria, Czech Republic, Italy and Poland, that were determined to be inconsistent with Rule 2-01(c)(4)(ix) and (x) of Regulation S-X (legal and expert services); and (d) two engagements for UniCredit in Italy involving assistance in the sale of certain assets, that were determined to be inconsistent with Rule 2-01(c)(4)(viii) of Regulation S-X (broker-dealer, investment advisor or investment banking services). None of the foregoing services involved the Fund, any of the other funds in the Pioneer Family of Funds or any other Pioneer entity sold by UniCredit in the Transaction. EY advised the Audit Committee that it had considered the matters described above and had concluded that such matters would not impair EY's ability to exercise objective and impartial judgment in connection with the audits of the financial statements of the Fund under the SEC and Public Company Accounting Oversight Board independence rules, and that a reasonable investor with knowledge of all relevant facts and circumstances would reach the same conclusion. Management and the Audit Committee considered these matters and discussed the matters with EY and, based upon EY's description of the matters and statements made by EY, Management and the Audit Committee believe that EY will be capable of exercising objective and impartial judgment in connection with the audits of the financial statements of the Fund, and Management further believes that a reasonable investor with knowledge of all relevant facts and circumstances would reach the same conclusion. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 69 Trustees, Officers and Service Providers Trustees Officers Thomas J. Perna, Chairman Lisa M. Jones, President and Chief David R. Bock Executive Officer Benjamin M. Friedman Mark E. Bradley, Treasurer and Margaret B.W. Graham Chief Financial Officer Lisa M. Jones Christopher J. Kelley, Secretary and Lorraine H. Monchak Chief Legal Officer Marguerite A. Piret Fred J. Ricciardi Kenneth J. Taubes Investment Adviser and Administrator Amundi Pioneer Asset Management, Inc. Custodian and Sub-Administrator Brown Brothers Harriman & Co. Principal Underwriter Amundi Pioneer Distributor, Inc. Legal Counsel Morgan, Lewis & Bockius LLP Transfer Agent Boston Financial Data Services, Inc. Proxy Voting Policies and Procedures of the Fund are available without charge, upon request, by calling our toll free number (1-800-225-6292). Information regarding how the Fund voted proxies relating to portfolio securities during the most recent 12-month period ended June 30 is publicly available to shareowners at www.amundipioneer.com. This information is also available on the Securities and Exchange Commission's web site at www.sec.gov. 70 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 This page is for your notes. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 71 This page is for your notes. 72 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 This page is for your notes. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 73 This page is for your notes. 74 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 This page is for your notes. Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 75 This page is for your notes. 76 Pioneer Dynamic Credit Fund | Semiannual Report | 9/30/17 How to Contact Amundi Pioneer We are pleased to offer a variety of convenient ways for you to contact us for assistance or information. Call us for: -------------------------------------------------------------------------------- Account Information, including existing accounts, new accounts, prospectuses, applications and service forms 1-800-225-6292 FactFone(SM) for automated fund yields, prices, account information and transactions 1-800-225-4321 Retirement plans information 1-800-622-0176 Write to us: -------------------------------------------------------------------------------- Amundi Pioneer P.O. Box 55014 Boston, Massachusetts 02205-5014 Our toll-free fax 1-800-225-4240 Our internet e-mail address ask.amundipioneer@amundipioneer.com (for general questions about Amundi Pioneer only) Visit our web site: www.amundipioneer.com This report must be preceded or accompanied by a prospectus. The Fund files a complete schedule of investments with the Securities and Exchange Commission for the first and third quarters for each fiscal year on Form N-Q. Shareholders may view the filed Form N-Q by visiting the Commission's web site at www.sec.gov. The filed form may also be viewed and copied at the Commission's Public Reference Room in Washington, DC. Information regarding the operations of the Public Reference Room may be obtained by calling 1-800-SEC-0330. [LOGO] Amundi Pioneer ============== ASSET MANAGEMENT Amundi Pioneer Asset Management, Inc. 60 State Street Boston, MA 02109 www.amundipioneer.com Securities offered through Amundi Pioneer Distributor, Inc. 60 State Street, Boston, MA 02109 Underwriter of Pioneer Mutual Funds, Member SIPC (C) 2017 Amundi Pioneer Asset Management 25266-06-1117 Pioneer Fundamental Growth Fund -------------------------------------------------------------------------------- Semiannual Report | September 30, 2017 -------------------------------------------------------------------------------- Ticker Symbols: Class A PIGFX Class C FUNCX Class K PFGKX Class R PFGRX Class Y FUNYX [LOGO] Amundi Pioneer ============== ASSET MANAGEMENT visit us: www.amundipioneer.com Table of Contents President's Letter 2 Portfolio Management Discussion 4 Portfolio Summary 10 Prices and Distributions 11 Performance Update 12 Comparing Ongoing Fund Expenses 17 Schedule of Investments 19 Financial Statements 24 Notes to Financial Statements 33 Additional Information 42 Trustees, Officers and Service Providers 44 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 1 President's Letter Robust, synchronized global economic growth and rising corporate profits have continued to drive strong performance in both the credit and equity markets for most of 2017. U.S. stocks, as measured by the Standard & Poor's 500 Index, have returned 14.23% year-to-date through September 30, 2017. Fixed-income markets, while not generating the same dazzling returns as equities, have held their own, led by high-yield securities, which produced a year-to-date return of 7.05% in the U.S., as measured by the Bank of America Merrill Lynch U.S. High Yield Index. Meanwhile, the Bloomberg Barclays U.S. Aggregate Bond Index has returned 3.14% since the start of the calendar year. Continued strong employment numbers and higher consumer confidence, together with solid global economic growth and a depreciating U.S. dollar contributed to better-than-expected U.S. gross domestic product (GDP) growth of 3.1% in the second quarter. Outside the U.S., economic growth in the second quarter also surprised to the upside across the Euro zone, China, and Japan. Meanwhile, despite higher oil and commodities prices, inflation continued to be moderate, both in the U.S. and globally, enabling major non-U.S. central banks to maintain their easy monetary policies. As expected, however, the U.S. Federal Reserve System (the Fed) recently announced that it would commence tapering its balance sheet this October. The Fed also appears primed to raise interest rates one more time before the end of this year, which would be the fourth rate increase since December of 2016. As we move into the final months of 2017, we believe the U.S. economy will experience modest growth in the short term, depending on the mix of economic policies enacted as the country moves away from monetary stimulus (driven by the Fed) and toward fiscal stimulus (potentially including tax reform) as well as lighter regulatory burdens. Meanwhile, corporate earnings remain solid and we think they will improve even further, despite some pressure from wage increases. In addition, as the economy continues to grow and we begin to see a modest upturn in inflation, we believe the Fed will continue to raise interest rates. While economic and market conditions appear solid, there are always risks to consider that could dampen the outlook. Geopolitical concerns, such as increased tensions with North Korea, and continued political gridlock in Washington are just some of the risks that could lead to increased market volatility. 2 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 It is for those reasons that we at Amundi Pioneer continue to believe that investors can benefit from the experience and tenure of our investment teams who make active and informed decisions across our funds. As always, and particularly during times of market uncertainty, we encourage you to work with your financial advisor to develop an overall investment plan that addresses both your short- and long-term goals, and to implement such a plan in a disciplined manner. We greatly appreciate the trust you have placed in us and look forward to continuing to serve you in the future. Sincerely, /s/ Lisa M. Jones Lisa M. Jones Head of the Americas, President and CEO of U.S. Amundi Pioneer Asset Management USA, Inc. September 30, 2017 Any information in this shareowner report regarding market or economic trends or the factors influencing the Fund's historical or future performance are statements of opinion as of the date of this report. Past performance is no guarantee of future results. Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 3 Portfolio Management Discussion | 9/30/17 The U.S. stock market generated solid results over the six-month period ended September 30, 2017, sustaining a persistent rally that began in late 2016. In the following interview, Andrew Acheson and Paul Cloonan discuss the factors that affected the performance of Pioneer Fundamental Growth Fund during the period. Mr. Acheson and Mr. Cloonan, both senior vice presidents and portfolio managers at Amundi Pioneer Asset Management, Inc. ("Amundi Pioneer"), are responsible for the day-to-day management of the Fund. Q How did the Fund perform during the six-month period ended September 30, 2017? A Pioneer Fundamental Growth Fund's Class A shares returned 8.61% at net asset value during the six-month period ended September 30, 2017, while the Fund's benchmark, the Russell 1000 Growth Index (the Russell Index), returned 10.84%. During the same period, the average return of the 700 mutual funds in Lipper's Large Cap Growth Funds category was 11.28%, and the average return of the 1,450 mutual funds in Morningstar's Large Growth Funds category was 10.44%. Q How would you describe the investment environment for domestic equities during the six-month period ended September 30, 2017? A Domestic equities kept gaining ground over the period in a rally characterized by little market volatility and few interruptions, even in the face of some global geopolitical and domestic political concerns. Propelling the market's upward momentum, in part, were strong corporate earnings reports for the first quarter of 2017 as well as continued strength in the energy sector, which had struggled early in the year. Another noteworthy factor sustaining the rally was the expectation that President Trump's new Republican administration, combined with Republican control of Congress, would lead to an era of deregulation in the markets, a development considered particularly important to the financials sector and the small business community. Hopes for a tax reform package featuring reductions in corporate and personal tax rates also drove the market's optimism. Over the six months, the U.S. Federal Reserve (the Fed) appeared to slow its pace of interest-rate hikes. After raising the influential federal funds rate twice in the previous six-month period, the Fed hiked rates just once in June 2017, and seemed to back away from its earlier stance of multiple, additional rate increases over the balance of the calendar year, as inflationary pressures remained relatively benign. Near the end of the period, however, the Fed did indicate that it would begin reducing its 4 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 balance sheet by shedding some of the securities it purchased during its multiple quantitative-easing programs between 2008 and 2014. In addition, a December 2017 federal funds rate hike, which would be the fourth increase dating back to December 2016, seemed likely. During the six-month period, there was a sustained rally in the prices of large-cap growth stocks, in particular, led by high-valuation equities and more cyclical industries and sectors, including semiconductors, technology, and financials. Health care stocks, after lagging behind market trends in the previous 18 months, staged a strong rebound as well. In contrast, the consumer staples sector - often viewed as a more defensive area - tended to underperform. Q What were the primary reasons for the Fund's underperformance of its benchmark, the Russell Index, during the six-month period ended September 30, 2017? A The Fund produced healthy absolute returns during the period, but lagged the return of the benchmark Russell Index, as we maintained our longer- term approach of emphasizing investments in fundamentally strong companies with high returns on growth capital, strong cash flow and earnings records, and reasonable stock prices. That resulted in our avoiding, or at least de-emphasizing, many of the better-performing, but very high-priced stocks that were the market's leaders over the six months. Some of those companies are in the outperforming industries and sectors we mentioned earlier, such as information technology and semiconductors. We also de-emphasized ownership of stocks of highly cyclical industrial companies, which nevertheless appreciated to price levels that seemed, to us, to reflect highly optimistic expectations for a strong re-acceleration of economic growth trends. Q Which individual investments had the largest effects on the Fund's benchmark-relative performance during the six-month period ended September 30, 2017, either from a positive or negative standpoint? A The most significant individual detractor from the Fund's benchmark- relative performance during the six-month period was a position in auto parts retailer O'Reilly Automotive. O'Reilly felt the effects of industry-wide sluggishness in sales, which we believe was the consequence of mild weather, particularly over the winter. However, we think O'Reilly has the potential to continue to expand market share against competitors, and we have maintained the Fund's position. We also retained the Fund's investment in Starbucks, another underperforming consumer discretionary company. Starbucks' growth appeared to slow during the period as the company struggled to fill customer orders during peak-demand times. We Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 5 think the well-managed company will solve those problems, however, as they actually are a consequence of the popularity of Starbucks' brand and products. We did sell the Fund's shares of another consumer discretionary stock that had disappointing performance during the period, Walt Disney. We think the iconic entertainment-and-theme park company's prospects are under threat from secular changes in the media industry, which have led to increased fragmentation and competition. Stock selection results in health care also tended to hold back the Fund's benchmark-relative returns during the period. Positions in the sector that detracted significantly from relative performance included specialty pharmaceutical company Allergan and medical device manufacturer Medtronic. Allergan underperformed due to market worries about the reliability of future profits from Restasis, a drug used in the treatment of dry eyes. We have maintained the Fund's Allergan investment, however, because of the company's market leadership in aesthetic and dermatology products as well as its promising drug pipeline. We also retained the position in Medtronic, which declined during the period because of lower-than-expected second-quarter results related to supply constraints on a sensor used in treating diabetes. We expect the supply issue to be resolved over the forthcoming quarters. Despite the Fund's benchmark-relative underperformance during the period, in what was a positive six months for large-cap stocks overall, several of the portfolio's holdings produced strong results, including positions in the financials, information technology, and industrials sectors. Among the top contributors to the Fund's benchmark-relative returns was financial-transaction processer Mastercard, which delivered strong results as it continued to expand in the global electronics processing business. Mastercard has continued to benefit from long-term secular changes as electronic payments replace cash and check transactions. Another strong contributor to the Fund's relative performance was a position in technology giant Alphabet, parent of Google. Alphabet sustained its growth trajectory from its internet search engine, while creating new opportunities in online video streaming, mapping, and the recently launched YouTube TV. In industrials, shares of Raytheon and Thermo Fisher Scientific were two standout performers for the Fund. Defense company Raytheon turned in strong earnings reports, while the outlook for global defense spending improved. Thermo Fisher also delivered impressive earnings results, while the company's acquisition strategy continued to contribute to its growth. In addition, even though some of the Fund's holdings within health care disappointed, as we noted earlier, shares of biotechnology company Vertex Pharmaceuticals outperformed during the period as the market recognized the potential of Vertex's developing products for the treatment of cystic fibrosis. 6 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 Q What were some of the notable changes you made to the Fund's portfolio during the six-month period ended September 30, 2017? A We added investments in several companies to the portfolio during the six months, including Cooper Industries, PayPal, Accenture, and Charles Schwab. Cooper Industries, which we believe we acquired at an attractive price, is a leading global manufacturer of contact lenses, with a particularly strong market position in specialty lenses, including multi-focal lenses. We think the company's recent investments in product development and manufacturing have positioned it to generate attractive growth and returns on capital. PayPal, meanwhile, has grown to a leadership position in online payments, taking advantage of some of the same secular trends that have benefited Mastercard. Accenture is a leading provider of management consulting, business process outsourcing, and technology services, whose experience throughout the world has given it a competitive advantage. Charles Schwab, meanwhile, has successfully expanded its asset management, brokerage, and banking businesses with a strong brand and significant scale and cost advantages, which have enhanced its competitive position. Sales from the portfolio during the period included shares of Kimberly Clark, Schlumberger, Nike, Reynolds American, and Walt Disney, which we discussed earlier. While Kimberly Clark has a prominent brand and is an efficiently managed company, its growth prospects have been affected by increased competition in the personal care industry, which is experiencing greater price pressures as companies fight for market share. We think those industry trends potentially could translate into lower returns on capital. We sold Nike, too, because of our concerns about increased competition. In addition, the company faces slowing growth in the global athletic footwear and apparel business, including in the United States. We liquidated the Fund's investment in oilfield-services firm Schlumberger because of our concerns over management's capital allocation decisions. Finally, we sold the Fund's position in tobacco company Reynolds American during its acquisition by British American Tobacco. Q Did the Fund have any investments in derivative securities during the six-month period ended September 30, 2017? A No, the Fund had no investments in any derivatives during the six-month period. Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 7 Q What is your investment outlook? A Consistent with our investment discipline, we have kept the Fund's portfolio positioned conservatively and continue to avoid many of the very high-valuation stocks. At period-end, the Fund is overweight in health care relative to the Russell Index, as we think stocks in the sector are attractively valued. We also have overweighted the financial services sector with positions in companies we believe can benefit from global growth trends. We have become more cautious about the equity market, even in the face of recent improvements in corporate earnings and the potential that pro- growth government fiscal policies, if enacted, could help sustain earnings growth in the coming year. Although current stock prices reflect a generally optimistic view that economic growth will improve further, there are significant risks. The risks include the possibility that the Fed might become more aggressive in tightening monetary policy should inflationary pressures finally begin to rise, that political gridlock in Washington could result in no fiscal stimulus, or that restrictive immigration and trade policies could negatively affect the economy. Moreover, geopolitical issues - most notably tensions with North Korea and Russia - could have negative effects on the markets. In addition, stock prices are high by historical comparisons. If one measures by trailing price-to-earnings ratios or by expected, future earnings, current equity prices seem to reflect a best-case scenario. In our view, however, the potential exists that more difficult times could lie ahead. We believe this is a good time to prepare for the possibility of more challenging market conditions ahead, and to maintain a portfolio that is conservatively positioned, with the potential to have lower downside volatility should current market trends reverse. 8 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 Please refer to the Schedule of Investments on pages 19-23 for a full listing of Fund securities. All investments are subject to risk, including the possible loss of principal. In the past several years, financial markets have experienced increased volatility, depressed valuations, decreased liquidity and heightened uncertainty. These conditions may continue, recur, worsen or spread. Investing in foreign and/or emerging markets securities involves risks relating to interest rates, currency exchange rates, economic, and political conditions. The Fund invests in a limited number of securities and, as a result, the Fund's performance may be more volatile than the performance of other funds holding more securities. At times, the Fund's investments may represent industries or industry sectors that are interrelated or have common risks, making the Fund more susceptible to any economic, political, or regulatory developments or other risks affecting those industries and sectors. These risks may increase share price volatility. Before investing, consider the product's investment objectives, risks, charges and expenses. Contact your advisor or Amundi Pioneer Asset Management, Inc., for a prospectus or summary prospectus containing this information. Read it carefully. Any information in this shareholder report regarding market or economic trends or the factors influencing the Fund's historical or future performance are statements of opinion as of the date of this report. Past performance is no guarantee of future results. Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 9 Portfolio Summary | 9/30/17 Portfolio Diversification -------------------------------------------------------------------------------- (As a percentage of total investment portfolio) [THE FOLLOWING DATA WAS REPRESENTED AS A PIE CHART IN THE PRINTED MATERIAL] U.S. Common Stocks 90.7% International Common Stocks 6.3% U.S. Government Securities 2.5% Temporary Cash Investment 0.5% Sector Distribution -------------------------------------------------------------------------------- (As a percentage of equity holdings) [THE FOLLOWING DATA WAS REPRESENTED AS A PIE CHART IN THE PRINTED MATERIAL] Information Technology 37.1% Health Care 18.0% Consumer Discretionary 15.0% Financials 10.2% Consumer Staples 9.0% Industrials 6.1% Materials 2.7% Energy 1.9% 10 Largest Holdings -------------------------------------------------------------------------------- (As a percentage of equity holdings)* 1. Apple, Inc. 6.69% -------------------------------------------------------------------------------- 2. Microsoft Corp. 6.67 -------------------------------------------------------------------------------- 3. Alphabet, Inc. 6.40 -------------------------------------------------------------------------------- 4. Mastercard, Inc. 4.91 -------------------------------------------------------------------------------- 5. The Home Depot, Inc. 4.53 -------------------------------------------------------------------------------- 6. Thermo Fisher Scientific, Inc. 3.74 -------------------------------------------------------------------------------- 7. Intercontinental Exchange, Inc. 3.36 -------------------------------------------------------------------------------- 8. CVS Health Corp. 3.23 -------------------------------------------------------------------------------- 9. Amazon.com, Inc. 3.22 -------------------------------------------------------------------------------- 10. Time Warner, Inc. 3.12 -------------------------------------------------------------------------------- * This list excludes temporary cash investments and derivative instruments. The Fund is actively managed, and current holdings may be different. The holdings listed should not be considered recommendations to buy or sell any securities listed. 10 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 Prices and Distributions | 9/30/17 Net Asset Value per Share -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Class 9/30/17 3/31/17 -------------------------------------------------------------------------------- A $22.57 $20.78 -------------------------------------------------------------------------------- C $20.76 $19.17 -------------------------------------------------------------------------------- K $22.64 $20.79 -------------------------------------------------------------------------------- R $22.23 $20.49 -------------------------------------------------------------------------------- Y $22.80 $20.95 -------------------------------------------------------------------------------- Distributions per Share: 4/1/17-9/30/17 -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Short-Term Long-Term Class Dividends Capital Gains Capital Gains -------------------------------------------------------------------------------- A $ -- $ -- $ -- -------------------------------------------------------------------------------- C $ -- $ -- $ -- -------------------------------------------------------------------------------- K $ -- $ -- $ -- -------------------------------------------------------------------------------- R $ -- $ -- $ -- -------------------------------------------------------------------------------- Y $ -- $ -- $ -- -------------------------------------------------------------------------------- The Russell 1000 Growth Index is an unmanaged index that measures the performance of large-cap U.S. growth stocks. Index returns assume reinvestment of dividends and, unlike Fund returns, do not reflect any fees, expenses or sales charges. It is not possible to invest directly in an index. The index defined here pertains to the "Value of $10,000 Investment" and "Value of $5 Million Investment" charts on pages 12-16. Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 11 Performance Update | 9/30/17 Class A Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $10,000 investment made in Class A shares of Pioneer Fundamental Growth Fund at public offering price during the periods shown, compared to that of the Russell 1000 Growth Index. Average Annual Total Returns (As of September 30, 2017) -------------------------------------------------------------------------------- Net Public Russell Asset Offering 1000 Value Price Growth Period (NAV) (POP) Index -------------------------------------------------------------------------------- 10 years 9.13% 8.48% 9.08% 5 years 13.87 12.53 15.26 1 year 17.63 10.85 21.94 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated August 1, 2017) -------------------------------------------------------------------------------- Gross -------------------------------------------------------------------------------- 1.09% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Pioneer Fundamental Russell 1000 Growth Fund Growth Index 9/07 $ 9,425 $10,000 9/08 $ 7,949 $ 7,912 9/09 $ 7,999 $ 7,766 9/10 $ 8,680 $ 8,748 9/11 $ 9,149 $ 9,079 9/12 $11,789 $11,728 9/13 $13,728 $13,989 9/14 $16,414 $16,668 9/15 $17,285 $17,197 9/16 $19,187 $19,103 9/17 $22,569 $23,855 Call 1-800-225-6292 or visit www.amundipioneer.com for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted. The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost. NAV results represent the percent change in net asset value per share. Returns would have been lower had sales charges been reflected. POP returns reflect deduction of maximum 5.75% sales charge. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ. Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. Please refer to the financial highlights for a more current expense ratio. 12 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 Performance Update | 9/30/17 Class C Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $10,000 investment made in Class C shares of Pioneer Fundamental Growth Fund during the periods shown, compared to that of the Russell 1000 Growth Index. Average Annual Total Returns (As of September 30, 2017) -------------------------------------------------------------------------------- Russell 1000 If If Growth Period Held Redeemed Index -------------------------------------------------------------------------------- 10 years 8.30% 8.30% 9.08% 5 years 13.08 13.08 15.26 1 year 16.87 16.87 21.94 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated August 1, 2017) -------------------------------------------------------------------------------- Gross -------------------------------------------------------------------------------- 1.77% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Pioneer Fundamental Russell 1000 Growth Fund Growth Index 9/07 $10,000 $10,000 9/08 $ 8,360 $ 7,912 9/09 $ 8,347 $ 7,766 9/10 $ 8,980 $ 8,748 9/11 $ 9,398 $ 9,079 9/12 $12,010 $11,728 9/13 $13,884 $13,989 9/14 $16,475 $16,668 9/15 $17,232 $17,197 9/16 $18,997 $19,103 9/17 $22,203 $23,855 Call 1-800-225-6292 or visit www.amundipioneer.com for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted. The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost. Class C shares held for less than one year are also subject to a 1% contingent deferred sales charge (CDSC). "If Held" results represent the percent change in net asset value per share. Returns would have been lower had sales charges been reflected. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ. Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. Please refer to the financial highlights for a more current expense ratio. Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 13 Performance Update | 9/30/17 Class K Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $5 million investment made in Class K shares of Pioneer Fundamental Growth Fund during the periods shown, compared to that of the Russell 1000 Growth Index. Average Annual Total Returns (As of September 30, 2017) -------------------------------------------------------------------------------- Net Russell Asset 1000 Value Growth Period (NAV) Index -------------------------------------------------------------------------------- 10 years 9.35% 9.08% 5 years 14.33 15.26 1 year 18.18 21.94 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated August 1, 2017) -------------------------------------------------------------------------------- Gross -------------------------------------------------------------------------------- 0.67% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $5 Million Investment Pioneer Fundamental Russell 1000 Growth Fund Growth Index 9/07 $ 5,000,000 $ 5,000,000 9/08 $ 4,216,982 $ 3,956,080 9/09 $ 4,243,463 $ 3,882,773 9/10 $ 4,604,803 $ 4,374,010 9/11 $ 4,853,730 $ 4,539,278 9/12 $ 6,254,134 $ 5,864,209 9/13 $ 7,307,446 $ 6,994,516 9/14 $ 8,766,999 $ 8,333,796 9/15 $ 9,275,956 $ 8,598,261 9/16 $10,338,055 $ 9,781,437 9/17 $12,217,747 $11,927,552 Call 1-800-225-6292 or visit www.amundipioneer.com for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted. The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost. The performance shown for Class K shares for the period prior to the commencement of operations of Class K shares on December 20, 2012, is the net asset value performance of the Fund's Class A shares, which has not been restated to reflect any differences in expenses, including Rule 12b-1 fees applicable to Class A shares. Since fees for Class A shares generally are higher than those of Class K shares, the performance of Class K shares prior to their inception would have been higher than the performance shown. For the period beginning December 20, 2012, the actual performance of Class K shares is reflected. Class K shares are not subject to sales charges and are available for limited groups of eligible investors, including institutional investors. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ. Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. Please refer to the financial highlights for a more current expense ratio. 14 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 Performance Update | 9/30/17 Class R Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $10,000 investment made in Class R shares of Pioneer Fundamental Growth Fund during the periods shown, compared to that of the Russell 1000 Growth Index. Average Annual Total Returns (As of September 30, 2017) -------------------------------------------------------------------------------- Net Russell Asset 1000 Value Growth Period (NAV) Index -------------------------------------------------------------------------------- 10 years 8.95% 9.08% 5 years 13.54 15.26 1 year 17.30 21.94 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated August 1, 2017) -------------------------------------------------------------------------------- Gross Net -------------------------------------------------------------------------------- 1.41% 1.40% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Pioneer Fundamental Russell 1000 Growth Fund Growth Index 9/07 $10,000 $10,000 9/08 $ 8,434 $ 7,912 9/09 $ 8,487 $ 7,766 9/10 $ 9,210 $ 8,748 9/11 $ 9,707 $ 9,079 9/12 $12,490 $11,728 9/13 $14,502 $13,989 9/14 $17,292 $16,668 9/15 $18,153 $17,197 9/16 $20,089 $19,103 9/17 $23,565 $23,855 Call 1-800-225-6292 or visit www.amundipioneer.com for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted. The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost. The performance shown for Class R shares for the period prior to the commencement of operations of Class R shares on April 2, 2012, is based on the performance of Class A shares, reduced to reflect the higher distribution and service fees of Class R shares. For the period beginning April 2, 2012, the actual performance of Class R shares is reflected. Class R shares are not subject to sales charges and are available for limited groups of eligible investors, including institutional investors. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ. Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information. The net expense ratio reflects the contractual expense limitation currently in effect through August 1, 2018, for Class R shares. There can be no assurance that Amundi Pioneer will extend the expense limitation beyond such time. Please see the prospectus and financial statements for more information. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. Please refer to the financial highlights for a more current expense ratio. Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 15 Performance Update | 9/30/17 Class Y Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $5 million investment made in Class Y shares of Pioneer Fundamental Growth Fund during the periods shown, compared to that of the Russell 1000 Growth Index. Average Annual Total Returns (As of September 30, 2017) -------------------------------------------------------------------------------- Net Russell Asset 1000 Value Growth Period (NAV) Index -------------------------------------------------------------------------------- 10 years 9.45% 9.08% 5 years 14.22 15.26 1 year 18.01 21.94 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated August 1, 2017) -------------------------------------------------------------------------------- Gross -------------------------------------------------------------------------------- 0.77% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $5 Million Investment Pioneer Fundamental Russell 1000 Growth Fund Growth Index 9/07 $ 5,000,000 $ 5,000,000 9/08 $ 4,216,982 $ 3,956,080 9/09 $ 4,255,763 $ 3,882,773 9/10 $ 4,630,172 $ 4,374,010 9/11 $ 4,908,071 $ 4,539,278 9/12 $ 6,343,053 $ 5,864,209 9/13 $ 7,406,226 $ 6,994,516 9/14 $ 8,879,408 $ 8,333,796 9/15 $ 9,382,383 $ 8,598,261 9/16 $10,449,504 $ 9,781,437 9/17 $12,331,234 $11,927,552 Call 1-800-225-6292 or visit www.amundipioneer.com for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted. The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost. The performance shown for Class Y shares for the period prior to the commencement of operations of Class Y shares on April 8, 2009, is the net asset value performance of the Fund's Class A shares, which has not been restated to reflect any differences in expenses, including Rule 12b-1 fees applicable to Class A shares. Since fees for Class A shares generally are higher than those of Class Y shares, the performance of Class Y shares prior to their inception would have been higher than the performance shown. For the period beginning April 8, 2009, the actual performance of Class Y shares is reflected. Class Y shares are not subject to sales charges and are available for limited groups of eligible investors, including institutional investors. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ. Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. Please refer to the financial highlights for a more current expense ratio. 16 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 Comparing Ongoing Fund Expenses As a shareowner in the Fund, you incur two types of costs: (1) ongoing costs, including management fees, distribution and/or service (12b-1) fees, and other Fund expenses; and (2) transaction costs, including sales charges (loads) on purchase payments. This example is intended to help you understand your ongoing expenses (in dollars) of investing in the Fund and to compare these costs with the ongoing costs of investing in other mutual funds. The example is based on an investment of $1,000 at the beginning of the Fund's latest six-month period and held throughout the six months. Using the Tables -------------------------------------------------------------------------------- Actual Expenses The first table below provides information about actual account values and actual expenses. You may use the information in this table, together with the amount you invested, to estimate the expenses that you paid over the period as follows: (1) Divide your account value by $1,000 Example: an $8,600 account value (divided by) $1,000 = 8.6 (2) Multiply the result in (1) above by the corresponding share class's number in the third row under the heading entitled "Expenses Paid During Period" to estimate the expenses you paid on your account during this period. Expenses Paid on a $1,000 Investment in Pioneer Fundamental Growth Fund Based on actual returns from April 1, 2017, through September 30, 2017. -------------------------------------------------------------------------------- Share Class A C K R Y -------------------------------------------------------------------------------- Beginning Account $1,000.00 $1,000.00 $1,000.00 $1,000.00 $1,000.00 Value on 4/1/17 -------------------------------------------------------------------------------- Ending Account $1,086.10 $1,082.90 $1,089.00 $1,084.90 $1,088.30 Value (after expenses) on 9/30/17 -------------------------------------------------------------------------------- Expenses Paid $ 5.70 $ 9.14 $ 3.46 $ 7.26 $ 4.08 During Period* -------------------------------------------------------------------------------- * Expenses are equal to the Fund's annualized expense ratio of 1.09%, 1.75%, 0.66% 1.39% and 0.78% for Class A, Class C, Class K, Class R and Class Y shares, respectively, multiplied by the average account value over the period, multiplied by 183/365 (to reflect the partial year period). Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 17 Hypothetical Example for Comparison Purposes The table below provides information about hypothetical account values and hypothetical expenses based on the Fund's actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the Fund's actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. You may use this information to compare the ongoing costs of investing in the Fund and other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other funds. Please note that the expenses shown in the tables are meant to highlight your ongoing costs only and do not reflect any transaction costs, such as sales charges (loads) that are charged at the time of the transaction. Therefore, the table below is useful in comparing ongoing costs only and will not help you determine the relative total costs of owning different funds. In addition, if these transaction costs were included, your costs would have been higher. Expenses Paid on a $1,000 Investment in Pioneer Fundamental Growth Fund Based on a hypothetical 5% per year return before expenses, reflecting the period from April 1, 2017, through September 30, 2017. -------------------------------------------------------------------------------- Share Class A C K R Y -------------------------------------------------------------------------------- Beginning Account $1,000.00 $1,000.00 $1,000.00 $1,000.00 $1,000.00 Value on 4/1/17 -------------------------------------------------------------------------------- Ending Account $1,019.60 $1,016.29 $1,021.76 $1,018.10 $1,021.16 Value (after expenses) on 9/30/17 -------------------------------------------------------------------------------- Expenses Paid $ 5.52 $ 8.85 $ 3.35 $ 7.03 $ 3.95 During Period* -------------------------------------------------------------------------------- * Expenses are equal to the Fund's annualized expense ratio of 1.09%, 1.75%, 0.66% 1.39% and 0.78% for Class A, Class C, Class K, Class R and Class Y shares, respectively, multiplied by the average account value over the period, multiplied by 183/365 (to reflect the partial year period). 18 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 Schedule of Investments | 9/30/17 (unaudited) ---------------------------------------------------------------------------------------- Shares Value ---------------------------------------------------------------------------------------- UNAFFILIATED ISSUERS -- 100.3% COMMON STOCKS -- 97.5% ENERGY -- 1.4% Oil & Gas Exploration & Production -- 1.4% 3,222,975 Cabot Oil & Gas Corp. $ 86,214,581 -------------- Total Energy $ 86,214,581 ---------------------------------------------------------------------------------------- MATERIALS -- 2.8% Specialty Chemicals -- 2.8% 748,491 Ecolab, Inc. $ 96,263,428 524,380 International Flavors & Fragrances, Inc. 74,939,146 -------------- $ 171,202,574 -------------- Total Materials $ 171,202,574 ---------------------------------------------------------------------------------------- CAPITAL GOODS -- 6.2% Aerospace & Defense -- 4.5% 1,016,775 Raytheon Co. $ 189,709,880 747,771 United Technologies Corp. 86,801,258 -------------- $ 276,511,138 ---------------------------------------------------------------------------------------- Building Products -- 1.7% 2,592,205 Masco Corp. $ 101,121,917 -------------- Total Capital Goods $ 377,633,055 ---------------------------------------------------------------------------------------- CONSUMER SERVICES -- 1.7% Restaurants -- 1.7% 1,965,973 Starbucks Corp. $ 105,592,410 -------------- Total Consumer Services $ 105,592,410 ---------------------------------------------------------------------------------------- MEDIA -- 3.1% Movies & Entertainment -- 3.1% 1,859,621 Time Warner, Inc. $ 190,518,171 -------------- Total Media $ 190,518,171 ---------------------------------------------------------------------------------------- RETAILING -- 10.3% Internet Retail -- 3.2% 204,643 Amazon.com, Inc. * $ 196,733,548 ---------------------------------------------------------------------------------------- Apparel Retail -- 1.7% 1,571,418 Ross Stores, Inc. $ 101,466,460 ---------------------------------------------------------------------------------------- Home Improvement Retail -- 4.5% 1,694,393 The Home Depot, Inc. $ 277,134,919 ---------------------------------------------------------------------------------------- Automotive Retail -- 0.9% 236,512 O'Reilly Automotive, Inc. * $ 50,937,589 -------------- Total Retailing $ 626,272,516 ---------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 19 Schedule of Investments | 9/30/17 (unaudited) (continued) ---------------------------------------------------------------------------------------- Shares Value ---------------------------------------------------------------------------------------- FOOD & STAPLES RETAILING -- 3.2% Drug Retail -- 3.2% 2,425,598 CVS Health Corp. $ 197,249,629 -------------- Total Food & Staples Retailing $ 197,249,629 ---------------------------------------------------------------------------------------- FOOD, BEVERAGE & TOBACCO -- 4.4% Soft Drinks -- 3.0% 1,613,573 PepsiCo., Inc. $ 179,800,439 ---------------------------------------------------------------------------------------- Packaged Foods & Meats -- 1.4% 800,757 The Hershey Co. $ 87,418,642 -------------- Total Food, Beverage & Tobacco $ 267,219,081 ---------------------------------------------------------------------------------------- HOUSEHOLD & PERSONAL PRODUCTS -- 1.5% Household Products -- 1.5% 1,239,480 Colgate-Palmolive Co. $ 90,296,118 -------------- Total Household & Personal Products $ 90,296,118 ---------------------------------------------------------------------------------------- HEALTH CARE EQUIPMENT & SERVICES -- 4.6% Health Care Equipment -- 2.6% 377,262 Edwards Lifesciences Corp. * $ 41,238,509 1,497,910 Medtronic PLC 116,492,461 -------------- $ 157,730,970 ---------------------------------------------------------------------------------------- Health Care Supplies -- 2.0% 506,441 The Cooper Companies, Inc. $ 120,082,226 -------------- Total Health Care Equipment & Services $ 277,813,196 ---------------------------------------------------------------------------------------- PHARMACEUTICALS, BIOTECHNOLOGY & LIFE SCIENCES -- 13.5% Biotechnology -- 5.0% 847,834 Celgene Corp. * $ 123,631,154 1,490,837 Gilead Sciences, Inc. * 120,787,614 406,619 Vertex Pharmaceuticals, Inc. * 61,822,353 -------------- $ 306,241,121 ---------------------------------------------------------------------------------------- Pharmaceuticals -- 4.8% 728,843 Allergan Plc $ 149,376,373 1,097,314 Johnson & Johnson 142,661,793 -------------- $ 292,038,166 ---------------------------------------------------------------------------------------- Life Sciences Tools & Services -- 3.7% 1,208,281 Thermo Fisher Scientific, Inc. $ 228,606,765 -------------- Total Pharmaceuticals, Biotechnology & Life Sciences $ 826,886,052 ---------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 20 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 ---------------------------------------------------------------------------------------- Shares Value ---------------------------------------------------------------------------------------- DIVERSIFIED FINANCIALS -- 4.7% Investment Banking & Brokerage -- 1.3% 1,898,596 The Charles Schwab Corp. $ 83,044,589 ---------------------------------------------------------------------------------------- Specialized Finance -- 3.4% 2,991,895 Intercontinental Exchange, Inc. $ 205,543,186 -------------- Total Diversified Financials $ 288,587,775 ---------------------------------------------------------------------------------------- INSURANCE -- 3.0% Insurance Brokers -- 3.0% 2,178,063 Marsh & McLennan Companies, Inc. $ 182,543,460 -------------- Total Insurance $ 182,543,460 ---------------------------------------------------------------------------------------- SOFTWARE & SERVICES -- 26.0% Internet Software & Services -- 6.4% 408,017 Alphabet, Inc. (Class C) $ 391,333,185 ---------------------------------------------------------------------------------------- IT Consulting & Other Services -- 3.0% 557,819 Accenture Plc $ 75,344,612 1,511,900 Cognizant Technology Solutions Corp. * 109,673,226 -------------- $ 185,017,838 ---------------------------------------------------------------------------------------- Data Processing & Outsourced Services -- 7.5% 2,124,394 Mastercard, Inc. $ 299,964,433 2,503,713 PayPal Holdings, Inc. 160,312,743 -------------- $ 460,277,176 ---------------------------------------------------------------------------------------- Application Software -- 2.4% 977,980 Adobe Systems, Inc. * $ 145,895,056 ---------------------------------------------------------------------------------------- Systems Software -- 6.7% 5,476,821 Microsoft Corp. $ 407,968,396 -------------- Total Software & Services $1,590,491,651 ---------------------------------------------------------------------------------------- TECHNOLOGY HARDWARE & EQUIPMENT -- 8.4% Computer Storage & Peripherals -- 6.7% 2,655,676 Apple, Inc. $ 409,292,786 ---------------------------------------------------------------------------------------- Electronic Components -- 1.7% 1,261,077 Amphenol Corp. $ 106,737,557 -------------- Total Technology Hardware & Equipment $ 516,030,343 ---------------------------------------------------------------------------------------- SEMICONDUCTORS & SEMICONDUCTOR EQUIPMENT -- 2.7% Semiconductors -- 2.7% 685,685 Broadcom, Ltd. $ 166,306,040 -------------- Total Semiconductors & Semiconductor Equipment $ 166,306,040 ---------------------------------------------------------------------------------------- TOTAL COMMON STOCKS (Cost $4,507,289,745) $5,960,856,652 ---------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 21 Schedule of Investments | 9/30/17 (unaudited) (continued) ----------------------------------------------------------------------------------------- Principal Amount ($) Value ----------------------------------------------------------------------------------------- U.S. GOVERNMENT AND AGENCY OBLIGATIONS -- 2.5% 88,670,000 U.S. Treasury Bills, 10/19/17 (a) $ 88,631,531 65,115,000 U.S. Treasury Bills, 10/26/17 (a) 65,074,357 --------------- $ 153,705,888 ----------------------------------------------------------------------------------------- TOTAL U.S. GOVERNMENT AND AGENCY OBLIGATIONS (Cost $153,700,580) $ 153,705,888 ----------------------------------------------------------------------------------------- TEMPORARY CASH INVESTMENT -- 0.3% Repurchase Agreement -- 0.3% 19,645,000 $19,645,000 ScotiaBank, 1.05%, dated 9/29/17 plus accrued interest on 10/2/17 collateralized by $20,039,654 Federal National Mortgage Association, 4.0%, 9/1/47 $ 19,645,000 ----------------------------------------------------------------------------------------- TOTAL TEMPORARY CASH INVESTMENT (Cost $19,645,000) $ 19,645,000 ----------------------------------------------------------------------------------------- TOTAL INVESTMENT IN UNAFFILIATED ISSUERS -- 100.3% (Cost $4,680,635,325) $6,134,207,540 ----------------------------------------------------------------------------------------- OTHER ASSETS & LIABILITIES -- (0.3)% $ (15,954,060) ----------------------------------------------------------------------------------------- TOTAL NET ASSETS -- 100.0% $6,118,253,480 ========================================================================================= * Non-income producing security. (a) Security issued with a zero coupon. Income is earned through accretion of discount. Purchases and sales of securities (excluding temporary cash investments) for the six months ended September 30, 2017, aggregated $979,106,887 and $876,177,939, respectively. The Fund is permitted to engage in purchase and sale transactions ("cross trades") with certain Funds and accounts for which Amundi Pioneer Asset Management, Inc., formerly Pioneer Investment Management, Inc. (the "Adviser") serves as investment adviser, as set forth in Rule 17a-7 under the Investment Company Act of 1940, pursuant to procedures adopted by the Board of Trustees. Under these procedures, cross trades are effected at current market prices. During the six months ended September 30, 2017, the Fund did not engage in any cross trade activity. At September 30, 2017, the net unrealized appreciation on investments based on cost for federal income tax purposes of $4,688,949,441 was as follows: Aggregate gross unrealized appreciation for all investments in which there is an excess of value over tax cost $1,493,747,487 Aggregate gross unrealized depreciation for all investments in which there is an excess of tax cost over value (48,489,388) -------------- Net unrealized appreciation $1,445,258,099 ============== Various inputs are used in determining the value of the Fund's investments. These inputs are summarized in the three broad levels listed below. Level 1 - quoted prices in active markets for identical securities. Level 2 - other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risk, etc.) See Notes to Financial Statements -- Note 1A. Level 3 - significant unobservable inputs (including the Fund's own assumptions in determining fair value of investments) See Notes to Financial Statements -- Note 1A. The accompanying notes are an integral part of these financial statements. 22 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 The following is a summary of the inputs used as of September 30, 2017, in valuing the Fund's investments: -------------------------------------------------------------------------------- Level 1 Level 2 Level 3 Total -------------------------------------------------------------------------------- Common Stocks $5,960,856,652 $ -- $ -- $5,960,856,652 U.S. Government and Agency Obligations -- 153,705,888 -- 153,705,888 Repurchase Agreement -- 19,645,000 -- 19,645,000 -------------------------------------------------------------------------------- Total $5,960,856,652 $173,350,888 $ -- $6,134,207,540 ================================================================================ The accompanying notes are an integral part of these financial statements. Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 23 Statement of Assets and Liabilities | 9/30/17 (unaudited) ASSETS: Investment in unaffiliated issuers, at value (cost $4,680,635,325) $6,134,207,540 Cash 5,416,637 Receivables -- Fund shares sold 11,714,576 Dividends 2,082,954 Interest 1,146 Due from the Adviser 4,196 Other assets 110,612 ------------------------------------------------------------------------------------ Total assets $6,153,537,661 ------------------------------------------------------------------------------------ LIABILITIES: Payables -- Investment securities purchased $ 21,015,983 Fund shares repurchased 11,791,336 Trustee fees 6,734 Due to affiliates 1,022,469 Accrued expenses 1,447,659 ------------------------------------------------------------------------------------ Total liabilities $ 35,284,181 ------------------------------------------------------------------------------------ NET ASSETS: Paid-in capital $4,468,121,371 Undistributed net investment income 17,257,991 Accumulated net realized gain on investments 179,301,903 Net unrealized appreciation on investments 1,453,572,215 ------------------------------------------------------------------------------------ Net assets $6,118,253,480 ------------------------------------------------------------------------------------ NET ASSET VALUE PER SHARE: (No par value, unlimited number of shares authorized) Class A (based on $1,258,344,326/55,746,857 shares) $ 22.57 Class C (based on $472,610,926/22,767,620 shares) $ 20.76 Class K (based on $515,564,802/22,775,653 shares) $ 22.64 Class R (based on $149,976,343/6,746,242 shares) $ 22.23 Class Y (based on $3,721,757,083/163,244,888 shares) $ 22.80 MAXIMUM OFFERING PRICE: Class A ($22.57 (divided by) 94.25%) $ 23.95 ==================================================================================== The accompanying notes are an integral part of these financial statements. 24 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 Statement of Operations (unaudited) For the Six Months Ended 9/30/17 INVESTMENT INCOME: Interest from unaffiliated issuers $ 550,982 Dividends from unaffiliated issuers 38,714,080 ------------------------------------------------------------------------------------ Total investment income $ 39,265,062 ==================================================================================== EXPENSES: Management fees $17,935,893 Transfer agent fees Class A 1,244,475 Class C 206,826 Class K 1,572 Class R 162,191 Class Y 2,111,344 Distribution fees Class A 1,570,824 Class C 2,373,564 Class R 355,479 Shareholder communications expense 145,752 Administrative expense 857,313 Custodian fees 38,476 Registration fees 123,021 Professional fees 82,206 Printing expense 28,222 Fees and expenses of nonaffiliated Trustees 145,273 Miscellaneous 48,940 ------------------------------------------------------------------------------------ Total expenses $ 27,431,371 ------------------------------------------------------------------------------------ Less fees waived and expenses reimbursed the Adviser (116,763) Net expenses $ 27,314,608 ------------------------------------------------------------------------------------ Net investment income $ 11,950,454 ------------------------------------------------------------------------------------ REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS: Net realized gain (loss) on: Investments from unaffiliated issuers $124,099,361 Change in net unrealized appreciation (depreciation) on: Investments from unaffiliated issuers $350,400,730 ------------------------------------------------------------------------------------ Net realized and unrealized gain (loss) on investments $474,500,091 ------------------------------------------------------------------------------------ Net increase in net assets resulting from operations $486,450,545 ==================================================================================== The accompanying notes are an integral part of these financial statements. Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 25 Statements of Changes in Net Assets --------------------------------------------------------------------------------------------- Six Months Ended 9/30/17 Year Ended (unaudited) 3/31/17 --------------------------------------------------------------------------------------------- FROM OPERATIONS: Net investment income (loss) $ 11,950,454 $ 23,782,066 Net realized gain (loss) on investments 124,099,361 156,719,815 Change in net unrealized appreciation (depreciation) on investments 350,400,730 367,209,601 --------------------------------------------------------------------------------------------- Net increase in net assets resulting from operations $ 486,450,545 $ 547,711,482 --------------------------------------------------------------------------------------------- DISTRIBUTIONS TO SHAREOWNERS: Net investment income: Class A ($0.00 and $0.06 per share, respectively) $ -- $ (3,454,370) Class K ($0.00 and $0.13 per share, respectively) -- (1,872,933) Class R ($0.00 and $0.01 per share, respectively) -- (67,393) Class Y ($0.00 and $0.11 per share, respectively) -- (17,013,709) Net realized gain: Class A ($0.00 and $0.37 per share, respectively) -- (21,901,386) Class C ($0.00 and $0.37 per share, respectively) -- (8,702,792) Class K ($0.00 and $0.37 per share, respectively) -- (5,095,362) Class R ($0.00 and $0.37 per share, respectively) -- (1,980,050) Class Y ($0.00 and $0.37 per share, respectively) -- (52,838,090) --------------------------------------------------------------------------------------------- Total distributions to shareowners $ -- $ (112,926,085) --------------------------------------------------------------------------------------------- FROM FUND SHARE TRANSACTIONS: Net proceeds from sale of shares $1,074,761,417 $2,907,428,317 Reinvestment of distributions -- 95,432,134 Cost of shares repurchased (807,127,908) (1,635,411,826) --------------------------------------------------------------------------------------------- Net increase in net assets resulting from Fund share transactions $ 267,633,509 $1,367,448,625 --------------------------------------------------------------------------------------------- Net increase in net assets $ 754,084,054 $1,802,234,022 NET ASSETS: Beginning of period 5,364,169,426 3,561,935,404 --------------------------------------------------------------------------------------------- End of period $6,118,253,480 $5,364,169,426 --------------------------------------------------------------------------------------------- Undistributed net investment income $ 17,257,991 $ 5,307,537 ============================================================================================= The accompanying notes are an integral part of these financial statements. 26 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 ----------------------------------------------------------------------------------------------- Six Months Six Months Ended Ended 9/30/17 9/30/17 Year Ended Year Ended Shares Amount 3/31/17 3/31/17 (unaudited) (unaudited) Shares Amount ----------------------------------------------------------------------------------------------- Class A Shares sold 8,583,566 $ 186,751,963 28,290,513 $ 548,519,293 Reinvestment of distributions -- 1,134,495 21,758,157 Less shares repurchased (10,835,033) (236,983,949) (23,684,612) (464,790,618) ----------------------------------------------------------------------------------------------- Net increase (decrease) (2,251,467) $ (50,231,986) 5,740,396 $ 105,486,832 =============================================================================================== Class C Shares sold 2,109,387 $ 42,248,723 8,891,081 $ 159,283,437 Reinvestment of distributions -- -- 407,641 7,194,885 Less shares repurchased (3,624,443) (72,726,003) (5,248,783) (94,992,423) ----------------------------------------------------------------------------------------------- Net increase (decrease) (1,515,056) $ (30,477,280) 4,049,939 $ 71,485,899 =============================================================================================== Class K Shares sold 6,286,865 $ 136,325,706 14,720,842 $ 287,184,419 Reinvestment of distributions -- -- 322,783 6,217,263 Less shares repurchased (1,629,137) (35,751,050) (3,862,478) (75,263,475) ----------------------------------------------------------------------------------------------- Net increase 4,657,728 $ 100,574,656 11,181,147 $ 218,138,207 =============================================================================================== Class R Shares sold 1,888,095 $ 40,078,641 2,975,998 $ 56,835,178 Reinvestment of distributions -- -- 62,318 1,175,352 Less shares repurchased (896,261) (19,366,207) (1,522,340) (29,269,528) ----------------------------------------------------------------------------------------------- Net increase 991,834 $ 20,712,434 1,515,976 $ 28,741,002 =============================================================================================== Class Y Shares sold 30,612,989 $ 669,356,384 94,425,176 $1,855,605,990 Reinvestment of distributions -- -- 3,046,171 59,086,477 Less shares repurchased (20,031,709) (442,300,699) (49,292,166) (971,095,782) ----------------------------------------------------------------------------------------------- Net increase 10,581,280 $ 227,055,685 48,179,181 $ 943,596,685 =============================================================================================== The accompanying notes are an integral part of these financial statements. Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 27 Financial Highlights ------------------------------------------------------------------------------------------------------------------------------------ Six Months Ended Year Year Year Year Year 9/30/17 Ended Ended Ended Ended Ended (unaudited) 3/31/17 3/31/16 3/31/15 3/31/14 3/31/13 ------------------------------------------------------------------------------------------------------------------------------------ Class A Net asset value, beginning of period $ 20.78 $ 19.00 $ 19.06 $ 16.66 $ 14.33 $ 13.23 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ 0.03(a) $ 0.08(a) $ 0.07(a) $ 0.06 $ 0.06 $ 0.07 Net realized and unrealized gain (loss) on investments 1.76 2.13 0.70 2.86 2.95 1.20 ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $ 1.79 $ 2.21 $ 0.77 $ 2.92 $ 3.01 $ 1.27 ------------------------------------------------------------------------------------------------------------------------------------ Distribution to shareowners: Net investment income $ -- $ (0.06) $ (0.05) $ (0.05) $ (0.06) $ (0.06) Net realized gain -- (0.37) (0.78) (0.47) (0.62) (0.11) ------------------------------------------------------------------------------------------------------------------------------------ Total distributions $ -- $ (0.43) $ (0.83) $ (0.52) $ (0.68) $ (0.17) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ 1.79 $ 1.78 $ (0.06) $ 2.40 $ 2.33 $ 1.10 ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 22.57 $ 20.78 $ 19.00 $ 19.06 $ 16.66 $ 14.33 ==================================================================================================================================== Total return* 8.61% 11.78% 4.00% 17.60% 21.16% 9.64% Ratio of net expenses to average net assets 1.09%** 1.09% 1.09% 1.09% 1.08% 1.09% Ratio of net investment income (loss) to average net assets 0.24%** 0.39% 0.38% 0.38% 0.46% 0.54% Portfolio turnover rate 30%** 23% 13% 12% 21% 28% Net assets, end of period (in thousands) $ 1,258,344 $1,205,124 $992,927 $796,689 $644,527 $436,682 Ratios with no waiver of fees and assumption of expenses by the Adviser and no reduction for fees paid indirectly: Total expenses to average net assets 1.11%** 1.09% 1.11% 1.13% 1.13% 1.20% Net investment income (loss) to average net assets 0.22%** 0.39% 0.36% 0.34% 0.41% 0.43% ==================================================================================================================================== * Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions, the complete redemption of the investment at net asset value at the end of each period and no sales charges. Total return would be reduced if sales charges were taken into account. ** Annualized. (a) The per-share data presented above is based on the average shares outstanding for the period presented. The accompanying notes are an integral part of these financial statements. 28 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 ------------------------------------------------------------------------------------------------------------------------------------ Six Months Ended Year Year Year Year Year 9/30/17 Ended Ended Ended Ended Ended (unaudited) 3/31/17 3/31/16 3/31/15 3/31/14 3/31/13 ------------------------------------------------------------------------------------------------------------------------------------ Class C Net asset value, beginning of period $ 19.17 $ 17.63 $ 17.81 $ 15.66 $ 13.55 $ 12.57 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ (0.04)(a)(b) $ (0.05)(a)(b) $ (0.05)(a)(b) $ (0.03) $ (0.04) $ (0.02)(a) Net realized and unrealized gain (loss) on investments 1.63 1.96 0.65 2.65 2.77 1.12 ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $ 1.59 $ 1.91 $ 0.60 $ 2.62 $ 2.73 $ 1.10 ------------------------------------------------------------------------------------------------------------------------------------ Distribution to shareowners: Net investment income $ -- $ -- $ -- $ -- $ -- $ (0.01) Net realized gain -- (0.37) (0.78) (0.47) (0.62) (0.11) ------------------------------------------------------------------------------------------------------------------------------------ Total distributions $ -- $ (0.37) $ (0.78) $ (0.47) $ (0.62) $ (0.12) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ 1.59 $ 1.54 $ (0.18) $ 2.15 $ 2.11 $ 0.98 ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 20.76 $ 19.17 $ 17.63 $ 17.81 $ 15.66 $ 13.55 ==================================================================================================================================== Total return* 8.29% 10.98% 3.29% 16.81% 20.29% 8.77% Ratio of net expenses to average net assets 1.75%** 1.77% 1.77% 1.79% 1.83% 1.91% Ratio of net investment income (loss) to average net assets (0.42)%** (0.30)% (0.29)% (0.32)% (0.28)% (0.23)% Portfolio turnover rate 30%** 23% 13% 12% 21% 28.00% Net assets, end of period (in thousands) $472,611 $465,545 $356,675 $246,593 $174,565 $89,299 ==================================================================================================================================== * Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions, the complete redemption of the investment at net asset value at the end of each period and no sales charges. Total return would be reduced if sales charges were taken into account. ** Annualized. (a) The amount shown for a share outstanding does not correspond with net investment income on the Statement of Operations for the period due to timing of the sales and repurchase of shares. (b) The per-share data presented above is based on the average shares outstanding for the period presented. The accompanying notes are an integral part of these financial statements. Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 29 Financial Highlights (continued) ------------------------------------------------------------------------------------------------------------------------------------ Six Months Ended Year Year Year Year 9/30/17 Ended Ended Ended Ended 12/20/12 to (unaudited) 3/31/17 3/31/16 3/31/15 3/31/14 3/31/13 ------------------------------------------------------------------------------------------------------------------------------------ Class K Net asset value, beginning of period $ 20.79 $ 19.00 $ 19.05 $ 16.64 $ 14.30 $ 13.37 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ 0.07(c) $ 0.16(c) $ 0.15(c) $ 0.16 $ 0.06 $ 0.03 Net realized and unrealized gain (loss) on investments 1.78 2.13 0.70 2.84 3.01 1.00 ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $ 1.85 $ 2.29 $ 0.85 $ 3.00 $ 3.07 $ 1.03 ------------------------------------------------------------------------------------------------------------------------------------ Distribution to shareowners: Net investment income $ -- $ (0.13) $ (0.12) $ (0.12) $ (0.11) $ (0.10) Net realized gain -- (0.37) (0.78) (0.47) (0.62) -- ------------------------------------------------------------------------------------------------------------------------------------ Total distributions $ -- $ (0.50) $ (0.90) $ (0.59) $ (0.73) $ (0.10) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ 1.85 $ 1.79 $ (0.05) $ 2.41 $ 2.34 $ 0.93 ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 22.64 $ 20.79 $ 19.00 $ 19.05 $ 16.64 $ 14.30 ==================================================================================================================================== Total return* 8.90% 12.24% 4.43% 18.11% 21.61% 7.77%(a)(b) Ratio of net expenses to average net assets 0.66%** 0.67% 0.67% 0.69% 0.71% 0.77%** Ratio of net investment income (loss) to average net assets 0.68%** 0.81% 0.80% 0.81% 0.85% 0.77%** Portfolio turnover rate 30%** 23% 13% 12% 21% 28% Net assets, end of period (in thousands) $ 515,565 $376,708 $131,813 $97,063 $31,501 $ 11 ==================================================================================================================================== * Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions and the complete redemption of the investment at net asset value at the end of each period. ** Annualized. (a) If the Fund had not recognized gains in settlement of class action lawsuits during the year ended March 31, 2013, the total return would have been 7.74%. (b) Not annualized. (c) The per-share data presented above is based on the average shares outstanding for the period presented. The accompanying notes are an integral part of these financial statements. 30 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 ------------------------------------------------------------------------------------------------------------------------------------ Six Months Ended Year Year Year Year 9/30/17 Ended Ended Ended Ended 4/2/12 to (unaudited) 3/31/17 3/31/16 3/31/15 3/31/14 3/31/13 ------------------------------------------------------------------------------------------------------------------------------------ Class R Net asset value, beginning of period $ 20.49 $ 18.76 $ 18.86 $ 16.50 $ 14.25 $ 13.34 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ (0.01)(d)(e) $ 0.01(d) $ 0.02(d) $ (0.00)(c) $ 0.01 $ 0.06 Net realized and unrealized gain (loss) on investments 1.75 2.10 0.69 2.83 2.94 1.05 ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $ 1.74 $ 2.11 $ 0.71 $ 2.83 $ 2.95 $ 1.11 ------------------------------------------------------------------------------------------------------------------------------------ Distribution to shareowners: Net investment income $ -- $ (0.01) $ (0.03) $ -- $ (0.08) $ (0.09) Net realized gain -- (0.37) (0.78) (0.47) (0.62) (0.11) ------------------------------------------------------------------------------------------------------------------------------------ Total distributions $ -- $ (0.38) $ (0.81) $ (0.47) $ (0.70) $ (0.20) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ 1.74 $ 1.73 $ (0.10) $ 2.36 $ 2.25 $ 0.91 ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 22.23 $ 20.49 $ 18.76 $ 18.86 $ 16.50 $ 14.25 ==================================================================================================================================== Total return* 8.49% 11.41% 3.70% 17.23% 20.84% 8.42%(a)(b) Ratio of net expenses to average net assets 1.39%** 1.40% 1.40% 1.40% 1.39% 1.40%** Ratio of net investment income (loss) to average net assets (0.05)%**(e) 0.08% 0.10% 0.05% 0.18% 0.27%** Portfolio turnover rate 30%** 23% 13% 12% 21% 28% Net assets, end of period (in thousands) $ 149,976 $117,931 $79,519 $ 37,285 $40,703 $ 2,437 Ratios with no waiver of fees and assumption of expenses by the Adviser and no reduction for fees paid indirectly: Total expenses to average net assets 1.39%** 1.41% 1.43% 1.52% 1.39% 1.45%** Net investment income (loss) to average net assets (0.05)%**(e) 0.07% 0.07% (0.07)% 0.18% 0.21%** ==================================================================================================================================== * Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions and the complete redemption of the investment at net asset value at the end of each period. ** Annualized. (a) If the Fund had not recognized gains in settlement of class action lawsuits during the year ended March 31, 2013, the total return would have been 8.41%. (b) Not annualized. (c) Amount rounds to less than $0.01 or $(0.01) per share. (d) The per-share data presented above is based on the average shares outstanding for the period presented. (e) The amount shown for a share outstanding does not correspond with net investment income on the Statement of Operations for the period due to timing of the sales and repurchase of shares. The accompanying notes are an integral part of these financial statements. Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 31 Financial Highlights (continued) ------------------------------------------------------------------------------------------------------------------------------------ Six Months Ended Year Year Year Year Year 9/30/17 Ended Ended Ended Ended Ended (unaudited) 3/31/17 3/31/16 3/31/15 3/31/14 3/31/13 ------------------------------------------------------------------------------------------------------------------------------------ Class Y Net asset value, beginning of period $ 20.95 $ 19.15 $ 19.20 $ 16.77 $ 14.41 $ 13.30 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ 0.06(b) $ 0.14(b) $ 0.13(b) $ 0.10 $ 0.10 $ 0.10 Net realized and unrealized gain (loss) on investments 1.79 2.14 0.71 2.90 2.97 1.22 ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $ 1.85 $ 2.28 $ 0.84 $ 3.00 $ 3.07 $ 1.32 ------------------------------------------------------------------------------------------------------------------------------------ Distribution to shareowners: Net investment income $ -- $ (0.11) $ (0.11) $ (0.10) $ (0.09) $ (0.10) Net realized gain -- (0.37) (0.78) (0.47) (0.62) (0.11) ------------------------------------------------------------------------------------------------------------------------------------ Total distributions $ -- $ (0.48) $ (0.89) $ (0.57) $ (0.71) $ (0.21) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ 1.85 $ 1.80 $ (0.05) $ 2.43 $ 2.36 $ 1.11 ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 22.80 $ 20.95 $ 19.15 $ 19.20 $ 16.77 $ 14.41 ==================================================================================================================================== Total return* 8.83% 12.11% 4.29% 17.98% 21.44% 9.99%(a) Ratio of net expenses to average net assets 0.78%** 0.77% 0.79% 0.80% 0.82% 0.81% Ratio of net investment income (loss) to average net assets 0.56%** 0.71% 0.70% 0.68% 0.72% 0.85% Portfolio turnover rate 30%** 23% 13% 12% 21% 28% Net assets, end of period (in thousands) $3,721,757 $3,198,861 $2,001,002 $1,263,594 $842,680 $558,383 ==================================================================================================================================== * Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions and the complete redemption of the investment at net asset value at the end of each period. ** Annualized. (a) If the Fund had not recognized gains in settlement of class action lawsuits during the year ended March 31, 2013, the total return would have been 9.96%. (b) The per-share data presented above is based on the average shares outstanding for the period presented. The accompanying notes are an integral part of these financial statements. 32 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 Notes to Financial Statements | 9/30/17 (unaudited) 1. Organization and Significant Accounting Policies Pioneer Fundamental Growth Fund (the Fund) is a series of Pioneer Series Trust X, a Delaware statutory trust. The Fund is registered under the Investment Company Act of 1940 as a diversified, open-end management investment company. The Fund's investment objective is to seek long-term capital growth. The Fund offers five classes of shares designated as Class A, Class C, Class K, Class R and Class Y shares. Each class of shares represents an interest in the same portfolio of investments of the Fund and has identical rights (based on relative net asset values) to assets and liquidation proceeds. Share classes can bear different rates of class-specific fees and expenses such as transfer agent and distribution fees. Differences in class-specific fees and expenses will result in differences in net investment income and, therefore, the payment of different dividends from net investment income earned by each class. The Amended and Restated Declaration of Trust of the Fund gives the Board of Trustees the flexibility to specify either per share voting or dollar-weighted voting when submitting matters for shareholder approval. Under per share voting, each share of a class of the Fund is entitled to one vote. Under dollar-weighted voting, a shareholder's voting power is determined not by the number of shares owned, but by the dollar value of the shares on the record date. Each share class has exclusive voting rights with respect to matters affecting only that class, including with respect to the distribution plan for that class. There is no distribution plan for Class K or Class Y shares. On July 3, 2017, Amundi acquired Pioneer Investments, a group of asset management companies located throughout the world. Amundi, one of the world's largest asset managers, is headquartered in Paris, France. As a result of the transaction, Pioneer Investment Management, Inc., the Funds' investment adviser, became an indirect wholly owned subsidiary of Amundi and Amundi's wholly owned subsidiary, Amundi USA, Inc. Prior to July 3, 2017, Pioneer Investments was owned by Pioneer Global Asset Management S.p.A., a wholly owned subsidiary of UniCredit S.p.A. In connection with the transaction, the names of the Funds' investment adviser and principal underwriter changed. Effective July 3, 2017, the name of Pioneer Investment Management, Inc. changed to Amundi Pioneer Asset Management, Inc. (the Adviser) and the name of Pioneer Funds Distributor, Inc. changed to Amundi Pioneer Distributor, Inc. (the Distributor). Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 33 In October 2016, the Securities and Exchange Commission (SEC) released its Final Rule on Investment Company Reporting Modernization. In addition to introducing two new regulatory reporting forms (Form N-PORT and Form N-CEN), the Final Rule amends Regulation S-X, which impacts financial statement presentation, particularly related to the presentation of derivative investments. The Fund's financial statements were prepared in compliance with the amendments to Regulation S-X. The Fund's financial statements have been prepared in conformity with U.S. generally accepted accounting principles (U.S. GAAP) that require the management of the Fund to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of income, expenses and gains and losses on investments during the reporting period. Actual results could differ from those estimates. The Fund is an investment company and follows investment company accounting and reporting guidance under U.S. GAAP. The following is a summary of significant accounting policies followed by the Fund in the preparation of its financial statements: A. Security Valuation The net asset value of the Fund is computed once daily, on each day the New York Stock Exchange (NYSE) is open, as of the close of regular trading on the NYSE. Equity securities that have traded on an exchange are valued by using the last sale price on the principal exchange where they are traded. Equity securities that have not traded on the date of valuation, or securities for which sale prices are not available, generally are valued using the mean between the last bid and asked prices or, if both last bid and asked prices are not available, at the last quoted bid price. Last sale and bid and asked prices are provided by independent third party pricing services. In the case of equity securities not traded on an exchange, prices are typically determined by independent third party pricing services using a variety of techniques and methods. The value of foreign securities is translated into U.S. dollars based on foreign currency exchange rate quotations supplied by a third party pricing source. Trading in non-U.S. equity securities is substantially completed each day at various times prior to the close of the NYSE. The values of such securities used in computing the net asset value of the Fund's shares are determined as of such times. The Fund may use a fair value model developed by an independent pricing service to value non-U.S. equity securities. 34 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 Fixed-income securities are valued by using prices supplied by independent pricing services, which consider such factors as market prices, market events, quotations from one or more brokers, Treasury spreads, yields, maturities and ratings, or may use a pricing matrix or other fair value methods or techniques to provide an estimated value of the security or instrument. A pricing matrix is a means of valuing a debt security on the basis of current market prices for other debt securities, historical trading patterns in the market for Fixed-income securities and/or other factors. Non-U.S. debt securities that are listed on an exchange will be valued at the bid price obtained from an independent third party pricing service. When independent third party pricing services are unable to supply prices, or when prices market quotations are considered to be unreliable, the value of that security may be determined using quotations from one or more broker-dealers. Securities for which independent pricing services or broker-dealers are unable to supply prices or for which market prices and/or quotations are not readily available or are considered to be unreliable are valued by a fair valuation team comprised of certain personnel of the Adviser pursuant to procedures adopted by the Fund's Board of Trustees. The Adviser's fair valuation team uses fair value methods approved by the Valuation Committee of the Board of Trustees. The Adviser's fair valuation team is responsible for monitoring developments that may impact fair valued securities and for discussing and assessing fair values on an ongoing basis, and at least quarterly, with the Valuation Committee of the Board of Trustees. Inputs used when applying fair value methods to value a security may include credit ratings, the financial condition of the company, current market conditions and comparable securities. The Fund may use fair value methods if it is determined that a significant event has occurred after the close of the exchange or market on which the security trades and prior to the determination of the Fund's net asset value. Examples of a significant event might include political or economic news, corporate restructurings, natural disasters, terrorist activity or trading halts. Thus, the valuation of the Fund's securities may differ significantly from exchange prices, and such differences could be material. At September 30, 2017, there were no securities that were valued using fair value methods (other than securities valued using prices supplied by independent pricing services). B. Investment Income and Transactions Dividend income is recorded on the ex-dividend date, except that certain dividends from foreign securities where the ex-dividend date may have passed are recorded as soon as the Fund becomes aware of the ex-dividend data in the exercise of reasonable diligence. Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 35 Interest income, including interest on income-bearing cash accounts, is recorded on the accrual basis. Dividend and interest income are reported net of unrecoverable foreign taxes withheld at the applicable country rates and net of income accrued on defaulted securities. Interest and dividend income payable by delivery of additional shares is reclassified as PIK (payment-in-kind) income upon receipt and is included in interest and dividend income, respectively. Security transactions are recorded as of trade date. Gains and losses on sales of investments are calculated on the identified cost method for both financial reporting and federal income tax purposes. C. Federal Income Taxes It is the Fund's policy to comply with the requirements of the Internal Revenue Code applicable to regulated investment companies and to distribute all of its net taxable income and net realized capital gains, if any, to its shareowners. Therefore, no provision for federal income taxes is required. As of March 31, 2017, the Fund did not accrue any interest or penalties with respect to uncertain tax positions, which, if applicable, would be recorded as an income tax expense in the Statement of Operations. Tax returns filed within the prior three years remain subject to examination by federal and state tax authorities. The amount and character of income and capital gain distributions to shareowners are determined in accordance with federal income tax rules, which may differ from U.S. GAAP. Distributions in excess of net investment income or net realized gains are temporary overdistributions for financial statement purposes resulting from differences in the recognition or classification of income or distributions for financial statement and tax purposes. Capital accounts within the financial statements are adjusted for permanent book/tax differences to reflect tax character, but are not adjusted for temporary differences. The tax character of current year distributions payable will be determined at the end of the fiscal year. The tax character of distributions during the year ended March 31, 2017 was as follows: --------------------------------------------------------------------------- 2017 --------------------------------------------------------------------------- Distributions paid from: Ordinary income $ 22,408,405 Long-term capital gain 90,517,680 --------------------------------------------------------------------------- Total $112,926,085 =========================================================================== 36 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 The following shows the components of distributable earnings on a federal income tax basis at March 31, 2017: --------------------------------------------------------------------------- 2017 --------------------------------------------------------------------------- Distributable earnings: Undistributed ordinary income $ 13,497,760 Undistributed long-term capital gain 55,326,435 Unrealized appreciation 1,094,857,369 --------------------------------------------------------------------------- Total $1,163,681,564 --------------------------------------------------------------------------- The difference between book-basis and tax-basis net unrealized appreciation is attributable to the tax deferral of losses on wash sales and tax basis adjustments on common stock. D. Fund Shares The Fund records sales and repurchases of its shares as of trade date. The Distributor earned $155,400 in underwriting commissions on the sale of Class A shares during the six months ended September 30, 2017. E. Class Allocations Income, common expenses and realized and unrealized gains and losses are calculated at the Fund level and allocated daily to each class of shares based on its respective percentage of adjusted net assets at the beginning of the day. Distribution fees are calculated based on the average daily net asset value attributable to Class A, Class C and Class R shares of the Fund, respectively (see Note 4). Class K and Class Y shares do not pay distribution fees. All expenses and fees paid to the Fund's transfer agent for its services are allocated among the classes of shares based on the number of accounts in each class and the ratable allocation of related out-of-pocket expenses (see Note 3). Distributions to shareowners are recorded as of the ex-dividend date. Distributions paid by the Fund with respect to each class of shares are calculated in the same manner and at the same time, except that net investment income dividends to Class A, Class C, Class K, Class R and Class Y shares can reflect different transfer agent and distribution expense rates. F. Risks The value of securities held by the fund may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic, political or regulatory conditions, inflation, changes in interest rates, lack of liquidity in the bond markets or adverse investor sentiment. In the past several years, financial markets have experienced increased volatility, depressed valuations, decreased liquidity and Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 37 heightened uncertainty. These conditions may continue, recur, worsen or spread. At times, the Fund's investments may represent industries or industry sectors that are interrelated or have common risks, making the Fund more susceptible to any economic, political, or regulatory developments or other risks affecting those industries and sectors. The Fund's prospectus contains unaudited information regarding the Fund's principal risks. Please refer to that document when considering the Fund's principal risks. G. Repurchase Agreements Repurchase agreements are arrangements under which the Fund purchases securities from a broker-dealer or a bank, called the counterparty, upon the agreement of the counterparty to repurchase the securities from the Fund at a later date, and at a specific price, which is typically higher than the purchase price paid by the Fund. The securities purchased serve as the Fund's collateral for the obligation of the counterparty to repurchase the securities. The value of the collateral, including accrued interest, is required to be equal to or in excess of the repurchase price. The collateral for all repurchase agreements is held in safekeeping in the customer-only account of the Fund's custodian or a subcustodian of the Fund. The Adviser is responsible for determining that the value of the collateral remains at least equal to the repurchase price. In the event of a default by the counterparty, the Fund is entitled to sell the securities, but the Fund may not be able to sell them for the price at which they were purchased, thus causing a loss to the Fund. Additionally, if the counterparty becomes insolvent, there is some risk that the Fund will not have a right to the securities, or the immediate right to sell the securities. Open repurchase agreements at September 30, 2017 are listed at the end of the Schedule of Investments. 2. Management Agreement The Adviser manages the Fund's portfolio. Management fees are calculated daily at the annual rate of 0.65% of the Fund's average daily net assets up to $1 billion and 0.60% on assets over $1 billion. For the six months ended September 30, 2017, the effective management fee (excluding waivers and/or assumption of expenses) was equivalent to 0.61% of the Fund's average daily net assets. The Adviser has contractually agreed to limit ordinary operating expenses (ordinary operating expenses means all fund expenses other than extraordinary expenses, such as litigation, taxes, brokerage commissions and acquired fund fees and expenses) of the Fund to the extent required to reduce Fund expenses to 1.09%, 1.40% and 0.83% of the average daily net assets attributable to Class A, Class R, and Class Y shares, respectively. Class C and Class K shares do not have an expense limitation. Fees waived and expenses reimbursed during the six 38 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 months ended September 30, 2017 are reflected on the Statement of Operations. These expense limitations are in effect through August 1, 2019. There can be no assurance that the Adviser will extend the expense limitation agreement for a class of shares beyond the date referred to above. In addition, under the management and administration agreements, certain other services and costs, including accounting, regulatory reporting and insurance premiums, are paid by the Fund as administrative reimbursements. Included in "Due to affiliates" reflected on the Statement of Assets and Liabilities is $834,468 in management fees, administrative costs and certain other reimbursements payable to the Adviser at September 30, 2017. 3. Transfer Agent Boston Financial Data Services, Inc. serves as the transfer agent to the Fund at negotiated rates. Transfer agent fees and payables shown on the Statement of Operations and the Statement of Assets and Liabilities, respectively, include sub-transfer agent expenses incurred through the Fund's omnibus relationship contracts. In addition, the Fund reimbursed the transfer agent for out-of-pocket expenses incurred by the transfer agent related to shareholder communications activities such as proxy and statement mailings and outgoing phone calls. For the six months ended September 30, 2017, such out-of-pocket expenses by class of shares were as follows: -------------------------------------------------------------------------------- Shareholder Communications: -------------------------------------------------------------------------------- Class A $ 47,292 Class C 26,413 Class K 3,730 Class R 1,963 Class Y 66,354 -------------------------------------------------------------------------------- Total $145,752 ================================================================================ 4. Distribution and Service Plans The Fund has adopted a distribution plan pursuant to Rule 12b-1 of the Investment Company Act of 1940 with respect to its Class A, Class C and Class R shares (the Plan). Pursuant to the Plan, the Fund pays the Distributor 0.25% of the average daily net assets attributable to Class A shares as compensation for personal services and/or account maintenance services or distribution services with regard to Class A shares. Pursuant to the Plan, the Fund also pays the Distributor 1.00% of the average daily net assets attributable to Class C shares. The fee for Class C shares consists of a 0.25% service fee and a 0.75% distribution fee paid as compensation for personal Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 39 services and/or account maintenance services or distribution services with regard to Class C shares. Pursuant to the Plan, the Fund further pays the Distributor 0.50% of the average daily net assets attributable to Class R shares for distribution services. Included in "Due to affiliates" reflected on the Statement of Assets and Liabilities is $188,001 in distribution fees payable to the Distributor at September 30, 2017. The Fund also has adopted a separate service plan for Class R shares (Service Plan). The Service Plan authorizes the Fund to pay securities dealers, plan administrators or other service organizations that agree to provide certain services to retirement plans or plan participants holding shares of the Fund a service fee of up to 0.25% of the Fund's average daily net assets attributable to Class R shares held by such plans. In addition, redemptions of each class of shares (except Class K, Class R and Class Y shares) may be subject to a contingent deferred sales charge (CDSC). A CDSC of 1.00% may be imposed on redemptions of certain net asset value purchases of Class A shares within 12 months of purchase. Redemptions of Class C shares within 12 months of purchase are subject to a CDSC of 1.00%, based on the lower of cost or market value of shares being redeemed. Shares purchased as part of an exchange remain subject to any CDSC that applied to the original purchase of those shares. There is no CDSC for Class K, Class R or Class Y shares. Proceeds from the CDSCs are paid to the Distributor. For the six months ended September 30, 2017, CDSCs in the amount of $79,270 were paid to the Distributor. 5. Line of Credit Facility The Fund, along with certain other funds in the Pioneer Family of Funds (the Funds), participates in a committed, unsecured revolving line of credit facility. Borrowings are used solely for temporary or emergency purposes. The Fund may borrow up to the lesser of the amount available under the facility or the limits set for borrowing by the Fund's prospectus and the 1940 Act. The credit facility in which the Fund participated until February 9, 2016 was in the amount of $240 million. The credit facility in which the fund participated until February 7, 2017 was in the amount of $220 million. Effective February 8, 2017, the Fund participates in a facility that is in the amount of $195 million. Under such facility, depending on the type of loan, interest on borrowings is payable at the London Interbank Offered Rate (LIBOR) plus 0.85% on an annualized basis, or the Alternate Base Rate, which is the greater of (a) the facility's administrative agent's daily announced prime rate on the borrowing date, (b) 2% plus the Federal Funds Rate on the borrowing date or (c) 2% plus the overnight Eurodollar rate on the borrowing date. The Funds pay an annual commitment fee to participate in a credit facility. The commitment fee is 40 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 allocated among participating Funds based on an allocation schedule set forth in the credit agreement. For the six months ended September 30, 2017, the Fund had no borrowings under the credit facility. 6. Shareholder Meeting Results At a special meeting held on June 13, 2017, shareholders of the Fund were asked to consider the proposals described below. A report of the total votes cast by the Fund's shareholders (or, with respect to Proposal 2, by shareholders of Pioneer Series Trust X, as noted below) follows: --------------------------------------------------------------------------------------------------- For Against Abstain Broker Non-Votes --------------------------------------------------------------------------------------------------- Proposal 1 - To approve 95,986,541.168 1,771,972.782 2,863,460.674 34,672,082.955 a New Management Agreement with the Adviser --------------------------------------------------------------------------------------------------- For Withhold --------------------------------------------------------------------------------------------------- Proposal 2 - To elect Trustees* --------------------------------------------------------------------------------------------------- David R. Bock 343,352,480.124 5,326,068.613 --------------------------------------------------------------------------------------------------- Benjamin M. Friedman 343,252,747.228 5,425,801.509 --------------------------------------------------------------------------------------------------- Margaret B.W. Graham 343,431,726.450 5,246,822.287 --------------------------------------------------------------------------------------------------- Lisa M. Jones 343,414,583.887 5,263,964.850 --------------------------------------------------------------------------------------------------- Lorraine H. Monchak 339,444,451.562 9,234,097.175 --------------------------------------------------------------------------------------------------- Thomas J. Perna 343,393,493.010 5,285,055.727 --------------------------------------------------------------------------------------------------- Marguerite A. Piret 343,442,072.938 5,236,475.799 --------------------------------------------------------------------------------------------------- Fred J. Ricciardi 343,367,033.730 5,311,515.007 --------------------------------------------------------------------------------------------------- Kenneth J. Taubes 343,361,588.526 5,316,960.211 --------------------------------------------------------------------------------------------------- * Proposal 2 was voted on and approved by all series of Pioneer Series Trust X. Results reported above reflect the combined votes of all series of the Trust. Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 41 Additional Information Change in Independent Registered Public Accounting Firm Prior to July 3, 2017, Pioneer Investment Management, Inc. (the "Adviser"), the Fund's investment adviser, was an indirect, wholly owned subsidiary of UniCredit S.p.A. ("UniCredit"). On that date, UniCredit completed the sale of its Pioneer Investments business, which includes the Adviser, to Amundi (the "Transaction"). As a result of the Transaction, the Adviser became an indirect, wholly-owned subsidiary of Amundi. Amundi is controlled by Credit Agricole S.A. Amundi is headquartered in Paris, France, and, as of September 30, 2016, had more than $1.1 trillion in assets under management worldwide. Deloitte & Touche LLP ("D&T"), the Fund's previous independent registered public accounting firm, informed the Audit Committee and the Board that it would no longer be independent with respect to the Fund upon the completion of the Transaction as a result of certain services being provided to Amundi and Credit Agricole, and, accordingly, that it intended to resign as the Fund's independent registered public accounting firm upon the completion of the Transaction. D&T's resignation was effective on July 3, 2017, when the Transaction was completed. During the periods as to which D&T has served as the Fund's independent registered public accounting firm, including the Fund's two most recent fiscal years preceding the fiscal year ended March 31, 2017, D&T's reports on the Fund's financial statements have not contained an adverse opinion or disclaimer of opinion and have not been qualified or modified as to uncertainty, audit scope or accounting principles. Further, there have been no disagreements with D&T on any matter of accounting principles or practices, financial statement disclosure, or auditing scope or procedure, which, if not resolved to the satisfaction of D&T, would have caused D&T to make reference to the subject matter of the disagreement in connection with its report on the financial statements. In addition, there have been no reportable events of the kind described in Item 304(a)(1)(v) of Regulation S-K under the Securities Exchange Act of 1934. Effective immediately following the completion of the Transaction on July 3, 2017, the Board, acting upon the recommendation of the Audit Committee, engaged a new independent registered public accounting firm, Ernst & Young LLP ("EY"), for the Fund's fiscal year ended March 31, 2018. 42 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 Prior to its engagement, EY had advised the Fund's Audit Committee that EY had identified the following matters, in each case relating to services rendered by other member firms of Ernst & Young Global Limited, all of which are located outside the United States, to UniCredit and certain of its subsidiaries during the period commencing July 1, 2016, that it determined to be inconsistent with the auditor independence rules set forth by the Securities and Exchange Commission ("SEC"): (a) project management support services to UniCredit in the Czech Republic, Germany, Italy, Serbia and Slovenia in relation to twenty-two projects, that were determined to be inconsistent with Rule 2-01(c)(4)(vi) of Regulation S-X (management functions); (b) two engagements for UniCredit in Italy where fees were contingent/success based and that were determined to be inconsistent with Rule 2-01(c)(5) of Regulation S-X (contingent fees); (c) four engagements where legal and expert services were provided to UniCredit in the Czech Republic and Germany, and twenty engagements where the legal advisory services were provided to UniCredit in Austria, Czech Republic, Italy and Poland, that were determined to be inconsistent with Rule 2-01(c)(4)(ix) and (x) of Regulation S-X (legal and expert services); and (d) two engagements for UniCredit in Italy involving assistance in the sale of certain assets, that were determined to be inconsistent with Rule 2-01(c)(4)(viii) of Regulation S-X (broker-dealer, investment advisor or investment banking services). None of the foregoing services involved the Fund, any of the other funds in the Pioneer Family of Funds or any other Pioneer entity sold by UniCredit in the Transaction. EY advised the Audit Committee that it had considered the matters described above and had concluded that such matters would not impair EY's ability to exercise objective and impartial judgment in connection with the audits of the financial statements of the Fund under the SEC and Public Company Accounting Oversight Board independence rules, and that a reasonable investor with knowledge of all relevant facts and circumstances would reach the same conclusion. Management and the Audit Committee considered these matters and discussed the matters with EY and, based upon EY's description of the matters and statements made by EY, Management and the Audit Committee believe that EY will be capable of exercising objective and impartial judgment in connection with the audits of the financial statements of the Fund, and Management further believes that a reasonable investor with knowledge of all relevant facts and circumstances would reach the same conclusion. Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 43 Trustees, Officers and Service Providers Trustees Officers Thomas J. Perna, Chairman Lisa M. Jones, President and Chief David R. Bock Executive Officer Benjamin M. Friedman Mark E. Bradley, Treasurer and Margaret B.W. Graham Chief Financial Officer Lisa M. Jones Christopher J. Kelley, Secretary and Lorraine H. Monchak Chief Legal Officer Marguerite A. Piret Fred J. Ricciardi Kenneth J. Taubes Investment Adviser and Administrator Amundi Pioneer Asset Management, Inc. Custodian and Sub-Administrator Brown Brothers Harriman & Co. Principal Underwriter Amundi Pioneer Distributor, Inc. Legal Counsel Morgan, Lewis & Bockius LLP Shareowner Services and Transfer Agent Boston Financial Data Services, Inc. Proxy Voting Policies and Procedures of the Fund are available without charge, upon request, by calling our toll free number (1-800-225-6292). Information regarding how the Fund voted proxies relating to portfolio securities during the most recent 12-month period ended June 30 is publicly available to shareowners at www.amundipioneer.com. This information is also available on the Securities and Exchange Commission's web site at www.sec.gov. 44 Pioneer Fundamental Growth Fund | Semiannual Report | 9/30/17 How to Contact Amundi Pioneer We are pleased to offer a variety of convenient ways for you to contact us for assistance or information. Call us for: -------------------------------------------------------------------------------- Account Information, including existing accounts, new accounts, prospectuses, applications and service forms 1-800-225-6292 FactFone(SM) for automated fund yields, prices, account information and transactions 1-800-225-4321 Retirement plans information 1-800-622-0176 Write to us: -------------------------------------------------------------------------------- Amundi Pioneer P.O. Box 55014 Boston, Massachusetts 02205-5014 Our toll-free fax 1-800-225-4240 Our internet e-mail address ask.amundipioneer@amundipioneer.com (for general questions about Amundi Pioneer only) Visit our web site: www.amundipioneer.com This report must be preceded or accompanied by a prospectus. The Fund files a complete schedule of investments with the Securities and Exchange Commission for the first and third quarters for each fiscal year on Form N-Q. Shareholders may view the filed Form N-Q by visiting the Commission's web site at http://www.sec.gov. The filed form may also be viewed and copied at the Commission's Public Reference Room in Washington, DC. Information regarding the operations of the Public Reference Room may be obtained by calling 1-800-SEC-0330. [LOGO] Amundi Pioneer ============== ASSET MANAGEMENT Amundi Pioneer Asset Management, Inc. 60 State Street Boston, MA 02109 www.amundipioneer.com Securities offered through Amundi Pioneer Funds Distributor, Inc. 60 State Street, Boston, MA 02109 Underwriter of Pioneer Mutual Funds, Member SIPC (C) 2017 Amundi Pioneer Asset Management 19434-11-1117 Pioneer Multi-Asset Ultrashort Income Fund -------------------------------------------------------------------------------- Semiannual Report | September 30, 2017 -------------------------------------------------------------------------------- Ticker Symbols: Class A MAFRX Class C MCFRX Class C2 MAUCX Class K MAUKX Class Y MYFRX [LOGO] Amundi Pioneer ============== ASSET MANAGEMENT visit us: www.amundipioneer.com Table of Contents President's Letter 2 Portfolio Management Discussion 4 Portfolio Summary 10 Prices and Distributions 11 Performance Update 12 Comparing Ongoing Fund Expenses 17 Schedule of Investments 19 Financial Statements 101 Notes to Financial Statements 110 Additional Information 121 Trustees, Officers and Service Providers 123 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 1 President's Letter Robust, synchronized global economic growth and rising corporate profits have continued to drive strong performance in both the credit and equity markets for most of 2017. U.S. stocks, as measured by the Standard & Poor's 500 Index, have returned 14.23% year-to-date through September 30, 2017. Fixed-income markets, while not generating the same dazzling returns as equities, have held their own, led by high-yield securities, which produced a year-to-date return of 7.05% in the U.S., as measured by the Bank of America Merrill Lynch U.S. High Yield Index. Meanwhile, the Bloomberg Barclays U.S. Aggregate Bond Index has returned 3.14% since the start of the calendar year. Continued strong employment numbers and higher consumer confidence, together with solid global economic growth and a depreciating U.S. dollar contributed to better-than-expected U.S. gross domestic product (GDP) growth of 3.1% in the second quarter. Outside the U.S., economic growth in the second quarter also surprised to the upside across the Euro zone, China, and Japan. Meanwhile, despite higher oil and commodities prices, inflation continued to be moderate, both in the U.S. and globally, enabling major non-U.S. central banks to maintain their easy monetary policies. As expected, however, the U.S. Federal Reserve System (the Fed) recently announced that it would commence tapering its balance sheet this October. The Fed also appears primed to raise interest rates one more time before the end of this year, which would be the fourth rate increase since December of 2016. As we move into the final months of 2017, we believe the U.S. economy will experience modest growth in the short term, depending on the mix of economic policies enacted as the country moves away from monetary stimulus (driven by the Fed) and toward fiscal stimulus (potentially including tax reform) as well as lighter regulatory burdens. Meanwhile, corporate earnings remain solid and we think they will improve even further, despite some pressure from wage increases. In addition, as the economy continues to grow and we begin to see a modest upturn in inflation, we believe the Fed will continue to raise interest rates. While economic and market conditions appear solid, there are always risks to consider that could dampen the outlook. Geopolitical concerns, such as increased tensions with North Korea, and continued political gridlock in Washington are just some of the risks that could lead to increased market volatility. 2 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 It is for those reasons that we at Amundi Pioneer continue to believe that investors can benefit from the experience and tenure of our investment teams who make active and informed decisions across our funds. As always, and particularly during times of market uncertainty, we encourage you to work with your financial advisor to develop an overall investment plan that addresses both your short- and long-term goals, and to implement such a plan in a disciplined manner. We greatly appreciate the trust you have placed in us and look forward to continuing to serve you in the future. Sincerely, /s/ Lisa M. Jones Lisa M. Jones Head of the Americas, President and CEO of U.S. Amundi Pioneer Asset Management USA, Inc. September 30, 2017 Any information in this shareowner report regarding market or economic trends or the factors influencing the Fund's historical or future performance are statements of opinion as of the date of this report. Past performance is no guarantee of future results. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 3 Portfolio Management Discussion | 9/30/17 In the following interview, portfolio managers Charles Melchreit, Seth Roman, and Jonathan Sharkey discuss the factors that influenced the performance of Pioneer Multi-Asset Ultrashort Income Fund during the six-month period ended September 30, 2017. Mr. Melchreit, Deputy Head of Fixed Income, U.S., Director of Multi-Sector Fixed Income, a senior vice president, and a portfolio manager at Amundi Pioneer Asset Management, Inc. ("Amundi Pioneer"); Mr. Roman, a vice president and a portfolio manager at Amundi Pioneer; and Mr. Sharkey, a senior vice president and a portfolio manager at Amundi Pioneer, are responsible for the day-to-day management of the Fund. Q How did the Fund perform during the six-month period ended September 30, 2017? A Pioneer Multi-Asset Ultrashort Income Fund's Class A shares returned 0.78% at net asset value (NAV) during the six-month period ended September 30, 2017, while the Fund's benchmark, the Bank of America Merrill Lynch 3-Month U.S. Dollar LIBOR Index (the BofA ML Index), returned 0.59%. During the same period, the average return of the 139 mutual funds in Lipper's Ultrashort Obligations Funds category was 0.68%, and the average return of the 178 mutual funds in Morningstar's Ultrashort Bond category was 0.74%. Q How would you describe the market environment for fixed-income investors over the six-month period ended September 30, 2017? A During the period, investor sentiment with respect to credit-oriented areas of the bond market continued to receive support from generally positive economic data. Despite indications that inflation was running below its 2% target, the Federal Reserve (the Fed) implemented its second rate hike of the year in June, increasing the federal funds target range by 25 basis points (bps), or 0.25%, to between 1.00% and 1.25%. With few signs of inflationary pressure despite improvements in the labor market, the Fed remained on hold over the rest of the period with respect to its benchmark short-term lending rate. However, in September the Fed announced plans to begin gradually reducing its balance sheet in October by shedding some of the securities it had purchased during its multiple quantitative-easing programs between 2008 and 2014. The market had long anticipated the Fed's tapering plans, however, and so the announcement of a concrete timeframe for its commencement generated a muted reaction. 4 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 The U.S. Treasury curve flattened over the six-month period, as short-term yields rose while yields declined on Treasuries with longer maturities. To illustrate, the two-year Treasury yield rose from 1.27% to 1.47% during the period, the five-year Treasury yield went from 1.93% to 1.92%, and the 10-year Treasury yield dropped from 2.40% to 2.33%. Over the same period, the three-month London Interbank Offered Rate (LIBOR), a commonly used baseline for loans and securities, rose from 1.15% to 1.36%. In addition, credit spreads generally narrowed over the six months. (Credit spreads are commonly defined as the differences in yield between Treasuries and other types of fixed-income securities with similar maturities.) Q Can you review your principal strategies in managing the Fund during the six-month period ended September 30, 2017, and their effects on performance? A During the period, we continued to maintain a portfolio of investments that seeks to provide income, while also striving to protect shareholders' principal against a rise in market interest rates. Our strategy entailed investing the portfolio in a wide range of mostly high-quality floating-rate securities as well as fixed-rate instruments with very short remaining maturities. At period end, well over 90% of the Fund's total investment portfolio was allocated either to floating-rate issues with interest rates tied to a short-term reference rate, such as LIBOR, or to fixed-rate issues with less than one-year duration. (Duration is a measure of the sensitivity of the price, or the value of principal, of a fixed-income investment to a change in interest rates, expressed as a number of years.) Unlike many other floating-rate vehicles, we typically invest the Fund's assets with a primary focus on investment-grade asset classes. At the same time, we did seek to have the Fund's performance benefit from credit spreads during the period. In doing so, we sought at all times to maintain the portfolio's broadly diversified* exposure to a number of different spread sectors. (Spread sectors represent non-governmental fixed-income investments with higher yields - at greater risk - than governmental investments.) The portfolio's allocations to credit-sensitive areas of the fixed-income market supported the Fund's outperformance relative to the BofA ML Index during the six-month period. The leading contributor to the Fund's relative returns was an allocation to securitized assets, such as asset-backed securities (ABS), commercial mortgage-backed securities (CMBS), and * Diversification does not assure a profit nor protect against loss. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 5 collateralized mortgage obligations (CMOs). Within that allocation, the biggest contributions came from the Fund's highly diversified ABS position, as the asset class continued to benefit from improvements in both the U.S. employment backdrop and consumer balance sheets. The Fund's allocation to investment-grade corporate bonds also aided benchmark-relative performance during the period. Within investment-grade corporates, the Fund has a heavy tilt toward financial issues, most notably U.S. banks, with diversified holdings across both money center and regional banks. We view those issuers as attractive, due in part to the more stringent regulations concerning the use of leverage that has been applied to the domestic banking sector since the financial crisis. The Fund also has modest exposure to banks in Japan as well as select European markets. While our investment focus for the Fund is on the investment-grade sectors, we also include below-investment-grade asset categories in the portfolio, in areas where we believe the incremental income available provides an attractive tradeoff between risk and reward. In that vein, the Fund's modest position in leveraged bank loans made a small positive contribution to relative performance during the period as credit spreads narrowed. We have a cautious stance with respect to the loan market overall, as many higher-rated loans currently trade above par (face) value without call protection. On the negative side, the Fund's position in insurance-linked securities, including so-called "catastrophe" bonds, which are issued by insurance companies looking to offload some of the risk of having to pay claims after a natural disaster, slightly detracted from benchmark-relative returns. Catastrophe ("cat") bonds traded lower towards the end of the period in the wake of Hurricanes Harvey and Irma making landfall. We like to maintain an allocation to cat bonds in the portfolio, given the incremental income they provide as well as their very low correlation to other securities markets. (Correlation represents the degree to which assets or asset class prices have moved in relation to one another. Correlation ranges from -1, where assets/asset prices always move in opposite directions, through 0, where assets/asset prices are absolutely independent, to 1, where assets/asset prices always move together.) Despite the recent underperformance, we anticipate that yields on new insurance-linked bond issues in coming years will be attractive relative to recent history, as insurers seek to mitigate payment risk further after 2017's severe hurricane season. While we manage the Fund with a focus on total return, we are mindful that many investors also view the Fund as a source of liquidity in their portfolios. As such, we make sure to maintain significant portfolio liquidity in an effort to help reduce fluctuations in the Fund's NAV. 6 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 Q Can you discuss the factors that affected the Fund's income-generation (or yield), from either a positive or negative standpoint during the six-month period ended September 30, 2017? A As we noted earlier, throughout the period, floating-rate issues with interest rates tied to LIBOR or other short-term reference rates made up the bulk of the Fund's total investment portfolio. The Fund's income benefited from that positioning over the six months as short-term LIBOR rates rose in anticipation of the Fed's increasing its overnight lending rate at least one more time in 2017. Q Did you use any derivative strategies in managing the Fund during the six-month period ended September 30, 2017? A No, we did not utilize derivatives in managing the Fund during the period. Q What is your assessment of the current investment climate for the Fund, and how have you positioned the Fund's portfolio based on that view? A We believe that conditions remain supportive of fundamentals in the credit-sensitive sectors of the market, as reflected in strong corporate earnings and low unemployment. While the outlook for progress on the Trump administration's pro-growth fiscal agenda remains clouded, sentiment in the spread sectors would receive further support should tax reform become a reality. The Fed appears poised to raise rates again as soon as December, but we do not anticipate an acceleration in the pace of rate hikes that would unsettle credit markets. Increases in the federal funds rate would put upward pressure on LIBOR and therefore help the Fund's income generation. Credit spreads, meanwhile, are generally the tightest they have been at any point since the financial crisis of 2008. As always, we are taking care not to assume any risk for which the Fund is not seeking adequate compensation. In that vein, we are being careful not to reach for yield, and are maintaining the portfolio's spread duration, or sensitivity to changes in credit spreads, at current levels. We also continue to emphasize significant liquidity within the portfolio. While the portfolio's sector allocations will shift around the margins to reflect our view of relative risk and reward, we continue to diversify Fund's portfolio broadly with respect to its allocation across asset categories. In all investment environments, however, we will continue to seek to provide shareholders with higher income than cash vehicles, albeit with additional risk, while striving to provide protection against any future rise in market interest rates. (Please note that the Fund is not a money market fund.) Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 7 Please refer to the Schedule of Investments on pages 19-100 for a full listing of Fund securities. All investments are subject to risk, including the possible loss of principal. In the past several years, financial markets have experienced increased volatility, depressed valuations, decreased liquidity and heightened uncertainty. These conditions may continue, recur, worsen or spread. Pioneer Multi-Asset Ultrashort Income Fund ("The Fund") has the ability to invest in a wide variety of debt securities. The Fund may invest in underlying funds (including ETFs). In addition to the Fund's operating expenses, you will indirectly bear the operating expenses of investments in any underlying funds. The Fund and some of the underlying funds may utilize strategies that have a leveraging effect on the Fund, which increases the volatility of investment returns and subjects the Fund to magnified losses if the Fund's or an underlying fund's investments decline in value. The Fund and some of the underlying funds may use derivatives, such as options and futures, which can be illiquid, may disproportionately increase losses, and have a potentially large impact on Fund performance. The Fund may invest in inflation-linked securities. As inflationary expectations increase, inflation-linked securities may become more attractive, because they protect future interest payments against inflation. Conversely, as inflationary concerns decrease, inflation-linked securities will become less attractive and less valuable. The Fund may invest in credit default swaps, which may in some cases be illiquid, and they increase credit risk since the Fund has exposure to both the issuer of the referenced obligation and the counterparty to the credit default swap. The Fund may invest in subordinated securities which may be disproportionately adversely affected by a default or even a perceived decline in creditworthiness of the issuer. The Fund may invest in floating-rate loans. The value of collateral, if any, securing a floating-rate loan can decline or may be insufficient to meet the issuer's obligations or may be difficult to liquidate. The Fund may invest in event-linked bonds. The return of principal and the payment of interest on event-linked bonds are contingent on the non-occurrence of a pre-defined "trigger" event, such as a hurricane or an earthquake of a specific magnitude. The Fund may invest in zero-coupon bonds and payment-in-kind securities, which may be more speculative and fluctuate more in value than other fixed income securities. The accrual of income from these securities are payable as taxable annual dividends to shareholders. 8 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 Investments in equity securities are subject to price fluctuation. International investments are subject to special risks including currency fluctuations, social, economic and political uncertainties, which could increase volatility. These risks are magnified in emerging markets. Investments in fixed-income securities involve interest rate, credit, inflation, and reinvestment risks. As interest rates rise, the value of fixed income securities generally falls. The Fund may invest in mortgage-backed securities, which during times of fluctu- ating interest rates may increase or decrease more than other fixed-income securities. Mortgage-backed securities are also subject to pre-payments. Prepayment risk is the chance that an issuer may exercise its right to prepay its security, if falling interest rates prompt the issuer to do so. Forced to reinvest the unanticipated proceeds at lower interest rates, the Fund would experience a decline in income and lose the opportunity for additional price appreciation. High yield bonds possess greater price volatility, illiquidity, and possibility of default. There may be insufficient or illiquid collateral securing the floating rate loans held within the Fund. This may reduce the future redemption or recovery value of such loans. The Fund may have disadvantaged access to confidential information that could be used to assess a loan issuer, as Amundi Pioneer normally seeks to avoid receiving material, non-public information. Pioneer Multi-Asset Ultrashort Income Fund is not a money market fund. These risks may increase share price volatility. There is no assurance that these and other strategies used by the Fund or underlying funds will be successful. Please see the prospectus for a more complete discussion of the Fund's risks. Before investing, consider the product's investment objectives, risks, charges and expenses. Contact your advisor or Amundi Pioneer Asset Management, Inc., for a prospectus or summary prospectus containing this information. Read it carefully. Any information in this shareholder report regarding market or economic trends or the factors influencing the Fund's historical or future performance are statements of opinion as of the date of this report. Past performance is no guarantee of future results. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 9 Portfolio Summary | 9/30/17 Portfolio Diversification* -------------------------------------------------------------------------------- (As a percentage of total investment portfolio) [THE FOLLOWING DATA WAS REPRESENTED AS A PIE CHART IN THE PRINTED MATERIAL] Asset Backed Securities 28.9% Collateralized Mortgage Obligations 24.2% U.S. Corporate Bonds 20.3% U.S. Government Securities 9.5% International Corporate Bonds 7.4% Temporary Cash Investments 4.9% Senior Secured Loans 4.8% Municipal Bond 0.0%+ + Amount rounds to less than 0.1%. * Includes investments in Insurance Linked Securities totaling 3.9% of total investment portfolio. 10 Largest Holdings -------------------------------------------------------------------------------- (As a percentage of total long-term holdings)** 1. U.S. Treasury Note, Floating Rate Note, 10/31/17 1.29% -------------------------------------------------------------------------------- 2. U.S. Treasury Note, Floating Rate Note, 4/30/19 1.28 -------------------------------------------------------------------------------- 3. U.S. Treasury Note, Floating Rate Note, 1/31/19 1.27 -------------------------------------------------------------------------------- 4. U.S. Treasury Note, Floating Rate Note, 7/31/18 1.24 -------------------------------------------------------------------------------- 5. U.S. Treasury Note, Floating Rate Note, 10/31/18 1.24 -------------------------------------------------------------------------------- 6. U.S. Treasury Note, Floating Rate Note, 1/31/18 1.23 -------------------------------------------------------------------------------- 7. U.S. Treasury Note, Floating Rate Note, 4/30/18 1.22 -------------------------------------------------------------------------------- 8. U.S. Treasury Note, Floating Rate Note, 7/31/19 0.78 -------------------------------------------------------------------------------- 9. AbbVie, Inc., 1.8%, 5/14/18 0.36 -------------------------------------------------------------------------------- 10. Aetna, Inc., Floating Rate Note, 12/8/17 0.35 -------------------------------------------------------------------------------- ** This list excludes temporary cash investments. The portfolio is actively managed and current holdings may be different. The holdings listed should not be considered recommendations to buy or sell any security listed. 10 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 Prices and Distributions | 9/30/17 Net Asset Value per Share -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Class 9/30/17 3/31/17 -------------------------------------------------------------------------------- A $9.98 $9.99 -------------------------------------------------------------------------------- C $9.96 $9.97 -------------------------------------------------------------------------------- C2 $9.96 $9.97 -------------------------------------------------------------------------------- K $9.99 $9.99 -------------------------------------------------------------------------------- Y $9.98 $9.99 -------------------------------------------------------------------------------- Distributions per Share: 4/1/17-9/30/17 -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Short-Term Long-Term Class Dividends Capital Gains Capital Gains -------------------------------------------------------------------------------- A $0.0880 $ -- $ -- -------------------------------------------------------------------------------- C $0.0717 $ -- $ -- -------------------------------------------------------------------------------- C2 $0.0715 $ -- $ -- -------------------------------------------------------------------------------- K $0.0989 $ -- $ -- -------------------------------------------------------------------------------- Y $0.0948 $ -- $ -- -------------------------------------------------------------------------------- The Bank of America Merrill Lynch U.S. Dollar 3-Month LIBOR Index is an unmanaged index that tracks the performance of a synthetic asset paying the London Interbank Offered Rate (LIBOR), with a constant 3-month average maturity. The index is based on the assumed purchase at par value of a synthetic instrument having exactly its stated maturity and with a coupon equal to that day's 3-month LIBOR rate. Index returns assume reinvestment of dividends and, unlike Fund returns, do not reflect any fees, expenses or sales charges. It is not possible to invest directly in an index. The index defined here pertains to the "Value of $10,000 Investment" and "Value of $5 Million Investment" charts on pages 12-16. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 11 Performance Update | 9/30/17 Class A Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $10,000 investment made in Class A shares of Pioneer Multi-Asset Ultrashort Income Fund at public offering price during the periods shown, compared to that of the Bank of America (BofA) Merrill Lynch (ML) U.S. Dollar 3-Month LIBOR Index. Average Annual Total Returns (As of September 30, 2017) -------------------------------------------------------------------------------- BofA ML Net Public U.S. Dollar Asset Offering 3-Month Value Price LIBOR Period (NAV) (POP) Index -------------------------------------------------------------------------------- Life-of-Class (4/29/11) 1.36% 0.95% 0.45% 5 year 1.15 0.64 0.47 1 year 1.83 -0.75 1.02 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated August 1, 2017) -------------------------------------------------------------------------------- Gross -------------------------------------------------------------------------------- 0.61% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Pioneer Multi-Asset BofA ML U.S. Dollar Ultrashort Income Fund 3-Month LIBOR Index 4/11 $ 9,750 $10,000 9/11 $ 9,756 $10,009 9/12 $10,037 $10,058 9/13 $10,124 $10,090 9/14 $10,228 $10,114 9/15 $10,282 $10,140 9/16 $10,436 $10,190 9/17 $10,627 $10,294 Call 1-800-225-6292 or visit www.amundipioneer.com for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted. The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost. NAV results represent the percent change in net asset value per share. Returns would have been lower had sales charges been reflected. POP returns reflect deduction of maximum 2.50% sales charge. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ. Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. Please refer to the financial highlights for a more current expense ratio. 12 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 Performance Update | 9/30/17 Class C Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $10,000 investment made in Class C shares of Pioneer Multi-Asset Ultrashort Income Fund during the periods shown, compared to that of the Bank of America (BofA) Merrill Lynch (ML) U.S. Dollar 3-Month LIBOR Index. Average Annual Total Returns (As of September 30, 2017) -------------------------------------------------------------------------------- BofA ML U.S. Dollar 3-Month If If LIBOR Period Held Redeemed Index -------------------------------------------------------------------------------- Life-of-Class (4/29/11) 0.94% 0.94% 0.45% 5 year 0.82 0.82 0.47 1 year 1.40 1.40 1.02 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated August 1, 2017) -------------------------------------------------------------------------------- Gross -------------------------------------------------------------------------------- 0.93% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Pioneer Multi-Asset BofA ML U.S. Dollar Ultrashort Income Fund 3-Month LIBOR Index 4/11 $10,000 $10,000 9/11 $ 9,975 $10,009 9/12 $10,191 $10,058 9/13 $10,252 $10,090 9/14 $10,325 $10,114 9/15 $10,349 $10,140 9/16 $10,471 $10,190 9/17 $10,618 $10,294 Call 1-800-225-6292 or visit www.amundipioneer.com for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted. The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost. "If Held" results represent the percent change in net asset value per share. Returns would have been lower had sales charges been reflected. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ. Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. Please refer to the financial highlights for a more current expense ratio. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 13 Performance Update | 9/30/17 Class C2 Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $10,000 investment made in Class C2 shares of Pioneer Multi-Asset Ultrashort Income Fund during the periods shown, compared to that of the Bank of America (BofA) Merrill Lynch (ML) U.S. Dollar 3-Month LIBOR Index. Average Annual Total Returns (As of September 30, 2017) -------------------------------------------------------------------------------- BofA ML U.S. Dollar 3-Month If If LIBOR Period Held Redeemed Index -------------------------------------------------------------------------------- Life-of-Class (4/29/11) 0.93% 0.93% 0.45% 5 year 0.82 0.82 0.47 1 year 1.40 1.40 1.02 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated August 1, 2017) -------------------------------------------------------------------------------- Gross -------------------------------------------------------------------------------- 0.93% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Pioneer Multi-Asset BofA ML U.S. Dollar Ultrashort Income Fund 3-Month LIBOR Index 4/11 $10,000 $10,000 9/11 $ 9,975 $10,009 9/12 $10,191 $10,058 9/13 $10,250 $10,090 9/14 $10,324 $10,114 9/15 $10,336 $10,140 9/16 $10,468 $10,190 9/17 $10,615 $10,294 Call 1-800-225-6292 or visit www.amundipioneer.com for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted. The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost. Class C2 shares held for less than 1 year are subject to a 1% contingent deferred sales charge (CDSC). "If Held" results represent the percentage change in net asset value per share. Returns would have been lower had sales charges been reflected. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ. The performance shown for periods prior to the commencement of operations of Class C2 shares on August 1, 2013, is the net asset value performance of the Fund's Class C shares, which has not been restated to reflect any differences in expenses. For the period beginning August 1, 2013, the actual performance of Class C2 shares is reflected. Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. Please refer to the financial highlights for a more current expense ratio. 14 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 Performance Update | 9/30/17 Class K Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $5 million investment made in Class K shares of Pioneer Multi-Asset Ultrashort Income Fund during the periods shown, compared to that of the Bank of America (BofA) Merrill Lynch (ML) U.S. Dollar 3-Month LIBOR Index. Average Annual Total Returns (As of September 30, 2017) -------------------------------------------------------------------------------- BofA ML Net U.S. Dollar Asset 3-Month Value LIBOR Period (NAV) Index -------------------------------------------------------------------------------- Life-of-Class (4/29/11) 1.53% 0.45% 5 year 1.38 0.47 1 year 2.05 1.02 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated August 1, 2017) -------------------------------------------------------------------------------- Gross -------------------------------------------------------------------------------- 0.42% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $5 Million Investment Pioneer Multi-Asset BofA ML U.S. Dollar Ultrashort Income Fund 3-Month LIBOR Index 4/11 $5,000,000 $5,000,000 9/11 $5,004,864 $5,004,742 9/12 $5,148,808 $5,028,849 9/13 $5,208,133 $5,044,939 9/14 $5,273,102 $5,057,112 9/15 $5,312,089 $5,069,978 9/16 $5,403,049 $5,095,071 9/17 $5,513,754 $5,147,121 Call 1-800-225-6292 or visit www.amundipioneer.com for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted. The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost. The performance shown for Class K shares for the period prior to the commencement of operations of Class K shares on December 20, 2012, is the net asset value performance of the Fund's Class A shares, which has not been restated to reflect any differences in expenses, including Rule 12b-1 fees applicable to Class A shares. Since fees for Class A shares generally are higher than those of Class K shares, the performance of Class K shares prior to their inception would have been higher than the performance shown. For the period beginning on December 20, 2012, the actual performance of Class K shares is reflected. Class K shares are not subject to sales charges and are available for limited groups of eligible investors, including institutional investors. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ. Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. Please refer to the financial highlights for a more current expense ratio. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 15 Performance Update | 9/30/17 Class Y Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $5 million investment made in Class Y shares of Pioneer Multi-Asset Ultrashort Income Fund during the periods shown, compared to that of the Bank of America (BofA) Merrill Lynch (ML) U.S. Dollar 3-Month LIBOR Index. Average Annual Total Returns (As of September 30, 2017) -------------------------------------------------------------------------------- BofA ML Net U.S. Dollar Asset 3-Month Value LIBOR Period (NAV) Index -------------------------------------------------------------------------------- Life-of-Class (4/29/11) 1.52% 0.45% 5 year 1.28 0.47 1 year 1.84 1.02 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated August 1, 2017) -------------------------------------------------------------------------------- Gross -------------------------------------------------------------------------------- 0.50% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $5 Million Investment Pioneer Multi-Asset BofA ML U.S. Dollar Ultrashort Income Fund 3-Month LIBOR Index 4/11 $5,000,000 $5,000,000 9/11 $5,008,825 $5,004,742 9/12 $5,169,696 $5,028,849 9/13 $5,224,861 $5,044,939 9/14 $5,286,365 $5,057,112 9/15 $5,316,328 $5,069,978 9/16 $5,408,608 $5,095,071 9/17 $5,508,360 $5,147,121 Call 1-800-225-6292 or visit www.amundipioneer.com for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted. The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost. Class Y shares are not subject to sales charges and are available for limited groups of eligible investors, including institutional investors. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ. Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. Please refer to the financial highlights for a more current expense ratio. 16 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 Comparing Ongoing Fund Expenses As a shareowner in the Fund, you incur two types of costs: (1) ongoing costs, including management fees, distribution and/or service (12b-1) fees, and other Fund expenses; and (2) transaction costs, including sales charges (loads) on purchase payments. This example is intended to help you understand your ongoing expenses (in dollars) of investing in the Fund and to compare these costs with the ongoing costs of investing in other mutual funds. The example is based on an investment of $1,000 at the beginning of the Fund's latest six-month period and held throughout the six months. Using the Tables -------------------------------------------------------------------------------- Actual Expenses The first table below provides information about actual account values and actual expenses. You may use the information in this table, together with the amount you invested, to estimate the expenses that you paid over the period as follows: (1) Divide your account value by $1,000 Example: an $8,600 account value (divided by) $1,000 = 8.6 (2) Multiply the result in (1) above by the corresponding share class's number in the third row under the heading entitled "Expenses Paid During Period" to estimate the expenses you paid on your account during this period. Expenses Paid on a $1,000 Investment in Pioneer Multi-Asset Ultrashort Income Fund Based on actual returns from April 1, 2017, through September 30, 2017. -------------------------------------------------------------------------------- Share Class A C C2 K Y -------------------------------------------------------------------------------- Beginning Account $1,000.00 $1,000.00 $1,000.00 $1,000.00 $1,000.00 Value on 4/1/17 -------------------------------------------------------------------------------- Ending Account Value $1,007.80 $1,006.20 $1,006.20 $1,009.90 $1,008.50 (after expenses) on 9/30/17 -------------------------------------------------------------------------------- Expenses Paid $ 3.02 $ 4.63 $ 4.58 $ 1.91 $ 2.32 During Period* -------------------------------------------------------------------------------- * Expenses are equal to the Fund's annualized net expense ratio of 0.60%, 0.92%, 0.91%, 0.38% and 0.46% for Class A, Class C, Class C2, Class K, and Class Y shares, respectively, multiplied by the average account value over the period, multiplied by 183/365 (to reflect the one-half year period). Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 17 Hypothetical Example for Comparison Purposes The table below provides information about hypothetical account values and hypothetical expenses based on the Fund's actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the Fund's actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. You may use this information to compare the ongoing costs of investing in the Fund and other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other funds. Please note that the expenses shown in the tables are meant to highlight your ongoing costs only and do not reflect any transaction costs, such as sales charges (loads) that are charged at the time of the transaction. Therefore, the table below is useful in comparing ongoing costs only and will not help you determine the relative total costs of owning different funds. In addition, if these transaction costs were included, your costs would have been higher. Expenses Paid on a $1,000 Investment in Pioneer Multi-Asset Ultrashort Income Fund Based on a hypothetical 5% return per year before expenses, reflecting the period from April 1, 2017, through September 30, 2017. -------------------------------------------------------------------------------- Share Class A C C2 K Y -------------------------------------------------------------------------------- Beginning Account $1,000.00 $1,000.00 $1,000.00 $1,000.00 $1,000.00 Value on 4/1/17 -------------------------------------------------------------------------------- Ending Account Value $1,022.06 $1,020.46 $1,020.51 $1,023.16 $1,022.76 (after expenses) on 9/30/17 -------------------------------------------------------------------------------- Expenses Paid $ 3.04 $ 4.66 $ 4.61 $ 1.93 $ 2.33 During Period* -------------------------------------------------------------------------------- * Expenses are equal to the Fund's annualized net expense ratio of 0.60%, 0.92%, 0.91%, 0.38% and 0.46% for Class A, Class C, Class C2, Class K, and Class Y shares, respectively, multiplied by the average account value over the period, multiplied by 183/365 (to reflect the one-half year period). 18 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 Schedule of Investments | 9/30/17 (unaudited) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- UNAFFILIATED ISSUERS -- 99.4% ASSET BACKED SECURITIES -- 28.8% ENERGY -- 0.6% Oil & Gas Exploration & Production -- 0.6% 3,409,049 AXIS Equipment Finance Receivables IV LLC, 2.21%, 11/20/21 (144A) $ 3,399,331 7,000,000 1.38 1M LIBOR+ GM Financial Consumer Automobile 15bps Receivables Trust 2017-2, Floating Rate Note, 5/18/20 (144A) 7,001,231 6,800,000 1.98 1M LIBOR+ Master Credit Card Trust II Series 2016-1, 75bps Floating Rate Note, 9/23/19 (144A) 6,824,924 2,618,626 PRPM 2016-1 LLC, 4.0%, 9/27/21 (Step) (144A) 2,614,480 2,100,000 Wheels SPV 2 LLC, 1.88%, 4/20/26 (144A) 2,098,066 1,953,496 WVUE 2015-1, 4.5%, 9/25/20 (Step) (144A) 1,958,852 -------------- $ 23,896,884 -------------- Total Energy $ 23,896,884 -------------------------------------------------------------------------------------------------------------- MATERIALS -- 0.5% Steel -- 0.5% 2,481,628 2.14 1M LIBOR+ Aegis Asset Backed Securities Trust 90bps Mortgage Pass- Through Ctfs Series 2004-3, Floating Rate Note, 9/25/34 $ 2,499,710 1,464,926 1.96 1M LIBOR+ First NLC Trust 2005-2, Floating Rate 48bps Note, 9/25/35 1,471,966 5,096,020 1.72 1M LIBOR+ Home Equity Asset Trust 2005-6, 49bps Floating Rate Note, 12/25/35 5,113,793 205,000 1.69 1M LIBOR+ Home Equity Asset Trust 2005-7, 45bps Floating Rate Note, 1/25/36 205,221 134,657 1.96 1M LIBOR+ Mastr Asset Backed Securities Trust 72bps 2005-WMC1, Floating Rate Note, 3/25/35 134,946 517,120 1.91 1M LIBOR+ New Century Home Equity Loan Trust 67.5bps 2005-2, Floating Rate Note, 6/25/35 517,345 889,596 1.90 1M LIBOR+ Option One Mortgage Loan Trust 2005-1, 66bps Floating Rate Note, 2/25/35 887,062 3,640,916 1.68 1M LIBOR+ Option One Mortgage Loan Trust 2005-4 44bps Asset-Backed Certificates Series 2005-4, Floating Rate Note, 11/25/35 3,634,154 86,038 1.48 1M LIBOR+ RASC Series 2005-AHL3 Trust, Floating 24bps Rate Note, 9/25/35 86,031 4,301,835 1.93 1M LIBOR+ Wells Fargo Home Equity Asset-Backed 69bps Securities 2005-2 Trust, Floating Rate Note, 11/25/35 4,309,982 -------------- $ 18,860,210 -------------- Total Materials $ 18,860,210 -------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 19 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- TRANSPORTATION -- 0.01% Trucking -- 0.1% 12,592 1.64 1M LIBOR+ Hertz Fleet Lease Funding LP, Floating 40bps Rate Note, 4/10/28 (144A) $ 12,592 3,600,000 4.58 1M LIBOR+ Hertz Fleet Lease Funding LP, Floating 335bps Rate Note, 4/10/30 (144A) 3,701,317 -------------- $ 3,713,909 -------------- Total Transportation $ 3,713,909 -------------------------------------------------------------------------------------------------------------- CONSUMER SERVICES -- 0.1% Hotels, Resorts & Cruise Lines -- 0.1% 843,893 Westgate Resorts 2014-1 LLC, 2.15%, 12/20/26 (144A) $ 841,717 1,005,334 Westgate Resorts 2014-1 LLC, 5.5%, 12/20/26 (144A) 1,020,721 1,219,957 Westgate Resorts 2015-1 LLC, 2.75%, 5/20/27 (144A) 1,222,955 -------------- $ 3,085,393 -------------- Total Consumer Services $ 3,085,393 -------------------------------------------------------------------------------------------------------------- RETAILING -- 0.0%+ Automotive Retail -- 0.0%+ 850,000 2.74 1M LIBOR+ Hertz Fleet Lease Funding LP, Floating 150bps Rate Note, 4/10/28 (144A) $ 849,856 -------------- Total Retailing $ 849,856 -------------------------------------------------------------------------------------------------------------- HEALTH CARE EQUIPMENT & SERVICES -- 0.1% Pharmaceuticals -- 0.1% 4,059,726 Drug Royalty III LP Series 2017-1A Class A1, 4/15/27 $ 4,059,670 -------------- Total Health Care Equipment & Services $ 4,059,670 -------------------------------------------------------------------------------------------------------------- BANKS -- 26.0% Thrifts & Mortgage Finance -- 26.0% 3,813,012 1.46 1M LIBOR+ 321 Henderson Receivables I LLC, 23bps Floating Rate Note, 11/15/40 (144A) $ 3,628,582 3,311,702 1.43 1M LIBOR+ 321 Henderson Receivables I LLC, 20bps Floating Rate Note, 12/15/41 (144A) 3,232,025 732,372 1.43 1M LIBOR+ 321 Henderson Receivables I LLC, 20bps Floating Rate Note, 3/15/41 (144A) 714,380 480,062 1.58 1M LIBOR+ 321 Henderson Receivables I LLC, 35bps Floating Rate Note, 9/15/45 (144A) 466,440 1,904,932 1.43 1M LIBOR+ 321 Henderson Receivables II LLC, 20bps Floating Rate Note, 9/15/41 (144A) 1,800,846 409,625 1.99 1M LIBOR+ ABFC 2005-HE2 Trust, Floating Rate 75bps Note, 6/25/35 411,868 26,972 1.86 1M LIBOR+ ABFC 2005-WF1 Trust, Floating Rate 62bps Note, 12/25/34 26,979 The accompanying notes are an integral part of these financial statements. 20 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 1,920,819 1.91 1M LIBOR+ ABFC 2005-WMC1 Trust, Floating Rate 67.5bps Note, 6/25/35 $ 1,926,382 1,149,741 1.44 1M LIBOR+ ACE Securities Corp Home Equity Loan 20bps Trust Series 2006-ASAP2, Floating Rate Note, 3/25/36 1,149,321 271,775 1.71 1M LIBOR+ Aegis Asset Backed Securities Trust 47bps 2005-3, Floating Rate Note, 8/25/35 271,709 44,796 2.34 1M LIBOR+ Aegis Asset Backed Securities Trust 90bps Mortgage Pass-Through Ctfs Series 2004-3, Floating Rate Note, 9/25/34 44,849 467,050 2.34 1M LIBOR+ Aegis Asset Backed Securities Trust 110bps Mortgage Pass- Through Certificates Series 2004-4, Floating Rate Note, 10/25/34 470,528 45,832 1.61 1M LIBOR+ Aegis Asset Backed Securities Trust 37bps Mortgage Pass-Through Ctfs Ser 2005-4, Floating Rate Note, 10/25/35 45,843 300,000 Ally Auto Receivables Trust 2014-2, 2.99%, 6/15/21 303,030 4,600,000 1.63 1M LIBOR+ Ally Master Owner Trust, Floating Rate 40bps Note, 2/15/21 4,608,568 7,000,000 1.57 1M LIBOR+ Ally Master Owner Trust, Floating Rate 34bps Note, 6/15/21 7,009,097 1,237,773 Alterna Funding II LLC, 3.2%, 2/15/24 (144A) 1,230,811 59,555 American Credit Acceptance Receivables Trust 2016-1A, 2.37%, 5/12/20 (144A) 59,575 7,500,000 American Credit Acceptance Receivables Trust 2016-4, 2.11%, 2/12/21 (144A) 7,505,252 4,100,000 American Credit Acceptance Receivables Trust 2017-1, 2.39%, 2/16/21 (144A) 4,101,474 5,188,331 American Credit Acceptance Receivables Trust 2017-2, 1.84%, 7/13/20 (144A) 5,189,969 4,650,000 American Credit Acceptance Receivables Trust 2017-3, 1.82%, 3/10/20 (144A) 4,650,837 2,200,000 American Credit Acceptance Receivables Trust 2017-3, 2.25%, 1/11/21 (144A) 2,196,312 235,000 2.49 1M LIBOR+ American Express Credit Account Master 126bps Trust, Floating Rate Note, 9/15/20 236,074 475,000 1.47 1M LIBOR+ American Express Credit Account Secured 24bps Note Trust 2012-4, Floating Rate Note, 5/15/20 475,052 204,110 1.98 1M LIBOR+ AmeriCredit Automobile Receivables 75bps 2016-1, Floating Rate Note, 6/10/19 204,147 699,254 1.79 1M LIBOR+ AmeriCredit Automobile Receivables 56bps Trust 2016-3, Floating Rate Note, 11/8/19 699,816 2,367,517 1.53 1M LIBOR+ AmeriCredit Automobile Receivables 30bps Trust 2017-1, Floating Rate Note, 5/18/20 2,367,923 3,000,000 1.48 1M LIBOR+ AmeriCredit Automobile Receivables 25bps Trust 2017-2, Floating Rate Note, 9/18/20 2,999,886 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 21 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 907,149 1.92 1M LIBOR+ Ameriquest Mortgage Securities Inc 69bps Asset-Backed Pass-Through Ctfs Ser 2005-R5, Floating Rate Note, 7/25/35 $ 909,565 188,126 1.57 1M LIBOR+ Ameriquest Mortgage Securities, Inc., 33bps Asset Backed Pass-Through Ctfs Series 2005-R11, Floating Rate Note, 1/25/36 187,975 116,297 2.27 1M LIBOR+ Amortizing Residential Collateral Trust 103.5bps 2002-BC5, Floating Rate Note, 7/25/32 115,163 261,342 1.58 1M LIBOR+ Argent Securities Inc Asset-Backed Pass- 34bps Through Certificates Series 2005-W3, Floating Rate Note, 11/25/35 260,937 3,400,000 ARI Fleet Lease Trust 2017-A, 1.91%, 4/15/26 (144A) 3,402,075 410,000 Ascentium Equipment Receivables 2015-1 LLC, 5.92%, 6/12/23 (144A) 414,432 2,042,190 Ascentium Equipment Receivables 2016-2 Trust, 1.46%, 4/10/19 (144A) 2,040,452 3,500,000 Ascentium Equipment Receivables 2017-1 Trust, 1.87%, 7/10/19 (144A) 3,500,668 486,303 1.44 1M LIBOR+ Asset Backed Securities Corp Home Equity 20bps Loan Trust Series AEG 2006-HE1, Floating Rate Note, 1/25/36 482,468 1,274,330 2.18 1M LIBOR+ Asset Backed Securities Corp Home Equity 94.5bps Loan Trust Series NC 2005-HE4, Floating Rate Note, 5/25/35 1,282,813 871,233 1.67 1M LIBOR+ Asset Backed Securities Corp Home Equity 43bps Loan Trust Series NC 2005-HE8, Floating Rate Note, 11/25/35 871,373 62,572 1.92 1M LIBOR+ Asset-Backed Pass-Through Certificates 69bps Series 2004-R2, Floating Rate Note, 4/25/34 62,784 575,373 1.85 1M LIBOR+ Asset-Backed Pass-Through Certificates 62bps Series 2004-R2, Floating Rate Note, 4/25/34 576,649 7,020,000 1.62 1M LIBOR+ BA Credit Card Trust, Floating Rate Note, 39bps 10/15/21 7,050,135 6,975,000 1.52 1M LIBOR+ Barclays Dryrock Issuance Trust, Floating 30bps Rate Note, 5/15/23 6,984,803 25,318 1M LIBOR+ Bayview Financial Acquisition Trust, 6.205%, 112.5bps 5/28/37 (Step) 26,212 1,407,121 2.36 1M LIBOR+ Bayview Financial Acquisition Trust, Floating 112.5bps Rate Note, 5/28/44 1,407,968 3,258 2.24 1M LIBOR+ Bayview Financial Mortgage Pass-Through 100.5bps Certificates Series 2004-D, Floating Rate Note, 8/28/44 3,258 671,584 1.98 1M LIBOR+ Bayview Financial Mortgage Pass-Through 50bps Trust 2005-C, Floating Rate Note, 6/28/44 670,320 57,287 BCC Funding Corp X, 2.224%, 10/20/20 (144A) 57,232 The accompanying notes are an integral part of these financial statements. 22 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 2,600,000 BCC Funding Corp X, 4.544%, 12/21/20 (144A) $ 2,632,344 1,281,207 1.99 1M LIBOR+ Bear Stearns Asset Backed Securities I 75bps Trust 2005-FR1, Floating Rate Note, 6/25/35 1,283,806 164,222 1.72 1M LIBOR+ Bear Stearns Asset Backed Securities I 48bps Trust 2005-HE12, Floating Rate Note, 12/25/35 164,591 1,442,018 1.89 1M LIBOR+ Bear Stearns Asset Backed Securities I 66bps Trust 2005-TC1, Floating Rate Note, 5/25/35 1,445,832 2,435,145 1.64 1M LIBOR+ Bear Stearns Asset Backed Securities I 40bps Trust 2006-EC2, Floating Rate Note, 2/25/36 2,437,813 150,410 2.44 1M LIBOR+ Bear Stearns Asset Backed Securities Trust 120bps 2004-2, Floating Rate Note, 8/25/34 150,580 208,323 2.38 1M LIBOR+ Bear Stearns Asset Backed Securities Trust 57bps 2004-SD3, Floating Rate Note, 9/25/34 208,350 3,601 2.04 1M LIBOR+ Bear Stearns Asset Backed Securities Trust 80bps 2005-SD1, Floating Rate Note, 8/25/43 3,601 277,891 1.71 1M LIBOR+ Bear Stearns Asset Backed Securities Trust 47bps 2005-SD2, Floating Rate Note, 3/25/35 277,427 285,743 1.64 1M LIBOR+ Bear Stearns Asset Backed Securities Trust 40bps 2005-SD2, Floating Rate Note, 3/25/35 285,210 785,020 1.61 Bear Stearns Asset Backed Securities Trust 2006-SD1, Variable Rate Note, 4/25/36 767,996 1,866,539 1.62 1M LIBOR+ Bear Stearns Asset Backed Securities Trust 38bps 2006-SD2, Floating Rate Note, 6/25/36 1,837,307 300,406 1.73 1M LIBOR+ Bear Stearns Asset Backed Securities Trust 49bps 2006-SD2, Floating Rate Note, 6/25/36 296,069 306,607 2.24 1M LIBOR+ Bear Stearns Structured Products Trust 100bps 2007-EMX1, Floating Rate Note, 3/25/37 (144A) 307,782 2,700,000 2.08 1M LIBOR+ Cabela's Credit Card Master Note Trust, 85bps Floating Rate Note, 6/15/22 2,724,240 2,200,000 1.68 1M LIBOR+ Cabela's Credit Card Master Note Trust, 45bps Floating Rate Note, 7/15/22 2,208,694 493,080 California Republic Auto Receivables Trust 2016-2, 1.34%, 3/15/19 493,020 1,050,000 California Republic Auto Receivables Trust 2016-2, 1.56%, 7/15/20 1,049,411 1,839,810 California Republic Auto Receivables Trust 2017-1, 1.55%, 11/15/19 1,839,454 2,696,958 CAM Mortgage Trust 2016-2, 3.25%, 6/15/57 (Step) (144A) 2,700,181 550,000 CarMax Auto Owner Trust 2015-2, 2.39%, 3/15/21 552,651 289,378 1.76 1M LIBOR+ CarMax Auto Owner Trust 2016-1, Floating 53bps Rate Note, 4/15/19 289,522 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 23 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 3,050,000 1.41 1M LIBOR+ CarMax Auto Owner Trust 2017-3, Floating 18bps Rate Note, 9/15/20 $ 3,051,195 1,842,267 1.42 1M LIBOR+ Carrington Mortgage Loan Trust Series 18bps 2006-OPT1, Floating Rate Note, 12/26/35 1,835,566 519,217 Cazenovia Creek Funding I LLC, 2.0%, 12/10/23 (144A) 516,945 316,640 Cazenovia Creek Funding I LLC, 2.773%, 12/10/23 (144A) 314,859 1,424,047 CCG Receivables Trust 2016-1, 1.69%, 9/14/22 (144A) 1,423,663 2,515,892 CCG Receivables Trust 2017-1, 1.35%, 6/14/18 (144A) 2,515,914 218,498 3.65 Centex Home Equity Loan Trust 2003-A, Floating Rate Note, 3/25/33 218,097 10,645,000 1.53 1M LIBOR+ Chase Issuance Trust, Floating Rate Note, 30bps 1/18/22 10,685,362 200,000 1.49 1M LIBOR+ Chase Issuance Trust, Floating Rate Note, 26bps 12/16/19 200,067 4,645,000 1.63 1M LIBOR+ Chase Issuance Trust, Floating Rate Note, 40bps 3/15/24 4,660,769 2,420,000 1.51 1M LIBOR+ Chase Issuance Trust, Floating Rate Note, 28bps 4/15/20 2,423,137 1,845,590 2.38 1M LIBOR+ Chesapeake Funding II LLC, Floating Rate 115bps Note, 3/15/28 (144A) 1,852,497 2,201,167 2.23 1M LIBOR+ Chesapeake Funding II LLC, Floating Rate 100bps Note, 6/15/28 (144A) 2,214,705 6,570,000 1.68 1M LIBOR+ Chesapeake Funding II LLC, Floating Rate 45bps Note, 7/15/29 (144A) 6,586,221 11,000,000 1.57 1M LIBOR+ Chesapeake Funding II LLC, Floating Rate 34bps Note, 8/15/29 (144A) 11,012,854 4,700,000 1.48 1M LIBOR+ Citibank Credit Card Issuance Trust, Floating 25bps Rate Note, 1/19/21 4,709,571 7,984,000 2.39 1M LIBOR+ Citibank Credit Card Issuance Trust, Floating 115bps Rate Note, 1/23/20 8,012,255 4,500,000 1.45 1M LIBOR+ Citibank Credit Card Issuance Trust, Floating 22bps Rate Note, 4/7/22 4,511,149 4,050,000 2.61 1M LIBOR+ Citibank Credit Card Issuance Trust, Floating 137.5bps Rate Note, 5/20/20 4,084,505 2,980,000 1.52 1M LIBOR+ Citibank Credit Card Issuance Trust, Floating 28bps Rate Note, 5/26/20 2,984,709 2,580,000 1.66 1M LIBOR+ Citibank Credit Card Issuance Trust, Floating 42bps Rate Note, 7/24/20 2,587,639 8,200,000 1.60 1M LIBOR+ Citibank Credit Card Issuance Trust, Floating 37bps Rate Note, 8/8/24 8,229,522 4,771,000 1.66 1M LIBOR+ Citibank Credit Card Issuance Trust, Floating 43bps Rate Note, 9/10/20 4,789,129 The accompanying notes are an integral part of these financial statements. 24 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 784,879 Citicorp Residential Mortgage Trust Series 2006-1, 5.40402%, 7/25/36 (Step) $ 787,238 457,943 1.91 1M LIBOR+ Citigroup Mortgage Loan Trust Series 67.5bps 2005-OPT3 Asset Backed Pass-Through Certifi, Floating Rate Note, 5/25/35 458,680 164,780 2.26 1M LIBOR+ Citigroup Mortgage Loan Trust, Inc., 102bps Floating Rate Note, 11/25/34 166,080 561,648 1.99 1M LIBOR+ Citigroup Mortgage Loan Trust, Inc., 75bps Floating Rate Note, 5/25/35 (144A) 560,973 5,800,000 1.46 1M LIBOR+ Citigroup Mortgage Loan Trust, Inc., 22bps Floating Rate Note, 8/25/36 5,736,362 2,850,000 1.37 1M LIBOR+ CNH Equipment Trust 2017-B, Floating 14bps Rate Note, 11/16/20 2,850,791 691,429 2.69 1M LIBOR+ Commonbond Student Loan Trust 2016-B, 145bps Floating Rate Note, 10/25/40 (144A) 699,879 7,016,073 2.08 1M LIBOR+ Commonbond Student Loan Trust 85bps 2017-A-GS, Floating Rate Note, 5/25/41 (144A) 7,060,969 1,775,356 Conn Funding II LP, 2.73%, 7/15/19 (144A) 1,776,368 1,800,000 Conn Funding II LP, 5.11%, 2/15/20 (144A) 1,811,977 326,144 Conn's Receivables Funding 2016-B LLC, 3.73%, 10/15/18 (144A) 326,382 500,000 Conn's Receivables Funding 2016-B LLC, 7.34%, 3/15/19 (144A) 509,327 314,224 3.73 1M LIBOR+ Conseco Finance Home Equity Loan 250bps Trust 2002-B, Floating Rate Note, 6/15/32 306,885 325,268 2.73 1M LIBOR+ Conseco Finance Home Equity Loan 150bps Trust 2002-C, Floating Rate Note, 4/15/32 323,817 378,384 2.29 1M LIBOR+ Countrywide Asset-Backed Certificates, 105bps Floating Rate Note, 1/25/35 380,409 1,656,429 2.14 1M LIBOR+ Countrywide Asset-Backed Certificates, 90bps Floating Rate Note, 3/25/35 1,655,812 8,274,473 1.47 1M LIBOR+ Countrywide Asset-Backed Certificates, 23bps Floating Rate Note, 4/25/36 8,262,514 124,747 1.92 1M LIBOR+ Countrywide Asset-Backed Certificates, 68bps Floating Rate Note, 6/25/33 (144A) 123,874 26,670 2.14 1M LIBOR+ Countrywide Asset-Backed Certificates, 90bps Floating Rate Note, 6/25/33 (144A) 26,572 511,234 1.50 1M LIBOR+ Countrywide Asset-Backed Certificates, 26bps Floating Rate Note, 7/25/36 509,677 1,915,000 CPS Auto Receivables Trust 2015-A, 4.0%, 2/16/21 (144A) 1,951,625 316,128 CPS Auto Receivables Trust 2015-B, 1.65%, 11/15/19 (144A) 316,130 575,711 CPS Auto Receivables Trust 2016-A, 2.25%, 10/15/19 (144A) 576,442 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 25 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 400,000 CPS Auto Receivables Trust 2016-C, 2.48%, 9/15/20 (144A) $ 401,056 2,707,759 CPS Auto Receivables Trust 2017-C, 1.78%, 9/15/20 (144A) 2,706,437 1,302,255 CPS Auto Trust, 1.5%, 6/15/20 (144A) 1,299,816 1,435,205 CPS Auto Trust, 1.68%, 8/17/20 (144A) 1,433,511 2,441,779 1.48 1M LIBOR+ Credit Suisse Seasoned Loan Trust 24bps 2006-1, Floating Rate Note, 10/25/34 (144A) 2,427,830 144,440 1.35 1M LIBOR+ Credit-Based Asset Servicing & 24bps Securitization LLC, Floating Rate Note, 10/25/36 144,225 131,153 1.90 1M LIBOR+ Credit-Based Asset Servicing & 66bps Securitization LLC, Floating Rate Note, 7/25/34 131,331 1,312,302 1.89 1M LIBOR+ CSFB Mortgage-Backed Pass-Through 65bps Certificates Series 2005-AGE1, Floating Rate Note, 2/25/32 1,300,164 833,968 1.51 1M LIBOR+ CSMC Trust 2006-CF3, Floating Rate 54bps Note, 10/27/36 (144A) 830,791 5,970,760 2.36 1M LIBOR+ CWABS Asset-Backed Certificates Trust 112.5bps 2004-10, Floating Rate Note, 12/25/34 6,070,177 1,854,841 2.29 1M LIBOR+ CWABS Asset-Backed Certificates Trust 105bps 2004-7, Floating Rate Note, 12/25/34 1,860,969 3,176,371 1.47 1M LIBOR+ CWABS Asset-Backed Certificates Trust 23bps 2005-14, Floating Rate Note, 4/25/36 3,174,389 1,300,000 Dell Equipment Finance Trust 2017-1, 1.86%, 6/24/19 (144A) 1,300,700 221 Delta Funding Home Equity Loan Trust 1997-2, 7.04%, 6/25/27 213 5,915,000 1.58 1M LIBOR+ Discover Card Execution Note Trust, 35bps Floating Rate Note, 8/17/20 5,920,831 2,457,677 2.94 1M LIBOR+ DRB Prime Student Loan Trust 2015-D, 170bps Floating Rate Note, 1/25/40 (144A) 2,519,350 2,112,319 3.04 1M LIBOR+ DRB Prime Student Loan Trust 2016-B, 180bps Floating Rate Note, 6/25/40 (144A) 2,175,581 5,016,147 2.09 1M LIBOR+ DRB Prime Student Loan Trust 2017-A, 85bps Floating Rate Note, 5/27/42 (144A) 5,051,060 3,750,000 Drive Auto Receivables Trust 2017-1, 2.36%, 3/15/21 3,756,514 3,500,000 1.57 Drive Auto Receivables Trust 2017-1, Floating Rate Note, 5/15/19 3,500,483 700,000 Drive Auto Receivables Trust 2017-2, 2.25%, 6/15/21 700,479 2,600,000 1.51 1M LIBOR+ Drive Auto Receivables Trust 2017-2, 28bps Floating Rate Note, 8/15/19 2,599,999 513,421 Drive Auto Receivables Trust 2017-A, 1.48%, 3/15/19 (144A) 513,420 The accompanying notes are an integral part of these financial statements. 26 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 2,000,000 Drive Auto Receivables Trust 2017-B, 2.2%, 5/15/20 (144A) $ 2,004,145 1,653,175 4.15 3M LIBOR+ Drug Royalty II LP 2, Floating Rate Note, 285bps 7/15/23 (144A) 1,669,080 54,324 DT Auto Owner Trust 2016-3, 1.75%, 11/15/19 (144A) 54,332 4,500,000 DT Auto Owner Trust 2017-1, 2.26%, 2/15/21 (144A) 4,497,457 1,780,798 DT Auto Owner Trust 2017-2, 1.72%, 5/15/20 (144A) 1,780,964 1,700,000 DT Auto Owner Trust 2017-2, 2.44%, 2/15/21 (144A) 1,703,228 1,812,981 3.09 1M LIBOR+ Earnest Student Loan Program 2016-C 185bps LLC, Floating Rate Note, 10/27/36 (144A) 1,860,952 1,590,871 2.64 1M LIBOR+ Earnest Student Loan Program 2016-D 140bps LLC, Floating Rate Note, 1/25/41 (144A) 1,616,725 6,240,126 2.23 1M LIBOR+ Earnest Student Loan Program 2017-A 100bps LLC, Floating Rate Note, 1/25/41 (144A) 6,240,025 5,053,485 Engs Commercial Finance Trust 2016-1, 2.63%, 2/22/22 (144A) 5,042,464 882,150 Enterprise Fleet Financing LLC, 1.59%, 2/22/21 (144A) 881,882 1,650,484 Enterprise Fleet Financing LLC, 1.74%, 2/22/22 (144A) 1,649,176 3,550,000 1.73 1M LIBOR+ Evergreen Credit Card Trust Series 50bps 2016-3, Floating Rate Note, 11/16/20 (144A) 3,564,280 36,725 Exeter Automobile Receivables Trust 2015-2, 1.54%, 11/15/19 (144A) 36,720 2,219,678 Exeter Automobile Receivables Trust 2017-1, 1.96%, 3/15/21 (144A) 2,215,259 7,255,304 Exeter Automobile Receivables Trust 2017-2, 2.11%, 6/15/21 (144A) 7,265,209 3,000,000 Exeter Automobile Receivables Trust 2017-3, 2.05%, 12/15/21 (144A) 2,997,702 4,743,364 1.76 1M LIBOR+ FBR Securitization Trust, Floating Rate 52bps Note, 10/25/35 4,745,741 195,203 1.98 1M LIBOR+ FBR Securitization Trust, Floating Rate 74bps Note, 11/25/35 194,970 783,862 1.95 1M LIBOR+ FFMLT Trust 2005-FF2, Floating Rate 72bps Note, 3/25/35 785,014 5,065,391 1.48 1M LIBOR+ Fieldstone Mortgage Investment Trust 49bps Series 2005-3, Floating Rate Note, 2/25/36 4,994,292 2,700,000 1.39 1M LIBOR+ Fifth Third Auto Trust 2017-1, Floating 15bps Rate Note, 4/15/20 2,700,488 57,044 2.54 1M LIBOR+ First Franklin Mortgage Loan Trust 130bps 2003-FFC, Floating Rate Note, 11/25/32 56,942 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 27 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 97,551 2.09 1M LIBOR+ First Franklin Mortgage Loan Trust 85.5bps 2004-FF4, Floating Rate Note, 6/25/34 $ 96,793 287,258 2.06 1M LIBOR+ First Franklin Mortgage Loan Trust 82.5bps 2004-FF8, Floating Rate Note, 10/25/34 288,601 740,401 2.04 1M LIBOR+ First Franklin Mortgage Loan Trust 81bps 2005-FFH2, Floating Rate Note, 4/25/35 (144A) 743,774 2,065,288 1.46 1M LIBOR+ First Franklin Mortgage Loan Trust 24bps 2006-FF1, Floating Rate Note, 1/25/36 2,063,677 34,125 1.48 1M LIBOR+ First Franklin Mortgage Loan Trust 22bps 2006-FF1, Floating Rate Note, 1/25/36 34,123 409,310 1.50 1M LIBOR+ First Franklin Mortgage Loan Trust Series 26bps 2005-FF12, Floating Rate Note, 11/25/36 409,211 1,229,807 First Investors Auto Owner Trust 2017-1, 1.69%, 4/15/21 (144A) 1,228,061 4,222,853 First Investors Auto Owner Trust 2017-2, 1.86%, 10/15/21 (144A) 4,220,176 2,200,000 1.63 1M LIBOR+ First National Master Note Trust 2017-1, 40bps Floating Rate Note, 4/18/22 2,203,805 2,275,548 Flagship Credit Auto Trust 2015-2, 1.98%, 10/15/20 (144A) (e) 2,278,038 1,062,773 Flagship Credit Auto Trust 2015-3, 2.38%, 10/15/20 (144A) 1,066,278 474,601 Flagship Credit Auto Trust 2016-3, 1.61%, 12/15/19 (144A) 474,478 2,630,276 Flagship Credit Auto Trust 2017-1, 1.93%, 12/15/21 (144A) 2,631,564 7,046,769 Flagship Credit Auto Trust 2017-2, 1.85%, 7/15/21 (144A) 7,043,104 748,750 FNA 2015-1 Trust, 3.24%, 12/10/23 (144A) 745,350 73,925 1.63 1M LIBOR+ Ford Credit Auto Owner Trust 2016-A, 40bps Floating Rate Note, 12/15/18 73,936 749,655 1.54 1M LIBOR+ Ford Credit Auto Owner Trust 2016-B, 31bps Floating Rate Note, 3/15/19 749,949 3,323,046 1.35 1M LIBOR+ Ford Credit Auto Owner Trust 2017-A, 12bps Floating Rate Note, 12/15/19 3,324,549 7,500,000 1.30 1M LIBOR+ Ford Credit Auto Owner Trust 2017-B, 7bps Floating Rate Note, 5/15/20 7,503,752 4,900,000 1.69 1M LIBOR+ Ford Credit Floorplan Master Owner Trust A, 46bps Floating Rate Note, 11/15/21 4,916,580 4,000,000 2.13 1M LIBOR+ Ford Credit Floorplan Master Owner Trust A, 90bps Floating Rate Note, 2/15/21 4,033,486 3,500,000 1.85 1M LIBOR+ Ford Credit Floorplan Master Owner Trust A, 62bps Floating Rate Note, 7/15/21 3,521,724 5,362,017 Foursight Capital Automobile Receivables Trust 2016-1, 2.87%, 10/15/21 (144A) 5,382,597 7,047,216 Foursight Capital Automobile Receivables Trust 2017-1, 2.37%, 4/15/22 (144A) 7,035,626 The accompanying notes are an integral part of these financial statements. 28 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 409,150 1.95 1M LIBOR+ Fremont Home Loan Trust 2005-2, 72bps Floating Rate Note, 6/25/35 $ 410,243 8,069,572 1.47 1M LIBOR+ Fremont Home Loan Trust 2005-E, 23bps Floating Rate Note, 1/25/36 8,011,907 5,818,591 GCAT 2017-1 LLC, 3.375%, 3/25/47 (Step) (144A) 5,795,135 3,865,031 GCAT 2017-4 LLC, 3.2282%, 5/25/22 (Step) (144A) 3,877,397 6,259,473 1.46 1M LIBOR+ GE-WMC Asset-Backed Pass-Through 22.5bps Certificates Series 2005-2, Floating Rate Note, 12/25/35 6,245,553 43,834 GLC Trust 2013-1, 3.0%, 7/15/21 (144A) 43,177 743,298 GLS Auto Receivables Trust 2016-1, 2.73%, 10/15/20 (144A) 743,183 8,600,000 GLS Auto Receivables Trust 2017-1, 2.67%, 4/15/21 (144A) 8,594,263 2,600,000 1.35 1M LIBOR+ GM Financial Consumer Automobile 12bps 2017-1, Floating Rate Note, 3/16/20 (144A) 2,601,096 306,731 4.54 GMACM Home Equity Loan Trust 2002-HE4, Variable Rate Note, 10/25/32 305,578 1,005,221 GMAT 2013-1 Trust, 6.9669%, 8/25/53 (Step) 1,006,770 2,133,365 GMAT 2015-1 Trust, 4.25%, 9/25/20 (Step) (144A) 2,133,365 4,700,000 1.80 1M LIBOR+ GMF Floorplan Owner Revolving Trust, 57bps Floating Rate Note, 1/18/22 (144A) 4,726,790 8,725,000 1.73 1M LIBOR+ GMF Floorplan Owner Revolving Trust, 50bps Floating Rate Note, 5/15/20 (144A) 8,744,341 2,100,000 2.08 1M LIBOR+ GMF Floorplan Owner Revolving Trust, 85bps Floating Rate Note, 5/17/21 (144A) 2,120,370 4,000,000 1.83 1M LIBOR+ Golden Credit Card Trust, Floating Rate 60bps Note, 1/15/20 (144A) 4,003,024 150,000 1.67 1M LIBOR+ Golden Credit Card Trust, Floating Rate 44bps Note, 2/15/20 (144A) 150,190 2,200,000 1.63 1M LIBOR+ Golden Credit Card Trust, Floating Rate 40bps Note, 2/15/21 (144A) 2,207,891 590,000 1.68 1M LIBOR+ Golden Credit Card Trust, Floating Rate 45bps Note, 3/15/21 (144A) 592,406 5,000,000 Green Tree Agency Advance Funding Trust I, 3.1216%, 10/15/48 (144A) 4,971,300 906,356 2.29 1M LIBOR+ Green Tree Mortgage Loan Trust 2005-HE1, 70bps Floating Rate Note, 12/25/32 (144A) 905,122 248,242 1.89 1M LIBOR+ GSAA Home Equity Trust 2004-11, 66bps Floating Rate Note, 12/25/34 250,356 669,782 2.06 1M LIBOR+ GSAA Trust, Floating Rate Note, 55bps 6/25/35 665,562 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 29 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 2,778,233 2.21 1M LIBOR+ GSAMP Trust 2004-HE2, Floating Rate 97.5bps Note, 9/25/34 $ 2,806,286 599,503 2.21 1M LIBOR+ GSAMP Trust 2004-SEA2, Floating Rate 65bps Note, 3/25/34 599,818 129,229 1.99 1M LIBOR+ GSAMP Trust 2005-HE1, Floating Rate 75bps Note, 12/25/34 129,282 571,662 1.42 1M LIBOR+ GSAMP Trust 2006-HE2, Floating Rate 18bps Note, 3/25/46 571,453 788,523 2.59 1M LIBOR+ GSRPM Mortgage Loan Trust 2003-2, 135bps Floating Rate Note, 6/25/33 785,379 1,941,149 1.54 1M LIBOR+ GSRPM Mortgage Loan Trust 2006-1, 30bps Floating Rate Note, 3/25/35 (144A) 1,922,748 928,215 1.54 1M LIBOR+ GSRPM Mortgage Loan Trust 2006-2, 30bps Floating Rate Note, 9/25/36 (144A) 926,942 944,586 Hero Residual Funding 2016-1R, 4.5%, 9/21/42 (144A) 939,863 4,400,000 1.88 1M LIBOR+ Hertz Fleet Lease Funding LP, Floating 65bps Rate Note, 4/10/31 (144A) 4,404,843 3,200,000 2.74 1M LIBOR+ Hertz Fleet Lease Funding LP, Floating 150bps Rate Note, 7/10/29 (144A) 3,201,687 2,600,000 3.53 1M LIBOR+ Hertz Fleet Lease Funding LP, Floating 230bps Rate Note, 7/10/29 (144A) 2,589,065 116,585 1.62 1M LIBOR+ Home Equity Asset Trust 2005-7, Floating 45bps Rate Note, 1/25/36 116,641 3,196,361 1.61 1M LIBOR+ Home Equity Mortgage Loan Asset-Backed 37bps Trust Series INABS 2005-C, Floating Rate Note, 10/25/35 3,195,355 143,379 3.14 1M LIBOR+ Home Equity Mortgage Trust, Floating Rate 190bps Note, 10/25/34 141,405 1,283,318 Honor Automobile Trust Securitization 2016-1A, 2.94%, 11/15/19 (144A) 1,288,007 1,570,000 1.61 1M LIBOR+ HSI Asset Securitization Corp Trust 37bps 2006-OPT2, Floating Rate Note, 1/25/36 1,561,040 191,368 1.78 1M LIBOR+ Hyundai Auto Lease Securitization Trust 55bps 2016-A, Floating Rate Note, 7/16/18 (144A) 191,417 274,811 Invitation Homes Trust 2014-SFR3 Class D, 3.51%, 12/17/31 274,810 310,925 2.74 1M LIBOR+ Irwin Whole Loan Home Equity Trust 100bps 2003-C, Floating Rate Note, 6/25/28 308,534 300,685 1.97 1M LIBOR+ IXIS Real Estate Capital Trust 2005-HE3, 73.5bps Floating Rate Note, 12/25/35 301,182 2,600,000 1.34 1M LIBOR+ John Deere Owner Trust 2017-B, Floating 11bps Rate Note, 4/15/20 2,601,317 1,011,275 2.02 1M LIBOR+ JP Morgan Mortgage Acquisition Corp 78bps 2005-FLD1, Floating Rate Note, 7/25/35 1,013,701 4,500,000 2.21 JP Morgan Mortgage Acquisition Corp 2005-FLD1, Floating Rate Note, 7/25/35 4,537,876 The accompanying notes are an integral part of these financial statements. 30 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 233,612 1.46 1M LIBOR+ JP Morgan Mortgage Acquisition Corp 22bps 2005-FRE1, Floating Rate Note, 10/25/35 $ 233,474 78,920 1.41 1M LIBOR+ JP Morgan Mortgage Acquisition Trust 17bps 2006-NC1, Floating Rate Note, 4/25/36 78,738 10,745,000 1.94 1M LIBOR+ Lake Country Mortgage Loan Trust 70bps 2006-HE1, Floating Rate Note, 7/25/34 (144A) 10,661,086 3,054,092 Laurel Road Prime Student Loan Trust 2017-B, 1.63%, 8/25/42 (144A) 3,053,772 3,505,350 Leaf Receivables Funding 12 LLC, 1.72%, 5/15/19 (144A) 3,505,134 1,763,719 2.04 1M LIBOR+ Lehman XS Trust Series 2005-4, Floating 80bps Rate Note, 10/25/35 1,741,176 4,773,668 1.69 1M LIBOR+ Long Beach Mortgage Loan Trust 23bps 2006-WL1, Floating Rate Note, 1/25/46 4,774,184 5,850,000 1.49 1M LIBOR+ MBNA Credit Card Master Note Trust, 26bps Floating Rate Note, 8/16/21 5,860,373 612,716 2.10 1M LIBOR+ Merrill Lynch Mortgage Investors Trust 86bps Series 2004-OPT1, Floating Rate Note, 6/25/35 595,732 1,557,815 1.46 1M LIBOR+ Merrill Lynch Mortgage Investors Trust 22bps Series 2006-FF1, Floating Rate Note, 8/25/36 1,557,354 1,309,787 2.03 1M LIBOR+ Morgan Stanley ABS Capital I Inc Trust 79.5bps 2005-HE3, Floating Rate Note, 7/25/35 1,313,045 210,426 1.82 1M LIBOR+ Morgan Stanley ABS Capital I Inc Trust 39bps 2005-HE6, Floating Rate Note, 11/25/35 209,946 1,629,385 1.97 1M LIBOR+ Morgan Stanley ABS Capital I Inc Trust 73.5bps 2005-WMC1, Floating Rate Note, 1/25/35 1,634,859 3,108 1.94 1M LIBOR+ Morgan Stanley ABS Capital I Inc Trust 70.5bps 2005-WMC3, Floating Rate Note, 3/25/35 3,109 26,680 1.86 Morgan Stanley ABS Capital I, Inc. Trust 2005-NC2, Floating Rate Note, 3/25/35 26,685 183,440 2.02 1M LIBOR+ Morgan Stanley Home Equity Loan Trust 78bps 2005-1, Floating Rate Note, 12/25/34 184,157 953,569 1.52 1M LIBOR+ Morgan Stanley Home Equity Loan Trust 28bps 2006-2, Floating Rate Note, 2/25/36 946,986 327,852 1.43 1M LIBOR+ Morgan Stanley Structured Trust, Floating 19bps Rate Note, 6/25/37 327,462 277,193 1.84 1M LIBOR+ MOTOR 2015-1 Plc, Floating Rate Note, 60bps 6/27/22 (144A) 277,287 3,500,000 1.77 1M LIBOR+ Motor 2017-1 Plc, Floating Rate Note, 53bps 10/25/24 (144A) 3,502,720 85,428 Nations Equipment Finance Funding II LLC, 1.558%, 7/20/18 (144A) 85,393 759,212 Nations Equipment Finance Funding II LLC, 3.276%, 1/22/19 (144A) 759,393 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 31 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 3,354,105 Nations Equipment Finance Funding III LLC, 3.61%, 2/22/21 (144A) $ 3,364,520 900,000 3.60 Nationstar HECM Loan Trust 2016-2, Variable Rate Note, 6/25/26 (144A) 921,921 4,450,065 Nationstar HECM Loan Trust 2017-1, 1.9679%, 5/25/27 (144A) 4,450,999 4,400,000 2.04 Nationstar HECM Loan Trust 2017-2, Floating Rate Note, 9/25/27 (144A) 4,400,000 871,195 1.52 Nationstar Home Equity Loan Trust 2006-B REMICS, Floating Rate Note, 9/25/36 865,985 1,225,000 Navitas Equipment Receivables LLC 2015-1, 4.5%, 6/17/19 (144A) 1,237,024 2,277,325 Navitas Equipment Receivables LLC 2016-1, 2.2%, 6/15/21 (144A) 2,276,776 4,600,000 Navitas Equipment Receivables LLC 2016-1, 3.22%, 10/15/21 (144A) 4,610,599 571,974 1.93 1M LIBOR+ New Century Home Equity Loan Trust 70bps 2005-1, Floating Rate Note, 3/25/35 572,801 418,057 1.73 1M LIBOR+ New Century Home Equity Loan Trust 49bps 2005-3 REMICS, Floating Rate Note, 7/25/35 418,764 200,000 New Residential Advance Receivables Trust Advance Receivables Backed Notes, 2.5751%, 10/15/49 (144A) 198,515 7,250,000 2.93 1M LIBOR+ NextGear Floorplan Master Owner Trust, 170bps Floating Rate Note, 4/15/21 (144A) 7,391,358 5,000,000 2.33 1M LIBOR+ NextGear Floorplan Master Owner Trust, 110bps Floating Rate Note, 9/15/21 (144A) 5,007,243 53,327 1.58 1M LIBOR+ Nissan Auto Receivables 2015-C Owner 35bps Trust, Floating Rate Note, 11/15/18 53,333 604,186 1.58 1M LIBOR+ Nissan Auto Receivables 2016-A Owner 35bps Trust, Floating Rate Note, 2/15/19 604,495 522,244 1.53 1M LIBOR+ Nissan Auto Receivables 2016-B Owner 30bps Trust, Floating Rate Note, 4/15/19 522,559 2,700,000 1.29 1M LIBOR+ Nissan Auto Receivables 2017-A Owner 6bps Trust, Floating Rate Note, 1/15/20 2,699,999 6,059,000 1.54 1M LIBOR+ Nissan Master Owner Trust Receivables, 31bps Floating Rate Note, 4/15/21 6,068,221 223,319 2.02 1M LIBOR+ NovaStar Mortgage Funding Trust Series 39bps 2003-1, Floating Rate Note, 5/25/33 217,043 222,634 2.89 1M LIBOR+ NovaStar Mortgage Funding Trust Series 165bps 2004-4, Floating Rate Note, 3/25/35 222,989 11,070,819 1.91 1M LIBOR+ NovaStar Mortgage Funding Trust Series 67.5 bps 2005-3, Floating Rate Note, 1/25/36 11,049,531 3,843,666 1.70 1M LIBOR+ NovaStar Mortgage Funding Trust Series 23bps 2005-4, Floating Rate Note, 1/25/36 3,840,976 The accompanying notes are an integral part of these financial statements. 32 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 8,008,102 1.40 1M LIBOR+ NovaStar Mortgage Funding Trust Series 16bps 2006-1, Floating Rate Note, 5/25/36 $ 7,928,931 593,348 NYCTL 2016-A Trust, 1.47%, 11/10/29 (144A) 589,415 5,816,000 NYCTL 2017-A Trust, 1.87%, 11/10/30 (144A) 5,816,000 3,250,000 Ocwen Master Advance Receivables Trust, 2.4989%, 9/15/48 (144A) 3,251,631 4,452,000 Ocwen Master Advance Receivables Trust, 2.5207%, 8/17/48 (144A) 4,433,001 2,700,000 Ocwen Master Advance Receivables Trust, 3.1413%, 9/15/48 (144A) 2,701,351 521,588 OneMain Financial Issuance Trust 2014-2, 2.47%, 9/18/24 (144A) 522,183 6,650,000 2.04 1M LIBOR+ OneMain Financial Issuance Trust 2017-1, 80bps Floating Rate Note, 9/14/32 (144A) 6,662,230 3,000,000 Oportun Funding III LLC, 3.69%, 7/8/21 (144A) 3,028,402 960,555 2.04 1M LIBOR+ Option One Mortgage Loan Trust 2005-1, 66bps Floating Rate Note, 2/25/35 958,381 8,000,000 1.97 1M LIBOR+ Option One Mortgage Loan Trust 2005-3, 73.5bps Floating Rate Note, 8/25/35 7,996,602 29,594 Option One Mortgage Loan Trust 2007-FXD2, 5.9%, 3/25/37 (Step) 27,227 84,003 Orange Lake Timeshare Trust 2012-A, 4.87%, 3/10/27 (144A) 84,760 4,753,953 OSAT 2016-NPL1 Trust, 3.75%, 7/25/56 (Step) (144A) 4,790,930 2,261,439 Oscar US Funding Trust II, 1.86%, 10/15/19 (144A) 2,256,394 1,746,240 Oscar US Funding Trust IV, 2.53%, 7/15/20 (144A) 1,746,422 821,760 2.93 1M LIBOR+ Oscar US Funding Trust IV, Floating Rate 170bps Note, 7/15/20 (144A) 823,799 6,077,617 OSCAR US Funding Trust V, 2.31%, 11/15/19 (144A) 6,078,207 4,908,845 2.63 OSCAR US Funding Trust V, Floating Rate Note, 11/15/19 (144A) 4,927,258 483,310 OSCAR US Funding Trust VI LLC, 2.3%, 5/11/20 (144A) 483,116 3,189,846 2.03 1M LIBOR+ OSCAR US Funding Trust VI LLC, Floating 80bps Rate Note, 5/11/20 (144A) 3,192,037 2,700,000 1.89 1M LIBOR+ OSCAR US Funding Trust VII LLC, Floating 65bps Rate Note, 11/10/20 (144A) 2,699,997 856 1.76 1M LIBOR+ Park Place Securities Inc Asset-Backed 26bps Pass-Through Ctfs Ser 2005-WHQ4, Floating Rate Note, 9/25/35 856 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 33 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 227,672 1.98 1M LIBOR+ Park Place Securities, Inc. Asset-Backed 37bps Pass-Through Certificates Series 2005- WHQ4, Floating Rate Note, 9/25/35 $ 227,762 454,303 2.14 1M LIBOR+ People's Choice Home Loan Securities 90bps Trust Series 2004-2, Floating Rate Note, 10/25/34 455,722 2,290,000 1.83 1M LIBOR+ PFS Financing Corp., Floating Rate Note, 60bps 10/15/19 (144A) 2,287,572 1,700,000 2.08 1M LIBOR+ PFS Financing Corp., Floating Rate Note, 85bps 10/15/19 (144A) 1,699,999 4,000,000 2.43 1M LIBOR+ PFS Financing Corp., Floating Rate Note, 175bps 2/18/20 (144A) 4,014,770 1,250,000 2.98 1M LIBOR+ PFS Financing Corp., Floating Rate Note, 120bps 2/18/20 (144A) 1,252,615 2,600,000 1.81 1M LIBOR+ PFS Financing Corp., Floating Rate Note, 58bps 3/15/21 (144A) 2,604,419 2,000,000 2.18 1M LIBOR+ PFS Financing Corp., Floating Rate Note, 95bps 3/15/21 (144A) 2,001,446 1,350,000 1.85 1M LIBOR+ PFS Financing Corp., Floating Rate Note, 62bps 4/15/20 (144A) 1,352,659 6,700,000 1.83 1M LIBOR+ PFS Financing Corp., Floating Rate Note, 60bps 7/15/22 (144A) 6,699,330 946,493 1.91 1M LIBOR+ Popular ABS Mortgage Pass-Through Trust 45bps 2005-C, Floating Rate Note, 11/25/35 948,445 165,453 1.56 1M LIBOR+ Popular ABS Mortgage Pass-Through Trust 32bps 2006-A, Floating Rate Note, 2/25/36 165,282 1,618,549 Prestige Auto Receivables Trust 2016-2, 1.46%, 7/15/20 (144A) 1,615,681 2,872,103 Pretium Mortgage Credit Partners I 2016-NPL6 LLC, 3.5%, 10/27/31 (Step) (144A) 2,885,114 4,481,282 Pretium Mortgage Credit Partners I 2017-NPL3 LLC, 3.25%, 6/27/32 (Step) (144A) 4,475,911 8,123,584 Pretium Mortgage Credit Partners I 2017-NPL4 LLC, 3.25%, 8/27/32 (Step) (144A) 8,103,224 4,490,981 PRPM 2017-1 LLC, 4.25%, 1/25/22 (Step) (144A) 4,503,952 114,454 Purchasing Power Funding 2015-A LLC, 3.5%, 12/15/19 (144A) 114,457 1,086,253 1.90 1M LIBOR+ Quest Trust REMICS, Floating Rate Note, 66bps 3/25/34 (144A) 1,076,521 348,829 2.04 1M LIBOR+ RAAC Series 2005-RP3 Trust, Floating 80bps Rate Note, 5/25/39 (144A) 344,406 901,797 1.49 1M LIBOR+ RAAC Series 2006-RP2 Trust, Floating 25bps Rate Note, 2/25/37 (144A) 897,399 The accompanying notes are an integral part of these financial statements. 34 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 1,300,000 1.88 1M LIBOR+ RAMP Series 2005-EFC6 Trust, Floating 43bps Rate Note, 11/25/35 $ 1,299,034 7,350,000 1.74 1M LIBOR+ RAMP Series 2005-RS7 Trust, Floating 50bps Rate Note, 7/25/35 7,269,542 419,760 1.40 1M LIBOR+ RAMP Series 2006-EFC2 Trust, Floating 16bps Rate Note, 12/25/36 418,455 2,424,345 1.70 1M LIBOR+ RASC Series 2001-KS3 Trust, Floating 46bps Rate Note, 9/25/31 2,374,672 2,849,626 1.89 1M LIBOR+ RASC Series 2005-EMX4 Trust, Floating 66bps Rate Note, 11/25/35 2,858,988 3,792,166 1.85 1M LIBOR+ RASC Series 2005-KS10 Trust, Floating 41bps Rate Note, 11/25/35 3,792,386 817,816 1.64 1M LIBOR+ RASC Series 2005-KS11 Trust, Floating 40bps Rate Note, 12/25/35 817,916 1,169,181 1.88 1M LIBOR+ RASC Series 2005-KS2 Trust, Floating 64.5bps Rate Note, 3/25/35 1,169,744 265,949 1.67 1M LIBOR+ RASC Series 2005-KS9 Trust, Floating 43bps Rate Note, 10/25/35 265,958 905,614 RBSHD 2013-1 Trust, 7.6853%, 10/25/47 (Step) (144A) 907,580 5,196,687 RCO Mortgage LLC 2017-1, 3.375%, 8/25/22 (Step) (144A) 5,203,475 58,538 2.14 1M LIBOR+ Salomon Mortgage Loan Trust Series 90bps 2001-CB4, Floating Rate Note, 11/25/33 58,202 625,000 Santander Drive Auto Receivables Trust 2015-3, 2.74%, 1/15/21 629,517 507,025 2.06 1M LIBOR+ SASCO Mortgage Loan Trust 2005-GEL1, 82.5bps Floating Rate Note, 12/25/34 507,276 468,415 1.70 1M LIBOR+ Saxon Asset Securities Trust 2005-3, 46bps Floating Rate Note, 11/25/35 468,505 795,043 1.40 1M LIBOR+ Saxon Asset Securities Trust 2006-1, 32bps Floating Rate Note, 3/25/36 792,965 3,658,361 SCF Equipment Trust 2016-1 LLC, 3.62%, 11/20/21 (144A) 3,670,556 126,301 1.80 1M LIBOR+ Securitized Asset Backed Receivables 28bps LLC Trust 2006-WM1, Floating Rate Note, 12/25/35 126,404 1,503,798 1.59 1M LIBOR+ Securitized Term Auto Receivables Trust 35bps 2016-1, Floating Rate Note, 11/26/18 (144A) 1,504,399 4,605,748 1.54 1M LIBOR+ Securitized Term Auto Receivables Trust 30bps 2017-1, Floating Rate Note, 4/25/19 (144A) 4,606,151 7,500,000 1.64 1M LIBOR+ Securitized Term Auto Receivables Trust 20bps 2017-2, Floating Rate Note, 1/27/20 (144A) 7,500,000 658,782 Sierra Auto Receivables Securitization Trust 2016-1, 2.85%, 1/18/22 (144A) 660,477 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 35 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 181,524 2.05 Sierra Timeshare 2014-2 Receivables Funding LLC, Floating Rate Note, 6/20/31 (144A) $ 181,217 1,276,902 Skopos Auto Receivables Trust 2015-1, 3.1%, 12/15/23 (144A) 1,277,345 2,700,000 Skopos Auto Receivables Trust 2015-1, 5.43%, 12/15/23 (144A) 2,720,521 147,405 Skopos Auto Receivables Trust 2015-2, 3.55%, 2/17/20 (144A) 147,436 4,702,474 Sofi Consumer Loan Program 2017-1 LLC, 3.28%, 1/26/26 (144A) 4,764,998 1,744,430 2.49 1M LIBOR+ SoFi Professional Loan Program 2014-B 125bps LLC, Floating Rate Note, 8/25/32 (144A) 1,765,041 2,756,020 2.28 1M LIBOR+ SoFi Professional Loan Program 2015-B 105bps LLC, Floating Rate Note, 4/25/35 (144A) 2,791,637 2,963,990 2.29 1M LIBOR+ SoFi Professional Loan Program 2015-C 105bps LLC, Floating Rate Note, 8/27/35 (144A) 2,988,844 1,102,582 2.98 1M LIBOR+ Sofi Professional Loan Program 2016-A 175bps LLC, Floating Rate Note, 8/25/36 (144A) 1,140,620 1,034,746 2.43 1M LIBOR+ Sofi Professional Loan Program 2016-B 120bps LLC, Floating Rate Note, 6/25/33 (144A) 1,051,295 486,425 2.33 1M LIBOR+ SoFi Professional Loan Program 2016-C 110bps LLC, Floating Rate Note, 10/25/36 (144A) 493,568 2,845,506 2.19 1M LIBOR+ SoFi Professional Loan Program 2016-D 95bps LLC, Floating Rate Note, 1/25/39 (144A) 2,873,577 10,158,665 2.08 1M LIBOR+ Sofi Professional Loan Program 2016-E 85bps LLC, Floating Rate Note, 7/25/39 (144A) 10,243,994 2,242,974 1.94 1M LIBOR+ SoFi Professional Loan Program 2017-A 70bps LLC, Floating Rate Note, 3/26/40 (144A) 2,255,399 2,410,607 Sofi Professional Loan Program 2017-B LLC, 1.83%, 5/25/40 (144A) 2,411,297 2,539,996 1.84 1M LIBOR+ Sofi Professional Loan Program 2017-C 60bps LLC, Floating Rate Note, 7/25/40 (144A) 2,542,262 4,127,330 SoFi Professional Loan Program 2017-D LLC, 1.72%, 9/25/40 (144A) 4,123,081 88 1.95 1M LIBOR+ Soundview Home Loan Trust 2005-DO1, 72bps Floating Rate Note, 5/25/35 88 170,562 1.50 1M LIBOR+ Soundview Home Loan Trust 2005-OPT4, 26bps Floating Rate Note, 12/25/35 170,468 2,706,347 1.54 1M LIBOR+ Specialty Underwriting & Residential 30bps Finance Trust Series 2006-BC1, Floating Rate Note, 12/25/36 2,705,619 4,700,000 SPS Servicer Advance Receivables Trust Advance Receivables Backed Notes 2016-T1, 2.53%, 11/16/48 (144A) 4,662,099 1,285,000 SPS Servicer Advance Receivables Trust Advance Receivables Backed Notes 2016-T1, 3.32%, 11/16/48 (144A) 1,278,037 The accompanying notes are an integral part of these financial statements. 36 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 3,381,470 2.00 1M LIBOR+ Structured Asset Investment Loan Trust 76bps 2003-BC1, Floating Rate Note, 1/25/33 $ 3,341,629 347,382 2.29 1M LIBOR+ Structured Asset Investment Loan Trust 106bps 2004-10, Floating Rate Note, 11/25/34 350,406 206,428 2.13 1M LIBOR+ Structured Asset Investment Loan Trust 90bps 2004-11, Floating Rate Note, 1/25/35 206,877 1,236,398 2.28 1M LIBOR+ Structured Asset Investment Loan Trust 104bps 2004-BNC2, Floating Rate Note, 12/25/34 1,238,942 508,396 1.95 1M LIBOR+ Structured Asset Investment Loan Trust 70.5bps 2005-6, Floating Rate Note, 7/25/35 508,970 717,012 1.94 1M LIBOR+ Structured Asset Investment Loan Trust 72bps 2005-HE1, Floating Rate Note, 7/25/35 718,154 5,572,511 1.96 1M LIBOR+ Structured Asset Investment Loan Trust 20bps 2005-HE3, Floating Rate Note, 9/25/35 5,555,764 325,002 1.44 1M LIBOR+ Structured Asset Investment Loan Trust 66bps 2006-1, Floating Rate Note, 1/25/36 324,734 649,751 1.89 1M LIBOR+ Structured Asset Securities Corp 2005-WF1, 15bps Floating Rate Note, 2/25/35 651,161 830,187 1.39 1M LIBOR+ Structured Asset Securities Corp Mortgage 18bps Loan Trust 2006-EQ1, Floating Rate Note, 7/25/36 (144A) 828,537 6,063,351 1.42 1M LIBOR+ Structured Asset Securities Corp Mortgage 14bps Loan Trust 2006-OPT1, Floating Rate Note, 4/25/36 5,955,917 705,762 1.38 1M LIBOR+ Structured Asset Securities Corp Mortgage 30bps Loan Trust 2007-BC3, Floating Rate Note, 5/25/47 705,198 4,023,386 1.53 1M LIBOR+ Structured Asset Securities Corp Mortgage 150bps Loan Trust 2007-TC1, Floating Rate Note, 4/25/31 (144A) 3,884,340 927,357 2.74 1M LIBOR+ Structured Asset Securities Corp Mortgage 43bps Pass-Through Ctfs Ser 2003-BC2, Floating Rate Note, 3/25/33 919,675 157,679 1.67 1M LIBOR+ Structured Asset Securities Corp Trust 43bps 2005-AR1, Floating Rate Note, 9/25/35 157,943 1,172,220 Sunset Mortgage Loan Co 2015-NPL1 LLC, 4.4586%, 9/16/45 (Step) (144A) 1,174,208 182,879 SVO 2012-A VOI Mortgage LLC, 2.0%, 9/20/29 (144A) 180,861 700,000 Synchrony Credit Card Master Note Trust, 1.69%, 3/15/21 699,266 1,446,072 Tax Ease Funding LLC Series 16-1A, 3.13%, 6/15/28 1,454,845 4,108,103 TCF Auto Receivables Owner Trust 2016-PT1, 1.93%, 6/15/22 (144A) 4,106,941 205,083 2.81 1M LIBOR+ Terwin Mortgage Trust 2005-1SL, Floating 157.5bps Rate Note, 2/25/35 (144A) 202,748 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 37 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 3,070,302 1.62 1M LIBOR+ Terwin Mortgage Trust 2006-1, Floating 38bps Rate Note, 1/25/37 (144A) $ 3,078,346 4,295,784 1.47 1M LIBOR+ Terwin Mortgage Trust 2006-3, Floating 23bps Rate Note, 4/25/37 (144A) 4,277,358 112,936 Tidewater Auto Receivables Trust 2016-A, 2.3%, 9/15/19 (144A) 112,915 3,000,000 Tidewater Sales Finance Master Trust Series 2017-A, 4.55%, 5/15/21 (144A) 2,998,076 2,150,000 1.30 1M LIBOR+ Toyota Auto Receivables 2017-A Owner 7bps Trust, Floating Rate Note, 9/16/19 2,150,398 6,670,000 1.31 Toyota Auto Receivables 2017-C Owner Trust, Floating Rate Note, 7/15/20 6,670,098 5,423,000 2.18 1M LIBOR+ Trafigura Securitisation Finance Plc 2014-1, 95bps Floating Rate Note, 4/16/18 (144A) 5,423,824 1,750,000 3.48 1M LIBOR+ Trafigura Securitisation Finance Plc 2014-1, 225bps Floating Rate Note, 4/16/18 (144A) 1,750,598 8,000,000 2.08 1M LIBOR+ Trafigura Securitisation Finance Plc 2017-1, 85bps Floating Rate Note, 12/15/20 (144A) 8,022,584 2,000,000 2.93 1M LIBOR+ Trafigura Securitisation Finance Plc 2017-1, 170bps Floating Rate Note, 12/15/20 (144A) 2,011,168 8,000,000 1.95 1M LIBOR+ Trillium Credit Card Trust II, Floating Rate 72bps Note, 5/26/21 (144A) 8,030,326 801,461 2.94 1M LIBOR+ Truman Capital Mortgage Loan Trust, 170bps Floating Rate Note, 1/25/34 799,836 695,252 1.49 1M LIBOR+ Truman Capital Mortgage Loan Trust, 26bps Floating Rate Note, 3/25/36 (144A) 670,700 4,500,000 United Auto Credit Securitization Trust 2016-1, 7.1%, 5/16/22 (144A) 4,640,316 141,490 United Auto Credit Securitization Trust 2016-2, 1.67%, 9/10/18 (144A) 141,493 5,000,000 United Auto Credit Securitization Trust 2016-2, 2.2%, 5/10/19 (144A) 4,999,317 6,400,000 United Auto Credit Securitization Trust 2017-1, 2.4%, 11/12/19 (144A) 6,391,427 4,260,000 United Auto Credit Securitization Trust 2017-1, 2.71%, 1/10/22 (144A) 4,251,854 2,728,186 Upstart Securitization Trust 2017-1, 2.639%, 6/20/24 (144A) 2,726,787 4,145,964 US Residential Opportunity Fund IV Trust 2016-1, 3.4747%, 7/27/36 (Step) (144A) 4,156,003 6,113,121 VOLT LIV LLC, 3.5%, 2/25/47 (Step) (144A) 6,150,691 3,867,059 VOLT LVIII LLC, 3.375%, 5/28/47 (Step) (144A) 3,891,225 3,348,601 VOLT LX LLC, 3.25%, 4/25/59 (Step) (144A) 3,361,457 85,903 VOLT XIX LLC, 3.875%, 4/26/55 (Step) (144A) 85,934 The accompanying notes are an integral part of these financial statements. 38 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 3,322,463 VOLT XXV LLC, 3.5%, 6/26/45 (Step) (144A) $ 3,328,532 3,548,147 VOLT XXXVIII LLC, 3.875%, 9/25/45 (Step) (144A) 3,561,591 973,000 1.74 1M LIBOR+ Wells Fargo Dealer Floorplan Master Note 50bps Trust, Floating Rate Note, 1/20/20 974,047 1,231,328 1.49 Wells Fargo Home Equity Asset-Backed Securities 2006-1 Trust REMICS, Floating Rate Note, 7/25/36 1,227,355 420,565 Westgate Resorts 2016-1 LLC, 3.5%, 12/20/28 (144A) 424,226 7,615,320 Westgate Resorts 2017-1 LLC, 3.05%, 12/20/30 (144A) 7,635,763 1,400,000 Westlake Automobile Receivables Trust 2015-3, 3.05%, 5/17/21 (144A) 1,407,332 8,455,000 Westlake Automobile Receivables Trust 2016-1, 4.55%, 9/15/21 (144A) 8,610,794 438,231 2.28 Westlake Automobile Receivables Trust 2016-1, Floating Rate Note, 1/15/19 (144A) 438,591 1,529,921 Westlake Automobile Receivables Trust 2016-3, 1.42%, 10/15/19 (144A) 1,529,126 4,400,000 Westlake Automobile Receivables Trust 2017-1, 1.78%, 4/15/20 (144A) 4,402,375 6,200,000 1.58 1M LIBOR+ Westlake Automobile Receivables Trust 35bps 2017-2, Floating Rate Note, 7/15/20 (144A) 6,200,076 19,438 1.51 1M LIBOR+ Wilshire Mortgage Loan Trust, Floating 28bps Rate Note, 5/25/28 19,199 3,454,000 1.71 1M LIBOR+ World Financial Network Credit Card 48bps Master Trust, Floating Rate Note, 2/15/22 3,459,977 108,870 1.63 1M LIBOR+ World Omni Auto Receivables Trust 2015-B, 40bps Floating Rate Note, 7/15/19 108,889 7,400,000 1.37 1M LIBOR+ World Omni Auto Receivables Trust 2017-A, 14bps Floating Rate Note, 8/17/20 7,401,459 8,200,000 1.33 1M LIBOR+ World Omni Auto Receivables Trust 2017-B, 10bps Floating Rate Note, 2/16/21 8,199,357 -------------- $1,012,281,839 -------------- Total Banks $1,012,281,839 -------------------------------------------------------------------------------------------------------------- DIVERSIFIED FINANCIALS -- 1.3% Other Diversified Financial Services -- 0.1% 1,520,826 1.43 1M LIBOR+ 321 Henderson Receivables I LLC, Floating 20bps Rate Note, 6/15/41 (144A) $ 1,483,184 1,038,608 2.02 1M LIBOR+ Countrywide Asset-Backed Certificates, 78bps Floating Rate Note, 5/25/36 1,040,089 1,394,977 1.54 1M LIBOR+ Mastr Specialized Loan Trust, Floating 30bps Rate Note, 1/25/36 (144A) 1,376,891 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 39 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Other Diversified Financial Services -- (continued) 792,117 Sierra Timeshare 2013-1 Receivables Funding LLC, 2.39%, 11/20/29 (144A) $ 792,052 208,871 TAL Advantage V LLC, 1.7%, 5/20/39 (144A) 208,513 -------------- $ 4,900,729 -------------------------------------------------------------------------------------------------------------- Specialized Finance -- 0.1% 3,305,000 1.69 1M LIBOR+ Wells Fargo Dealer Floorplan Master Note 45bps Trust, Floating Rate Note, 10/21/19 $ 3,305,661 -------------------------------------------------------------------------------------------------------------- Consumer Finance -- 1.1% 3,300,000 1.52 1M LIBOR+ American Express Credit Account Master 29bps Trust, Floating Rate Note, 5/15/20 $ 3,300,398 2,770,000 1.65 1M LIBOR+ American Express Credit Account Master 42bps Trust, Floating Rate Note, 5/17/21 2,780,802 2,100,000 2.03 1M LIBOR+ American Express Credit Account Secured 80bps Note Trust 2012-4, Floating Rate Note, 5/15/20 (144A) 2,100,587 6,600,000 1.68 1M LIBOR+ Capital One Multi-Asset Execution Trust, 45bps Floating Rate Note, 2/15/22 6,634,900 12,000,000 Chase Issuance Trust, 1.38%, 11/15/19 12,000,865 4,045,000 1.60 1M LIBOR+ Chase Issuance Trust, Floating Rate 37bps Note, 4/15/21 4,062,796 7,740,000 1.64 1M LIBOR+ Chase Issuance Trust, Floating Rate 41bps Note, 5/17/21 7,780,181 124,259 CPS Auto Receivables Trust 2013-B, 1.82%, 9/15/20 (144A) 124,183 1,450,000 First Investors Auto Owner Trust 2015-1, 3.59%, 1/18/22 (144A) 1,462,860 -------------- $ 40,247,572 -------------------------------------------------------------------------------------------------------------- Asset Management & Custody Banks -- 0.0%+ 505,964 Engs Commercial Finance Trust 2015-1, 2.31%, 10/22/21 (144A) $ 504,771 -------------- Total Diversified Financials $ 48,958,733 -------------------------------------------------------------------------------------------------------------- REAL ESTATE -- 0.1% Diversified Real Estate Activities -- 0.1% 3,790,000 1.54 1M LIBOR+ HSI Asset Securitization Corp Trust 30bps 2006-OPT1, Floating Rate Note, 12/25/35 $ 3,772,103 13,222 1.43 1M LIBOR+ HSI Asset Securitization Corp. Trust 19bps 2006-OPT1, Floating Rate Note, 12/25/35 13,221 -------------- $ 3,785,324 -------------- Total Real Estate $ 3,785,324 -------------------------------------------------------------------------------------------------------------- TOTAL ASSET BACKED SECURITIES (Cost $1,116,586,752) $1,119,491,818 -------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 40 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- COLLATERALIZED MORTGAGE OBLIGATIONS -- 24.1% ENERGY -- 0.3% Oil & Gas Exploration & Production -- 0.3% 2,750,000 2.93 1M LIBOR+ Arbor Realty Commercial Real Estate 170bps Notes 2016-FL1, Ltd., Floating Rate Note, 9/15/26 (144A) $ 2,771,621 3,800,100 3.48 1M LIBOR+ Oaktown Re, Ltd., Floating Rate Note, 225bps 4/25/27 (144A) 3,934,274 4,719,677 2.19 1M LIBOR+ RAIT 2017-FL7 Trust, Floating Rate Note, 95bps 6/15/37 (144A) 4,721,639 -------------- $ 11,427,534 -------------- Total Energy $ 11,427,534 -------------------------------------------------------------------------------------------------------------- CAPITAL GOODS -- 0.1% Construction & Engineering -- 0.0%+ 867,674 3.68 1M LIBOR+ Velocity Commercial Capital Loan Trust 245bps 2016-1, Floating Rate Note, 4/25/46 (144A) $ 879,604 -------------------------------------------------------------------------------------------------------------- Industrial Conglomerates -- 0.1% 2,965,634 VSD 2017-Plt1 LLC, 3.6%, 12/25/43 (144A) $ 2,967,320 -------------- Total Capital Goods $ 3,846,924 -------------------------------------------------------------------------------------------------------------- BANKS -- 19.3% Diversified Banks -- 0.0%+ 1,750,000 3.98 1M LIBOR+ Bancorp Commercial Mortgage 275bps 2016-CRE1 Trust, Floating Rate Note, 11/15/33 (144A) $ 1,749,167 -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- 19.3% 11,500,000 N/A 1M LIBOR+ 280 Park Avenue 2017-280P Mortgage 125bps Trust, Floating Rate Note, 9/15/34 (144A) $ 11,524,863 11,500,000 2.08 1M LIBOR+ A10 Term Asset Financing 2017-1 LLC, 85bps Floating Rate Note, 3/15/36 (144A) 11,500,000 6,534 2.02 1M LIBOR+ Adjustable Rate Mortgage Trust 2005-2, 78bps Floating Rate Note, 6/25/35 6,532 499,675 1.80 1M LIBOR+ Adjustable Rate Mortgage Trust 2005-5, 28bps Floating Rate Note, 9/25/35 497,311 1,471,339 3.00 Agate Bay Mortgage Trust 2014-3, Variable Rate Note, 11/25/44 (144A) 1,483,294 965,849 1.82 1M LIBOR+ Alternative Loan Trust 2004-6CB, Floating 58bps Rate Note, 4/25/34 970,483 545,478 2.14 1M LIBOR+ Alternative Loan Trust 2004-J13, Floating 90bps Rate Note, 2/25/35 540,405 3,300,000 3.48 1M LIBOR+ AMSR 2016-SFR1 Trust, Floating Rate 225bps Note, 11/17/33 (144A) 3,357,769 2,700,000 2.53 1M LIBOR+ Arbor Realty Commercial Real Estate 130bps Notes 2017-FL1, Ltd., Floating Rate Note, 4/15/27 (144A) 2,725,419 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 41 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 1,550,503 3.51 ASG Resecuritization Trust 2012-1, Variable Rate Note, 4/28/36 (144A) $ 1,548,967 8,213,000 3.43 1M LIBOR+ BAMLL Commercial Mortgage Securities 220bps Trust 2014-FL1, Floating Rate Note, 12/17/31 (144A) 8,227,169 4,320,000 2.34 1M LIBOR+ BAMLL Commercial Mortgage Securities 110bps Trust 2014-ICTS, Floating Rate Note, 6/15/28 (144A) (e) 4,322,551 5,500,000 4.23 1M LIBOR+ BAMLL Commercial Mortgage Securities 300bps Trust 2016-ASHF, Floating Rate Note, 3/15/28 (144A) 5,590,914 1,460,266 0.00 BAMLL Re-REMIC Trust 2014-FRR5, Variable Rate Note, 3/29/45 (144A) 1,456,605 2,617,382 5.88 Banc of America Commercial Mortgage Trust 2006-1, Variable Rate Note, 9/10/45 2,615,981 1,559,575 6.47 Banc of America Commercial Mortgage Trust 2008-1, Variable Rate Note, 2/10/51 1,562,336 438,476 1.86 1M LIBOR+ Banc of America Funding 2005-A Trust, 31bps Floating Rate Note, 2/20/35 439,960 172,463 3.29 Banc of America Mortgage 2004-I Trust, Variable Rate Note, 10/25/34 171,760 2,200,000 2.08 1M LIBOR+ Bancorp Commercial Mortgage 2017-CRE2 85bps Trust, Floating Rate Note, 8/15/32 (144A) 2,199,998 3,345,246 3.23 1M LIBOR+ Bayview Opportunity Master Fund IIIb Trust 200bps 2017-CRT2, Floating Rate Note, 11/25/27 (144A) 3,344,705 3,758,793 2.98 1M LIBOR+ Bayview Opportunity Master Fund IVb Trust 175bps 2016-CRT1, Floating Rate Note, 10/27/27 (144A) 3,758,666 3,037,314 3.39 1M LIBOR+ Bayview Opportunity Master Fund IVb Trust 215bps 2017-CRT1, Floating Rate Note, 10/25/28 (144A) 3,041,731 3,150,000 3.24 1M LIBOR+ BBCMS Trust 2015-SLP, Floating Rate Note, 200bps 2/15/28 (144A) 3,150,877 2,967,197 1.46 1M LIBOR+ BCAP LLC 2012-RR4 Trust, Floating Rate 23bps Note, 6/26/47 (144A) 2,938,941 383,307 2.08 Bear Stearns ALT-A Trust 2004-11, Floating Rate Note, 11/25/34 380,954 1,031,262 1.94 Bear Stearns ALT-A Trust 2004-12, Floating Rate Note, 1/25/35 1,010,881 2,313,848 2.08 1M LIBOR+ Bear Stearns ALT-A Trust 2004-12, Floating 84bps Rate Note, 1/25/35 2,281,832 1,468,824 2.08 1M LIBOR+ Bear Stearns ALT-A Trust 2004-12, Floating 84bps Rate Note, 1/25/35 1,453,457 879,731 1.98 Bear Stearns ALT-A Trust 2004-13, Floating Rate Note, 11/25/34 879,831 1,881,984 1.84 1M LIBOR+ Bear Stearns ALT-A Trust 2004-4, Floating 60bps Rate Note, 6/25/34 1,877,887 The accompanying notes are an integral part of these financial statements. 42 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 328,097 1.74 Bear Stearns ALT-A Trust 2005-2, Floating Rate Note, 3/25/35 $ 325,911 207,242 3.67 Bear Stearns Mortgage Securities, Inc., Floating Rate Note, 6/25/30 212,810 11,664 5.74 1M LIBOR+ Bellemeade Re II, Ltd., Floating Rate Note, 450bps 4/25/26 (144A) 11,737 4,100,000 3.19 1M LIBOR+ BHMS 2014-ATLS Mortgage Trust REMICS, 195bps Floating Rate Note, 7/8/33 (144A) 4,119,984 7,000,000 2.38 1M LIBOR+ BX Trust 2017-APPL, Floating Rate Note, 115bps 7/15/34 (144A) 7,004,325 7,900,000 2.43 1M LIBOR+ BX Trust 2017-SLCT, Floating Rate Note, 120bps 7/15/34 (144A) 7,897,452 3,823,000 4.08 1M LIBOR+ BXHTL 2015-JWRZ Mortgage Trust, Floating 285bps Rate Note, 5/15/29 (144A) 3,825,974 2,315,000 2.25 3M LIBOR+ Canyon Capital CLO 2014-2, Ltd., Floating 95bps Rate Note, 4/15/29 (144A) 2,315,000 1,650,000 2.11 3M LIBOR+ Canyon Capital CLO 2015-1, Ltd., Floating 95bps Rate Note, 4/15/27 (144A) 1,650,000 3,500,000 2.00 3M LIBOR+ Cent CDO 14, Ltd., Floating Rate Note, 70bps 4/15/21 (144A) 3,357,669 4,243,671 2.56 3M LIBOR+ Cent CLO, Floating Rate Note, 8/1/24 125bps (144A) 4,244,440 7,200,000 3.38 1M LIBOR+ CFCRE 2015-RUM Mortgage Trust, Floating 215bps Rate Note, 7/15/30 (144A) 7,077,172 1,000,000 5.83 1M LIBOR+ CFCRE 2015-RUM Mortgage Trust, Floating 460bps Rate Note, 7/15/30 (144A) 976,576 2,932,150 3.09 1M LIBOR+ CG-CCRE Commercial Mortgage Trust 185.4bps 2014-FL2 REMICS, Floating Rate Note, 11/15/31 (144A) 2,933,318 4,900,000 2.33 1M LIBOR+ CGDB Commercial Mortgage Trust 110bps 2017-BIO, Floating Rate Note, 5/15/30 (144A) 4,903,059 10,300,000 2.20 1M LIBOR+ CGDBB Commercial Mortgage Trust 97bps 2017-BIOC, Floating Rate Note, 7/15/28 (144A) (e) 10,299,992 5,700,000 N/A 1M LIBOR+ CGMS Commercial Mortgage Trust 130bps 2017-MDDR, Floating Rate Note, 7/15/30 (144A) 5,699,994 370,093 4.33 1M LIBOR+ CGWF Commercial Mortgage Trust 310bps 2013-RKWH REMICS, Floating Rate Note, 11/15/30 (144A) 369,438 83,075 1.99 Chevy Chase Funding LLC Mortgage-Backed Certificates Series 2004-1, Floating Rate Note, 1/25/35 (144A) 79,438 33,219 1.54 Chevy Chase Funding LLC Mortgage-Backed Certificates Series 2004-3, Floating Rate Note, 8/25/35 (144A) 32,700 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 43 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 221,852 1.74 CHL Mortgage Pass-Through Trust 2003-15 REMICS, Floating Rate Note, 6/25/18 $ 220,184 3,062,500 N/A 3M LIBOR+ CIFC Funding 2013-I, Ltd., Floating Rate 85bps Note, 7/16/30 (144A) 3,062,019 1,812,811 3.24 1M LIBOR+ CIM Trust 2015-4AG, Floating Rate Note, 200bps 11/25/57 (144A) 1,813,389 3,296 Citicorp Mortgage Securities REMIC Pass- Through Certificates Trust Series 2005-4, 5.0%, 7/25/20 3,366 319,711 6.34 Citigroup Commercial Mortgage Trust 2008-C7, Variable Rate Note, 12/10/49 319,588 1,500,000 4.53 1M LIBOR+ Citigroup Commercial Mortgage Trust 330bps 2015-SHP2, Floating Rate Note, 7/15/27 (144A) 1,516,912 5,400,000 3.33 1M LIBOR+ Citigroup Commercial Mortgage Trust 210bps 2015-SSHP REMICS, Floating Rate Note, 9/15/27 (144A) 5,367,287 305,156 Citigroup Mortgage Loan Trust 2010-4 REMICS, 5.0%, 10/25/35 (144A) 307,788 6,700,000 2.33 1M LIBOR+ CLNS Trust 2017-IKPR, Floating Rate Note, 110bps 6/11/32 (144A) 6,695,854 7,668,000 2.58 1M LIBOR+ Cold Storage Trust 2017-ICE3, Floating Rate 135bps Note, 4/15/24 (144A) 7,717,287 1,500,000 3.33 1M LIBOR+ Cold Storage Trust 2017-ICE3, Floating Rate 210bps Note, 4/15/24 (144A) 1,508,432 3,900,000 3.08 1M LIBOR+ Colony American Homes 2014-1, Floating 185bps Rate Note, 5/19/31 (144A) 3,914,299 1,385,566 3.58 1M LIBOR+ Colony American Homes 2014-2 REMICS, 235bps Floating Rate Note, 7/17/31 (144A) 1,390,504 1,630,078 4.43 1M LIBOR+ Colony American Homes 2014-2 REMICS, 320bps Floating Rate Note, 7/17/31 (144A) 1,635,792 639,834 3.18 1M LIBOR+ Colony Mortgage Capital Series 2015-FL3, 195bps Ltd., Floating Rate Note, 9/5/32 (144A) 639,829 1,150,000 3.88 1M LIBOR+ Colony Starwood Homes 2016-1 Trust, 265bps Floating Rate Note, 7/17/33 (144A) 1,186,552 4,840,000 2.98 1M LIBOR+ Colony Starwood Homes 2016-2 Trust, 175bps Floating Rate Note, 12/19/33 (144A) 4,845,755 5,600,000 3.68 1M LIBOR+ COMM 2014-FL4 Mortgage Trust REMICS, 245bps Floating Rate Note, 7/15/31 (144A) 5,552,672 5,470,000 3.38 1M LIBOR+ COMM 2014-FL5 Mortgage Trust, Floating 215bps Rate Note, 10/15/31 (144A) 5,432,914 6,980,000 2.04 1M LIBOR+ COMM 2014-PAT Mortgage Trust REMICS, 80bps Floating Rate Note, 8/13/27 (144A) 6,982,183 2,722,000 2.83 1M LIBOR+ COMM 2014-PAT Mortgage Trust, Floating 165bps Rate Note, 8/13/27 (144A) 2,685,848 7,340,000 2.84 1M LIBOR+ COMM 2014-TWC Mortgage Trust, Floating 160bps Rate Note, 2/13/32 (144A) 7,368,247 The accompanying notes are an integral part of these financial statements. 44 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 4,500,000 3.54 1M LIBOR+ COMM 2016-SAVA Mortgage Trust, Floating 230bps Rate Note, 10/15/34 (144A) $ 4,542,161 5,713,000 2.19 1M LIBOR+ COMM 2017-DLTA Mortgage Trust, Floating 94bps Rate Note, 8/13/32 5,677,294 4,000,000 3.88 1M LIBOR+ Cosmopolitan Hotel Trust 2016-COSMO, 265bps Floating Rate Note, 11/15/33 (144A) 4,017,474 439,864 2.82 3M LIBOR+ Crown Point CLO, Ltd., Floating Rate Note, 150bps 11/21/22 (144A) 439,905 234,727 1.98 1M LIBOR+ CSFB Mortgage-Backed Pass-Through 74bps Certificates Series 2004-AR5, Floating Rate Note, 6/25/34 230,241 2,400,000 3.48 1M LIBOR+ CSMC 2015-TWNI Trust, Floating Rate 225bps Note, 3/15/28 (144A) 2,400,584 2,563,935 2.50 CSMC Series 2013-14R REMICS, Variable Rate Note, 10/27/37 (144A) 2,617,353 3,126,852 3.00 CSMC Trust 2014-OAK1, Variable Rate Note, 11/25/44 (144A) 3,158,121 1,576,967 4.00 CSMC Trust 2014-SAF1 REMICS, Variable Rate Note, 3/25/44 (144A) 1,592,860 5,900,294 3.00 CSMC Trust 2014-WIN2, Variable Rate Note, 10/25/44 (144A) 5,904,093 3,825,142 3.50 CSMC Trust 2015-3, Variable Rate Note, 3/25/45 (144A) 3,892,082 3,500,000 3.08 1M LIBOR+ CSMC Trust 2015-DEAL, Floating Rate 185bps Note, 4/16/29 (144A) 3,502,189 9,250,000 1.93 1M LIBOR+ DBCG 2017-BBG Mortgage Trust, Floating 70bps Rate Note, 6/15/34 (144A) 9,258,642 2,300,000 N/A 3M LIBOR+ Deer Creek Clo, Ltd. 2017-1, Floating Rate 100bps Note, 10/20/30 (144A) 2,300,000 3,928,131 1.78 1M LIBOR+ Fannie Mae Connecticut Avenue Securities, 55bps Floating Rate Note, 1/25/30 3,926,567 6,226,730 2.18 1M LIBOR+ Fannie Mae Connecticut Avenue Securities, 95bps Floating Rate Note, 10/25/29 6,256,839 3,452,291 2.08 1M LIBOR+ Fannie Mae Connecticut Avenue Securities, 85bps Floating Rate Note, 11/25/29 3,462,077 1,701,777 2.54 1M LIBOR+ Fannie Mae Connecticut Avenue Securities, 130bps Floating Rate Note, 4/25/29 1,710,084 4,024,545 2.53 1M LIBOR+ Fannie Mae Connecticut Avenue Securities, 130bps Floating Rate Note, 7/25/29 4,062,834 3,350,741 2.38 1M LIBOR+ Fannie Mae Connecticut Avenue Securities, 115bps Floating Rate Note, 9/25/29 3,374,479 2,793,224 3.00 FirstKey Mortgage Trust 2014-1 REMICS, Variable Rate Note, 11/25/44 (144A) 2,804,136 2,930,131 2.73 1M LIBOR+ FORT CRE 2016-1 LLC, Floating Rate Note, 150bps 5/21/36 (144A) 2,933,414 39,352 3.89 1M LIBOR+ Freddie Mac Structured Agency Credit Risk 265bps Debt Notes, Floating Rate Note, 10/25/24 39,497 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 45 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 6,355,982 2.43 1M LIBOR+ Freddie Mac Structured Agency Credit Risk 120bps Debt Notes, Floating Rate Note, 10/25/29 $ 6,428,496 1,717,903 2.03 1M LIBOR+ Freddie Mac Structured Agency Credit Risk 80bps Debt Notes, Floating Rate Note, 12/25/29 1,721,682 1,060,117 2.03 1M LIBOR+ Freddie Mac Structured Agency Credit Risk 80bps Debt Notes, Floating Rate Note, 4/25/29 1,060,580 1,091,819 2.34 1M LIBOR+ Freddie Mac Structured Agency Credit Risk 110bps Debt Notes, Floating Rate Note, 5/25/25 1,092,338 3,822,754 2.44 1M LIBOR+ Freddie Mac Structured Agency Credit Risk 120bps Debt Notes, Floating Rate Note, 8/25/29 3,854,091 5,000,000 5.54 FREMF Mortgage Trust 2010-K6, Variable Rate Note, 12/25/46 (144A) 5,312,272 7,645,000 3.68 FREMF Mortgage Trust 2012-K711, Variable Rate Note, 8/25/45 (144A) 7,796,653 9,500,000 3.48 FREMF Mortgage Trust 2013-K712, Variable Rate Note, 5/25/45 (144A) 9,665,263 333,301 2.53 1M LIBOR+ GAHR Commercial Mortgage Trust 130bps 2015-NRF, Floating Rate Note, 12/15/34 (144A) 332,907 398,928 Global Mortgage Securitization, Ltd., 5.25%, 4/25/32 (144A) 393,957 157,767 1.56 1M LIBOR+ Global Mortgage Securitization, Ltd., 32bps Floating Rate Note, 11/25/32 (144A) 149,612 2,431,092 1.51 1M LIBOR+ Global Mortgage Securitization, Ltd., 27bps Floating Rate Note, 4/25/32 (144A) 2,342,203 1,391,650 2.02 3M LIBOR+ Gosforth Funding 2016-1 Plc, Floating 70bps Rate Note, 2/15/58 (144A) 1,395,572 1,873,371 1.58 1M LIBOR+ Government National Mortgage 35bps Association, Floating Rate Note, 2/16/33 1,879,802 3,350,000 2.78 1M LIBOR+ GP Portfolio Trust 2014-GGP, Floating 155bps Rate Note, 2/15/27 (144A) 3,355,252 9,750,000 2.56 1M LIBOR+ Great Wolf Trust 2017-WOLF, Floating Rate 132bps Note, 9/15/34 (144A) 9,756,122 8,500,000 2.13 1M LIBOR+ GS Mortgage Securities Corp Trust 90bps 2017-500K, Floating Rate Note, 7/15/32 (144A) 8,505,216 3,500,000 2.33 1M LIBOR+ GS Mortgage Securities Corp Trust 110bps 2017-STAY, Floating Rate Note, 7/15/32 (144A) 3,471,953 8,350,000 4.96 GS Mortgage Securities RE-Remic Trust 2015-Frr1, Variable Rate Note, 6/27/41 8,325,903 1,514,020 5.13 1M LIBOR+ GS Mortgage Securities Trust 2014-GSFL, 390bps Floating Rate Note, 7/15/31 (144A) 1,517,636 67,169 2.01 1M LIBOR+ GSAA Home Equity Trust 2004-6, Floating 78bps Rate Note, 6/25/34 67,735 292,124 1.98 1M LIBOR+ GSAA Home Equity Trust 2004-8, Floating 74bps Rate Note, 9/25/34 292,150 The accompanying notes are an integral part of these financial statements. 46 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 203,132 2.36 1M LIBOR+ HarborView Mortgage Loan Trust 2004-4, 112.5bps Floating Rate Note, 6/19/34 $ 196,851 4,765,655 2.88 1M LIBOR+ Home Partners of America 2016-1 Trust, 165bps Floating Rate Note, 3/17/33 (144A) 4,816,316 1,799,000 4.54 1M LIBOR+ Home Partners of America 2016-1 Trust, 330bps Floating Rate Note, 3/18/33 (144A) 1,834,071 1,250,000 3.64 1M LIBOR+ Home Partners of America 2016-2 Trust, 240bps Floating Rate Note, 10/17/33 (144A) 1,264,224 9,932,698 2.05 1M LIBOR+ Home Partners of America 2017-1 Trust, 81.7bps Floating Rate Note, 7/17/34 (144A) 9,923,776 6,200,000 2.58 1M LIBOR+ Home Partners of America 2017-1 Trust, 135bps Floating Rate Note, 7/17/34 (144A) 6,227,994 1,596,967 1.97 1M LIBOR+ HomeBanc Mortgage Trust 2004-2, 74bps Floating Rate Note, 12/25/34 1,575,875 5,558,225 1.48 1M LIBOR+ HomeBanc Mortgage Trust 2005-3, 24bps Floating Rate Note, 7/25/35 5,526,058 1,063,227 2.34 1M LIBOR+ Homestar Mortgage Acceptance Corp. 110bps REMICS, Floating Rate Note, 9/25/34 1,058,539 3,892,772 1.88 1M LIBOR+ Homestar Mortgage Acceptance Corp., 64bps Floating Rate Note, 3/25/34 3,837,956 430,786 1.94 1M LIBOR+ Homestar Mortgage Acceptance Corp., 70bps Floating Rate Note, 6/25/34 433,045 642,976 2.40 1M LIBOR+ Homestar Mortgage Acceptance Corp., 58bps Floating Rate Note, 7/25/34 645,538 4,000,000 4.78 1M LIBOR+ Hospitality 2017-HIT Mortgage Trust, 355bps Floating Rate Note, 5/8/30 (144A) 4,002,408 3,500,000 2.81 1M LIBOR+ Hudsons Bay Simon JV Trust 2015-HBS, 158bps Floating Rate Note, 8/7/34 (144A) 3,519,428 8,000,000 2.23 Hunt CRE 2017-FL1, Ltd., Floating Rate Note, 8/15/34 (144A) 8,004,826 476,895 2.13 1M LIBOR+ Impac CMB Trust Series 2003-8, 90bps Floating Rate Note, 10/25/33 472,567 331,776 2.07 1M LIBOR+ Impac CMB Trust Series 2004-5, Floating 84bps Rate Note, 8/25/34 328,305 334,877 3.86 1M LIBOR+ Impac CMB Trust Series 2004-8, Floating 175bps Rate Note, 8/25/34 321,126 8,380,000 2.14 1M LIBOR+ Impac Secured Assets Corp Series 2004-3, 90bps Floating Rate Note, 11/25/34 8,252,968 386,819 2.10 1M LIBOR+ Impac Secured Assets Corp Series 2004-4, 86bps Floating Rate Note, 2/25/35 387,124 8,300,000 N/A 1M LIBOR+ IMT Trust 2017-APTS, Floating Rate Note, 95bps 6/15/34 (144A) 8,299,993 6,600,000 2.84 1M LIBOR+ Invitation Homes 2014-SFR2 Trust, 160bps Floating Rate Note, 9/19/31 (144A) 6,599,991 370,465 2.44 1M LIBOR+ Invitation Homes 2014-SFR3 Trust, 120bps Floating Rate Note, 12/17/31 (144A) 370,580 389,794 2.58 1M LIBOR+ Invitation Homes 2015-SFR2 Trust REMICS, 135bps Floating Rate Note, 6/17/32 (144A) 392,575 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 47 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 2,987,000 3.24 1M LIBOR+ Invitation Homes 2015-SFR2 Trust, Floating 200bps Rate Note, 6/17/32 (144A) $ 2,997,503 3,500,000 2.98 1M LIBOR+ Invitation Homes 2015-SFR3 Trust, Floating 175bps Rate Note, 8/17/32 (144A) 3,512,882 7,900,000 2.74 1M LIBOR+ J.P. Morgan Chase Commercial Mortgage 150bps Securities Trust 2016-ASH, Floating Rate Note, 10/15/34 (144A) 7,929,713 3,600,000 3.34 1M LIBOR+ J.P. Morgan Chase Commercial Mortgage 210bps Securities Trust 2016-WPT, Floating Rate Note, 10/15/33 (144A) 3,613,504 4,400,000 2.58 1M LIBOR+ J.P. Morgan Chase Commercial Mortgage 135bps Securities Trust 2016-WSP, Floating Rate Note, 8/15/33 (144A) 4,412,420 15,094 6.36 JP Morgan Chase Commercial Mortgage Securities Corp. Pass-Through Certificates Series 2002 CIBC4, Variable Rate Note, 5/12/34 15,191 215,151 4.84 JP Morgan Chase Commercial Mortgage Securities Trust 2004-LN2, Variable Rate Note, 7/15/41 (144A) 214,872 56,280 1.39 1M LIBOR+ JP Morgan Chase Commercial Mortgage 15.5bps Securities Trust 2006-LDP9, Floating Rate Note, 5/15/47 56,131 2,088,501 3.50 JP Morgan Chase Commercial Mortgage Securities Trust 2013-A5, Variable Rate Note, 7/25/20 2,112,323 4,280,000 2.63 1M LIBOR+ JP Morgan Chase Commercial Mortgage 140bps Securities Trust 2014-CBM, Floating Rate Note, 10/15/29 (144A) 4,280,003 3,470,000 3.18 1M LIBOR+ JP Morgan Chase Commercial Mortgage 195bps Securities Trust 2014-CBM, Floating Rate Note, 10/15/29 (144A) 3,470,001 1,250,000 3.43 1M LIBOR+ JP Morgan Chase Commercial Mortgage 220bps Securities Trust 2014-FL4 REMICS, Floating Rate Note, 12/16/30 (144A) 1,258,543 450,476 2.98 1M LIBOR+ JP Morgan Chase Commercial Mortgage 175bps Securities Trust 2014-FL4, Floating Rate Note, 12/16/30 (144A) 450,591 2,600,000 3.34 1M LIBOR+ JP Morgan Chase Commercial Mortgage 210bps Securities Trust 2014-FL5 REMICS, Floating Rate Note, 7/15/31 (144A) 2,575,066 1,000,000 2.58 1M LIBOR+ JP Morgan Chase Commercial Mortgage 135bps Securities Trust 2014-FL5, Floating Rate Note, 7/15/31 (144A) 1,005,846 2,932,484 2.63 1M LIBOR+ JP Morgan Chase Commercial Mortgage 140bps Securities Trust 2014-FL6, Floating Rate Note, 11/17/31 (144A) 2,941,052 3,770,000 3.08 1M LIBOR+ JP Morgan Chase Commercial Mortgage 185bps Securities Trust 2014-PHH, Floating Rate Note, 8/16/27 (144A) 3,770,004 The accompanying notes are an integral part of these financial statements. 48 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 537,996 2.48 1M LIBOR+ JP Morgan Chase Commercial Mortgage 125bps Securities Trust 2015-FL7 REMICS, Floating Rate Note, 5/15/28 (144A) $ 537,799 3,600,000 3.04 1M LIBOR+ JP Morgan Chase Commercial Mortgage 180bps Securities Trust 2015-FL7, Floating Rate Note, 5/15/28 (144A) 3,589,707 4,500,000 3.98 1M LIBOR+ JP Morgan Chase Commercial Mortgage 275bps Securities Trust 2015-SGP, Floating Rate Note, 7/15/36 (144A) 4,533,695 4,111,802 1.74 1M LIBOR JP Morgan Seasoned Mortgage Trust 2014-1, Floating Rate Note, 5/25/33 (144A) 4,077,829 7,727,146 2.00 JP Morgan Seasoned Mortgage Trust 2014-1, Variable Rate Note, 5/25/33 (144A) 7,662,091 103,903 1.46 1M LIBOR+ Lehman Brothers Small Balance 22bps Commercial Mortgage Trust 2006-1, Floating Rate Note, 4/25/31 (144A) 103,242 213,540 1.47 1M LIBOR+ Lehman Brothers Small Balance 23bps Commercial Mortgage Trust 2006-1, Floating Rate Note, 4/25/31 (144A) 212,510 940,605 1.93 1M LIBOR+ Lehman XS Trust Series 2005-2, Floating 70bps Rate Note, 8/25/35 921,391 10,000,000 2.99 1M LIBOR+ LMREC 2015-CRE1, Inc., Floating Rate 175bps Note, 2/24/32 (144A) 10,110,755 3,097,747 3.24 1M LIBOR+ LSTAR Securities Investment, Ltd. 2016-4, 200bps Floating Rate Note, 10/1/21 (144A) 3,092,792 3,673,473 3.24 1M LIBOR+ LSTAR Securities Investment, Ltd. 2016-5, 200bps Floating Rate Note, 11/1/21 (144A) 3,673,144 5,549,151 3.24 1M LIBOR+ LSTAR Securities Investment, Ltd. 2016-7, 200bps Floating Rate Note, 12/1/21 (144A) 5,549,151 3,666,012 3.24 1M LIBOR+ LSTAR Securities Investment, Ltd. 2017-2, 200bps Floating Rate Note, 2/1/22 (144A) 3,668,347 3,506,151 3.24 1M LIBOR+ LSTAR Securities Investment, Ltd. 2017-3, 200bps Floating Rate Note, 4/1/22 (144A) 3,518,725 8,000,000 0.00 1M LIBOR+ LSTAR Securities Investment, Ltd. 2017-6, 175bps Floating Rate Note, 9/1/22 (144A) 7,993,280 1,000,181 MarketPlace Loan Trust 2016-BS1, 4.5%, 1/15/21 (144A) 1,002,274 1,123,389 1.67 1M LIBOR+ Mellon Residential Funding Corp. Mortgage 44bps Pass-Through Trust Series 2000-TBC3, Floating Rate Note, 12/15/30 1,087,771 1,776,610 1.90 1M LIBOR+ Merrill Lynch Mortgage Investors Trust 66bps Series MLCC 2003-C REMICS, Floating Rate Note, 6/25/28 1,705,567 1,592,695 2.15 6M LIBOR+ Merrill Lynch Mortgage Investors Trust 70bps Series MLCC 2003-C, Floating Rate Note, 6/25/28 1,578,361 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 49 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 533,317 1.88 1M LIBOR+ Merrill Lynch Mortgage Investors Trust 64bps Series MLCC 2003-G, Floating Rate Note, 1/25/29 $ 514,180 143,504 2.79 Merrill Lynch Mortgage Investors Trust Series MLCC 2003-G, Variable Rate Note, 1/25/29 142,638 983,199 1.88 1M LIBOR+ Merrill Lynch Mortgage Investors Trust 64bps Series MLCC 2003-H, Floating Rate Note, 1/25/29 971,172 266,019 1.95 6M LIBOR+ Merrill Lynch Mortgage Investors Trust 54bps Series MLCC 2004-B, Floating Rate Note, 5/25/29 263,301 78,493 2.45 6M LIBOR+ Merrill Lynch Mortgage Investors Trust 100bps Series MLCC 2004-C, Floating Rate Note, 7/25/29 76,001 289,993 3.09 Merrill Lynch Mortgage Investors Trust Series MLCC 2004-D, Variable Rate Note, 9/25/29 288,802 330,187 2.05 6M LIBOR+ Merrill Lynch Mortgage Investors Trust 60bps Series MLCC 2004-G, Floating Rate Note, 1/25/30 322,960 1,421,806 1.70 1M LIBOR+ Merrill Lynch Mortgage Investors Trust 46bps Series MLCC 2005-A, Floating Rate Note, 3/25/30 1,375,218 2,888,861 Morgan Stanley Capital I Trust 2007-HQ13, 5.569%, 12/15/44 2,891,491 2,602,159 5.57 Morgan Stanley Capital I Trust 2007-TOP25, Variable Rate Note, 11/12/49 2,633,905 3,542,482 2.98 1M LIBOR+ Morgan Stanley Capital I Trust 2015-XLF1, 175bps Floating Rate Note, 8/14/31 (144A) 3,553,829 2,970,000 3.43 1M LIBOR+ Morgan Stanley Capital I Trust 2015-XLF1, 220bps Floating Rate Note, 8/14/31 (144A) 2,981,756 3,000,000 3.98 1M LIBOR+ Morgan Stanley Capital I Trust 2015-XLF1, 275bps Floating Rate Note, 8/17/26 (144A) 2,994,601 3,500,000 2.58 1M LIBOR+ Morgan Stanley Capital I Trust 2017-PRME, 135bps Floating Rate Note, 2/15/34 (144A) 3,514,066 879,736 1.78 Morgan Stanley Mortgage Loan Trust 2005-5AR, Floating Rate Note, 9/25/35 879,828 1,053,287 1.52 1M LIBOR+ Morgan Stanley Mortgage Loan Trust 28bps 2005-6AR, Floating Rate Note, 11/25/35 1,057,636 2,191,457 2.02 1M LIBOR+ MortgageIT Trust 2004-1, Floating Rate 77.99 Note, 11/25/34 2,144,389 9,300,000 2.64 1M LIBOR+ Motel 6 Trust 2017-MTL6, Floating Rate 140bps Note, 8/15/34 (144A) 9,302,935 1,500,000 2.32 3M LIBOR+ Nelder Grove CLO, Ltd., Floating Rate 100bps Note, 8/28/26 (144A) 1,499,988 1,259,689 3.21 3M LIBOR+ Newstar Trust, Floating Rate Note, 190bps 1/20/23 (144A) 1,259,785 The accompanying notes are an integral part of these financial statements. 50 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 4,315,478 2.83 1M LIBOR+ NorthStar 2016-1, Floating Rate Note, 160bps 9/25/31 (144A) $ 4,325,102 5,100,000 2.31 3M LIBOR+ Octagon Investment Partners XVII, Ltd., 100bps Floating Rate Note, 10/25/25 (144A) 5,104,621 2,733,756 1.63 1M LIBOR+ Opteum Mortgage Acceptance Corp 39bps Asset Backed Pass-Through Certificates 2005-4, Floating Rate Note, 11/25/35 2,684,306 2,018,927 2.28 3M LIBOR+ Palmer Square CLO 2013-1, Ltd., 97bps Floating Rate Note, 5/15/25 (144A) 2,021,361 3,500,000 1.89 1M LIBOR+ Pepper Residential Securities Trust NO 16, 65bps Floating Rate Note, 3/13/18 (144A) 3,496,700 2,086,031 2.86 1M LIBOR+ Pepper Residential Securities Trust No 17, 110bps Floating Rate Note, 3/10/58 (144A) 2,089,164 6,415,182 2.19 1M LIBOR+ Pepper Residential Securities Trust NO 18, 95bps Floating Rate Note, 3/12/47 (144A) 6,425,592 1,944,498 2.68 1M LIBOR+ PFP 2015-2, Ltd., Floating Rate Note, 145bps 7/14/34 (144A) 1,943,432 2,572,442 2.28 1M LIBOR+ PFP 2017-3, Ltd., Floating Rate Note, 105bps 1/14/35 (144A) 2,576,455 1,593,388 3.50 PMT Loan Trust 2013-J1, Variable Rate Note, 9/25/43 (144A) 1,597,239 3,750,867 Pretium Mortgage Credit Partners I 2016-NPL5 LLC, 9/27/31 (Step) (144A) 3,767,118 8,773,159 2.74 1M LIBOR+ Progress Residential 2016-SFR1 Trust, 150bps Floating Rate Note, 9/17/33 (144A) 8,906,474 1,944,000 3.74 1M LIBOR+ Progress Residential 2016-SFR1 Trust, 250bps Floating Rate Note, 9/17/33 (144A) 1,980,256 1,700,000 2.63 1M LIBOR+ Progress Residential 2016-SFR2 Trust, 140bps Floating Rate Note, 1/17/34 (144A) 1,724,398 2,400,000 2.98 1M LIBOR+ Progress Residential 2016-SFR2 Trust, 175bps Floating Rate Note, 1/17/34 (144A) 2,424,363 1,153,073 2.68 1M LIBOR+ RAIT 2016-FL6 Trust, Floating Rate Note, 145bps 11/13/31 (144A) 1,152,509 3,673 1.78 1M LIBOR+ RALI Series 2002-QS16 Trust, Floating 55bps Rate Note, 10/25/17 3,670 79,985 1.69 1M LIBOR+ RALI Series 2003-QS5 Trust, Floating 45bps Rate Note, 3/25/18 79,611 2,491,147 2.22 1M LIBOR+ ReadyCap Commercial Mortgage Trust 85bps 2017-1, Floating Rate Note, 5/25/34 (144A) 2,491,147 2,141,394 ReadyCap Mortgage Trust 2016-3, 2.93997%, 11/20/38 (144A) 2,152,051 3,313,199 2.68 1M LIBOR+ RESI Finance LP 2003-CB1, Floating 145bps Rate Note, 7/9/35 2,982,558 1,217,778 2.01 RESI MAC, 2014-1A, Floating Rate Note, 6/12/19 1,218,437 2,640,409 2.62 1M LIBOR+ Resimac Premier Series 2016-1, Floating 139bps Rate Note, 10/10/47 (144A) 2,657,437 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 51 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 6,979,120 2.18 1M LIBOR+ RESIMAC Premier Series 2017-1, Floating 95bps Rate Note, 9/11/48 (144A) $ 6,979,643 523,270 2.63 1M LIBOR+ Resource Capital Corp 2015-CRE4, Ltd., 140bps Floating Rate Note, 8/15/32 (144A) (e) 522,395 5,700,000 2.03 1M LIBOR+ Resource Capital Corp 2017-CRE5, Ltd., 80bps Floating Rate Note, 7/15/34 (144A) 5,712,449 179,870 2.76 Sequoia Mortgage Trust 2004-7, Variable Rate Note, 8/20/34 180,643 750,000 2.16 3M LIBOR+ Silver Creek CLO, Ltd., Floating Rate Note, 85bps 7/20/30 (144A) 750,050 272,389 1.78 Springleaf Mortgage Loan Trust 2013-2, Variable Rate Note, 12/28/65 (144A) 272,000 7,500,000 N/A 1M LIBOR+ Starwood Waypoint Homes 2017-1 Trust, 117bps Floating Rate Note, 1/17/35 (144A) 7,422,350 8,300,000 2.42 1M LIBOR+ Stonemont Portfolio Trust 2017-STONE, 110bps Floating Rate Note, 8/20/30 (144A) 8,312,765 163,606 2.18 1M LIBOR+ Structured Asset Securities Corp. Mortgage 94bps Pass-Through Certificates Series 1998-8, Floating Rate Note, 8/25/28 164,926 36,264 1.74 1M LIBOR+ Structured Asset Securities Corp. Mortgage 50bps Pass-Through Certificates Series 2003-35, Floating Rate Note, 12/25/33 36,232 222,534 1.53 1M LIBOR+ Structured Asset Securities Corp. Trust 30bps 2005-14, Floating Rate Note, 7/25/35 184,151 8,203,929 3.19 Sutherland Commercial Mortgage Loans 2017-SBC6, Floating Rate Note, 5/25/37 (144A) 8,205,094 6,420,000 2.97 Symphony CLO VIII LP, Floating Rate Note, 1/9/23 (144A) 6,438,515 2,450,000 N/A 3M LIBOR+ TCI-Symphony CLO 2017-1, Ltd., Floating 80bps Rate Note, 7/15/30 (144A) 2,449,951 389,301 2.64 Thornburg Mortgage Securities Trust 2004-4, Variable Rate Note, 12/25/44 391,013 1,053,446 3.06 Thornburg Mortgage Securities Trust 2005-1, Variable Rate Note, 4/25/45 1,055,816 4,612,321 3.50 Towd Point Mortgage Trust 2015-4 REMICS, Variable Rate Note, 4/25/55 (144A) 4,702,116 4,150,000 2.88 1M LIBOR+ Tricon American Homes 2015-SFR1 Trust 165bps REMICS, Floating Rate Note, 5/19/32 (144A) 4,164,376 391,900 3.23 1M LIBOR+ Velocity Commercial Capital Loan Trust 200bps 2014-1, Floating Rate Note, 9/25/44 (144A) 392,094 909,077 5.82 Wachovia Bank Commercial Mortgage Trust Series 2007-C34 REMICS, Variable Rate Note, 5/15/46 908,826 4,477,000 2.19 WaMu Commercial Mortgage Securities Trust 2006-SL1, Variable Rate Note, 11/23/43 (144A) 4,483,654 The accompanying notes are an integral part of these financial statements. 52 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 5,677,000 2.32 WaMu Commercial Mortgage Securities Trust 2006-SL1, Variable Rate Note, 11/23/43 (144A) $ 5,464,637 2,500,000 3.08 1M LIBOR+ Wells Fargo Commercial Mortgage Trust 185bps 2014-TISH REMICS, Floating Rate Note, 2/15/27 (144A) 2,507,641 1,500,000 4.73 1M LIBOR+ Wells Fargo Commercial Mortgage Trust 350bps 2014-TISH, Floating Rate Note, 1/15/27 (144A) 1,499,009 642,201 3.99 1M LIBOR+ Wells Fargo Credit Risk Transfer Securities 275bps Trust 2015, Floating Rate Note, 11/25/25 (144A) 645,161 903,811 4.09 1M LIBOR+ Wells Fargo Credit Risk Transfer Securities 285bps Trust 2015, Floating Rate Note, 11/25/25 (144A) 913,229 4,758,143 3.00 WinWater Mortgage Loan Trust 2015-2, Variable Rate Note, 2/20/45 (144A) 4,788,627 -------------- $ 748,732,145 -------------- Total Banks $ 750,481,312 -------------------------------------------------------------------------------------------------------------- DIVERSIFIED FINANCIALS -- 0.4% Other Diversified Financial Services -- 0.3% 2,161,673 5.88 Banc of America Commercial Mortgage Trust 2007-3, Variable Rate Note, 6/10/49 $ 2,178,447 2,000,000 3.38 1M LIBOR+ Colony American Homes 2014-1 REMICS, 215bps Floating Rate Note, 5/17/31 (144A) 2,007,618 1,711,582 3.14 1M LIBOR+ Colony American Homes 2014-2, Floating 190bps Rate Note, 7/17/31 (144A) 1,720,822 4,333,841 6.50 Morgan Stanley Capital I Trust 2008-TOP29 REMICS, Variable Rate Note, 1/11/43 4,360,388 -------------- $ 10,267,275 -------------------------------------------------------------------------------------------------------------- Specialized Finance -- 0.1% 4,770,000 3.23 1M LIBOR+ BAMLL Commercial Mortgage Securities 200bps Trust 2015-ASHF REMICS, Floating Rate Note, 1/15/28 (144A) $ 4,781,334 -------------- Total Diversified Financials $ 15,048,609 -------------------------------------------------------------------------------------------------------------- Government -- 4.0% 783,552 3.23 1M LIBOR+ Fannie Mae Connecticut Avenue 200bps Securities, Floating Rate Note, 10/25/23 $ 790,112 25,357 2.84 1M LIBOR+ Fannie Mae Connecticut Avenue 160bps Securities, Floating Rate Note, 4/25/28 25,364 966,809 2.18 1M LIBOR+ Fannie Mae Connecticut Avenue 95bps Securities, Floating Rate Note, 5/25/24 970,510 1,589,042 2.43 1M LIBOR+ Fannie Mae Connecticut Avenue 120bps Securities, Floating Rate Note, 7/25/24 1,590,851 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 53 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Government -- (continued) 1,333,097 3.19 1M LIBOR+ Fannie Mae Connecticut Avenue 195bps Securities, Floating Rate Note, 8/25/28 $ 1,344,924 1,335,730 3.39 1M LIBOR+ Fannie Mae Connecticut Avenue 215bps Securities, Floating Rate Note, 9/25/28 1,350,362 2,436,842 1.58 Fannie Mae Trust 2003-W6, Variable Rate Note, 9/25/42 2,423,035 147,989 2.90 Fannie Mae Trust 2005-W4, Variable Rate Note, 6/26/45 157,529 1,153,384 1.49 1M LIBOR+ Fannie Mae Whole Loan, Floating Rate 26bps Note, 11/25/46 1,155,499 713,998 Fannie Mae, 2.5%, 6/25/24 716,451 542,968 Fannie Mae, 3.0%, 1/25/29 544,669 491,409 Fannie Mae, 3.0%, 11/25/18 492,908 100,755 Fannie Mae, 3.0%, 8/25/25 101,030 343,760 Fannie Mae, 3.5%, 6/25/21 347,585 645,099 Fannie Mae, 4.5%, 9/25/18 650,324 42,484 Fannie Mae, 4.5%, 9/25/35 42,437 3,598,591 1.53 1M LIBOR+ Fannie Mae, Floating Rate Note, 12/25/33 30bps 3,587,501 1,566,579 1.68 1M LIBOR+ Fannie Mae, Floating Rate Note, 9/25/39 45bps 1,570,277 644,124 1.63 1M LIBOR+ Federal Home Loan Mortgage Corp. 40bps REMICS, Floating Rate Note, 1/15/33 644,529 155,136 1.53 1M LIBOR+ Federal Home Loan Mortgage Corp. 30bps REMICS, Floating Rate Note, 1/15/36 155,048 1,445,968 1.53 1M LIBOR+ Federal Home Loan Mortgage Corp. 30bps REMICS, Floating Rate Note, 1/15/37 1,438,917 15,401 1.38 1M LIBOR+ Federal Home Loan Mortgage Corp. 15bps REMICS, Floating Rate Note, 10/15/20 15,394 46,350 2.18 1M LIBOR+ Federal Home Loan Mortgage Corp. 58bps REMICS, Floating Rate Note, 10/15/31 47,049 655,606 1.81 1M LIBOR+ Federal Home Loan Mortgage Corp. 62bps REMICS, Floating Rate Note, 10/15/37 660,254 195,252 1.85 1M LIBOR+ Federal Home Loan Mortgage Corp. 60bps REMICS, Floating Rate Note, 10/15/37 197,944 64,962 1.83 1M LIBOR+ Federal Home Loan Mortgage Corp. 100bps REMICS, Floating Rate Note, 11/15/31 65,934 152,090 2.23 1M LIBOR+ Federal Home Loan Mortgage Corp. 35bps REMICS, Floating Rate Note, 11/15/33 155,832 103,461 1.58 1M LIBOR+ Federal Home Loan Mortgage Corp. 35bps REMICS, Floating Rate Note, 11/15/35 103,325 475,871 1.58 1M LIBOR+ Federal Home Loan Mortgage Corp. 35bps REMICS, Floating Rate Note, 11/15/36 475,665 247,199 1.58 1M LIBOR+ Federal Home Loan Mortgage Corp. 35bps REMICS, Floating Rate Note, 11/15/36 247,094 131,204 1.63 1M LIBOR+ Federal Home Loan Mortgage Corp. 40bps REMICS, Floating Rate Note, 11/15/40 131,358 The accompanying notes are an integral part of these financial statements. 54 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Government -- (continued) 53,346 1.63 1M LIBOR+ Federal Home Loan Mortgage Corp. 40bps REMICS, Floating Rate Note, 12/15/20 $ 53,559 277,044 1.68 1M LIBOR+ Federal Home Loan Mortgage Corp. 45bps REMICS, Floating Rate Note, 12/15/28 277,717 94,486 1.58 1M LIBOR+ Federal Home Loan Mortgage Corp. 35bps REMICS, Floating Rate Note, 12/15/32 94,413 15,559 1.73 1M LIBOR+ Federal Home Loan Mortgage Corp. 50bps REMICS, Floating Rate Note, 12/15/32 15,623 143,556 1.63 1M LIBOR+ Federal Home Loan Mortgage Corp. 40bps REMICS, Floating Rate Note, 12/15/32 143,902 107,636 1.63 1M LIBOR+ Federal Home Loan Mortgage Corp. 40bps REMICS, Floating Rate Note, 12/15/32 107,843 527,041 1.93 1M LIBOR+ Federal Home Loan Mortgage Corp. 70bps REMICS, Floating Rate Note, 12/15/39 534,490 323,175 1.58 1M LIBOR+ Federal Home Loan Mortgage Corp. 35bps REMICS, Floating Rate Note, 12/15/41 321,899 12,239 1.46 1M LIBOR+ Federal Home Loan Mortgage Corp. 23bps REMICS, Floating Rate Note, 2/15/19 12,238 43,984 1.53 1M LIBOR+ Federal Home Loan Mortgage Corp. 30bps REMICS, Floating Rate Note, 2/15/25 44,005 154,899 1.58 1M LIBOR+ Federal Home Loan Mortgage Corp. 35bps REMICS, Floating Rate Note, 2/15/29 154,741 359,572 1.53 1M LIBOR+ Federal Home Loan Mortgage Corp. 30bps REMICS, Floating Rate Note, 2/15/30 359,968 347,869 1.63 1M LIBOR+ Federal Home Loan Mortgage Corp. 40bps REMICS, Floating Rate Note, 2/15/33 348,174 197,698 1.78 1M LIBOR+ Federal Home Loan Mortgage Corp. 55bps REMICS, Floating Rate Note, 2/15/33 199,958 500,930 1.53 1M LIBOR+ Federal Home Loan Mortgage Corp. 30bps REMICS, Floating Rate Note, 2/15/36 501,810 169,689 1.58 1M LIBOR+ Federal Home Loan Mortgage Corp. 35bps REMICS, Floating Rate Note, 2/15/36 169,902 265,502 1.53 1M LIBOR+ Federal Home Loan Mortgage Corp. 30bps REMICS, Floating Rate Note, 2/15/39 266,357 747,498 2.28 1M LIBOR+ Federal Home Loan Mortgage Corp. 105bps REMICS, Floating Rate Note, 3/15/24 763,599 369,212 2.23 1M LIBOR+ Federal Home Loan Mortgage Corp. 100bps REMICS, Floating Rate Note, 3/15/32 378,031 117,413 1.93 1M LIBOR+ Federal Home Loan Mortgage Corp. 70bps REMICS, Floating Rate Note, 3/15/32 118,895 548,448 2.23 1M LIBOR+ Federal Home Loan Mortgage Corp. 100bps REMICS, Floating Rate Note, 3/15/32 564,523 494,816 1.53 1M LIBOR+ Federal Home Loan Mortgage Corp. 30bps REMICS, Floating Rate Note, 3/15/36 494,545 38,172 1.68 1M LIBOR+ Federal Home Loan Mortgage Corp. 45bps REMICS, Floating Rate Note, 3/15/39 38,256 1,126,090 1.63 1M LIBOR+ Federal Home Loan Mortgage Corp. 40bps REMICS, Floating Rate Note, 3/15/41 1,128,773 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 55 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Government -- (continued) 300,748 1.53 1M LIBOR+ Federal Home Loan Mortgage Corp. 30bps REMICS, Floating Rate Note, 4/15/36 $ 300,463 65,099 1.58 1M LIBOR+ Federal Home Loan Mortgage Corp. 35bps REMICS, Floating Rate Note, 5/15/29 65,497 222,827 2.74 1M LIBOR+ Federal Home Loan Mortgage Corp. 150bps REMICS, Floating Rate Note, 5/15/33 227,987 523,522 1.57 1M LIBOR+ Federal Home Loan Mortgage Corp. 34bps REMICS, Floating Rate Note, 5/15/35 523,713 104,813 1.53 1M LIBOR+ Federal Home Loan Mortgage Corp. 30bps REMICS, Floating Rate Note, 5/15/35 104,955 251,979 1.63 1M LIBOR+ Federal Home Loan Mortgage Corp. 40bps REMICS, Floating Rate Note, 5/15/36 252,481 89,724 1.57 1M LIBOR+ Federal Home Loan Mortgage Corp. 34bps REMICS, Floating Rate Note, 5/15/37 89,339 42,843 2.48 1M LIBOR+ Federal Home Loan Mortgage Corp. 125bps REMICS, Floating Rate Note, 5/15/37 44,269 52,698 1.58 1M LIBOR+ Federal Home Loan Mortgage Corp. 35bps REMICS, Floating Rate Note, 5/15/41 52,699 9,488 1.68 1M LIBOR+ Federal Home Loan Mortgage Corp. 45bps REMICS, Floating Rate Note, 6/15/23 9,497 293,068 1.63 1M LIBOR+ Federal Home Loan Mortgage Corp. 40bps REMICS, Floating Rate Note, 6/15/33 293,428 319,104 1.65 1M LIBOR+ Federal Home Loan Mortgage Corp. 42bps REMICS, Floating Rate Note, 6/15/36 319,811 1,083,068 1.54 1M LIBOR+ Federal Home Loan Mortgage Corp. 31bps REMICS, Floating Rate Note, 6/15/36 1,079,463 12,293 1.48 1M LIBOR+ Federal Home Loan Mortgage Corp. 25bps REMICS, Floating Rate Note, 7/15/21 12,315 267,341 1.63 1M LIBOR+ Federal Home Loan Mortgage Corp. 40bps REMICS, Floating Rate Note, 7/15/23 268,547 320,539 1.47 1M LIBOR+ Federal Home Loan Mortgage Corp. 24bps REMICS, Floating Rate Note, 7/15/34 317,837 593,965 1.73 1M LIBOR+ Federal Home Loan Mortgage Corp. 50bps REMICS, Floating Rate Note, 7/15/36 597,090 27,245 1.63 1M LIBOR+ Federal Home Loan Mortgage Corp. 40bps REMICS, Floating Rate Note, 7/15/36 27,238 191,466 1.43 1M LIBOR+ Federal Home Loan Mortgage Corp. 20bps REMICS, Floating Rate Note, 7/15/36 191,582 260,909 1.58 1M LIBOR+ Federal Home Loan Mortgage Corp. 35bps REMICS, Floating Rate Note, 7/15/40 260,907 217,807 1.43 1M LIBOR+ Federal Home Loan Mortgage Corp. 20bps REMICS, Floating Rate Note, 8/15/26 217,942 400,550 1.48 1M LIBOR+ Federal Home Loan Mortgage Corp. 25bps REMICS, Floating Rate Note, 8/15/35 400,634 228,758 1.48 1M LIBOR+ Federal Home Loan Mortgage Corp. 25bps REMICS, Floating Rate Note, 8/15/35 228,426 383,394 1.48 1M LIBOR+ Federal Home Loan Mortgage Corp. 25bps REMICS, Floating Rate Note, 8/15/36 382,233 The accompanying notes are an integral part of these financial statements. 56 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Government -- (continued) 436,351 1.53 1M LIBOR+ Federal Home Loan Mortgage Corp. 30bps REMICS, Floating Rate Note, 9/15/26 $ 437,498 86,490 1.83 1M LIBOR+ Federal Home Loan Mortgage Corp. 60bps REMICS, Floating Rate Note, 9/15/32 87,658 219,839 1.65 1M LIBOR+ Federal Home Loan Mortgage Corp. 42bps REMICS, Floating Rate Note, 9/15/36 220,630 140,196 1.63 1M LIBOR+ Federal Home Loan Mortgage Corp. 40bps REMICS, Floating Rate Note, 9/15/36 140,130 625,726 Federal Home Loan Mortgage Corp., 3.0%, 12/15/24 627,056 365,310 Federal Home Loan Mortgage Corp., 3.5%, 10/15/24 369,893 391,218 1.48 1M LIBOR+ Federal Home Loan Mortgage Corp., 25bps Floating Rate Note, 1/15/35 391,909 33,344 1.58 1M LIBOR+ Federal Home Loan Mortgage Corp., 35bps Floating Rate Note, 2/15/18 33,349 311,942 2.23 1M LIBOR+ Federal Home Loan Mortgage Corp., 100bps Floating Rate Note, 3/15/32 319,393 317,702 1.83 1M LIBOR+ Federal Home Loan Mortgage Corp., 60bps Floating Rate Note, 4/15/28 322,757 188,067 1.83 1M LIBOR+ Federal Home Loan Mortgage Corp., 60bps Floating Rate Note, 6/15/31 190,878 2,286,805 1.93 1M LIBOR+ Federal Home Loan Mortgage Corp., 70bps Floating Rate Note, 8/15/35 2,307,488 131,031 1.88 1M LIBOR+ Federal National Mortgage Association 65bps REMICS, Floating Rate Note, 1/18/32 133,082 207,302 1.93 1M LIBOR+ Federal National Mortgage Association 70bps REMICS, Floating Rate Note, 1/25/32 211,031 89,210 1.88 1M LIBOR+ Federal National Mortgage Association 65bps REMICS, Floating Rate Note, 1/25/33 90,799 228,664 1.73 1M LIBOR+ Federal National Mortgage Association 50bps REMICS, Floating Rate Note, 1/25/33 229,130 153,313 1.78 1M LIBOR+ Federal National Mortgage Association 55bps REMICS, Floating Rate Note, 1/25/40 154,070 342,289 1.53 1M LIBOR+ Federal National Mortgage Association 30bps REMICS, Floating Rate Note, 10/25/35 342,139 1,200,042 1.63 1M LIBOR+ Federal National Mortgage Association 40bps REMICS, Floating Rate Note, 10/25/36 1,198,106 67,634 1.78 1M LIBOR+ Federal National Mortgage Association 55bps REMICS, Floating Rate Note, 10/25/37 68,088 432,234 1.83 1M LIBOR+ Federal National Mortgage Association 60bps REMICS, Floating Rate Note, 10/25/37 436,733 324,074 2.45 1M LIBOR+ Federal National Mortgage Association 122bps REMICS, Floating Rate Note, 10/25/38 331,609 1,074,526 2.23 1M LIBOR+ Federal National Mortgage Association 100bps REMICS, Floating Rate Note, 11/18/32 1,099,308 258,543 1.83 1M LIBOR+ Federal National Mortgage Association 60bps REMICS, Floating Rate Note, 11/25/31 262,521 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 57 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Government -- (continued) 227,517 1.83 1M LIBOR+ Federal National Mortgage Association 60bps REMICS, Floating Rate Note, 11/25/31 $ 231,018 389,747 1.73 1M LIBOR+ Federal National Mortgage Association 50bps REMICS, Floating Rate Note, 11/25/33 392,850 250,460 1.53 1M LIBOR+ Federal National Mortgage Association 30bps REMICS, Floating Rate Note, 11/25/34 251,638 196,882 1.55 1M LIBOR+ Federal National Mortgage Association 32bps REMICS, Floating Rate Note, 11/25/36 196,347 57,378 1.83 1M LIBOR+ Federal National Mortgage Association 60bps REMICS, Floating Rate Note, 12/25/23 57,525 171,124 2.23 1M LIBOR+ Federal National Mortgage Association 100bps REMICS, Floating Rate Note, 12/25/23 172,946 57,137 1.78 1M LIBOR+ Federal National Mortgage Association 55bps REMICS, Floating Rate Note, 12/25/30 58,054 424,680 2.13 1M LIBOR+ Federal National Mortgage Association 90bps REMICS, Floating Rate Note, 12/25/31 430,353 215,609 1.83 1M LIBOR+ Federal National Mortgage Association 60bps REMICS, Floating Rate Note, 12/25/32 217,243 107,164 1.47 1M LIBOR+ Federal National Mortgage Association 24bps REMICS, Floating Rate Note, 12/25/36 106,562 239,027 1.85 1M LIBOR+ Federal National Mortgage Association 62bps REMICS, Floating Rate Note, 12/25/37 239,756 70,252 1.63 1M LIBOR+ Federal National Mortgage Association 40bps REMICS, Floating Rate Note, 12/25/38 70,404 186,653 1.98 1M LIBOR+ Federal National Mortgage Association 75bps REMICS, Floating Rate Note, 2/25/33 190,272 459,157 1.58 1M LIBOR+ Federal National Mortgage Association 35bps REMICS, Floating Rate Note, 2/25/33 462,597 505,880 1.54 1M LIBOR+ Federal National Mortgage Association 31bps REMICS, Floating Rate Note, 2/25/35 504,208 272,662 1.48 1M LIBOR+ Federal National Mortgage Association 25bps REMICS, Floating Rate Note, 2/25/37 270,652 256,027 1.43 1M LIBOR+ Federal National Mortgage Association 20bps REMICS, Floating Rate Note, 2/25/37 254,347 125,255 1.93 1M LIBOR+ Federal National Mortgage Association 70bps REMICS, Floating Rate Note, 2/25/38 126,771 34,658 1.73 1M LIBOR+ Federal National Mortgage Association 50bps REMICS, Floating Rate Note, 3/25/23 34,673 300,028 1.73 1M LIBOR+ Federal National Mortgage Association 50bps REMICS, Floating Rate Note, 3/25/24 303,230 150,510 1.57 T1Y+35bps Federal National Mortgage Association REMICS, Floating Rate Note, 3/25/28 151,168 891,105 1.63 1M LIBOR+ Federal National Mortgage Association 40bps REMICS, Floating Rate Note, 3/25/34 891,360 73,356 1.53 1M LIBOR+ Federal National Mortgage Association 30bps REMICS, Floating Rate Note, 3/25/36 72,464 90,443 2.23 1M LIBOR+ Federal National Mortgage Association 100bps REMICS, Floating Rate Note, 3/25/37 92,928 The accompanying notes are an integral part of these financial statements. 58 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Government -- (continued) 299,151 1.48 1M LIBOR+ Federal National Mortgage Association 25bps REMICS, Floating Rate Note, 3/25/37 $ 296,940 236,868 1.48 1M LIBOR+ Federal National Mortgage Association 25bps REMICS, Floating Rate Note, 3/25/37 236,142 1,068,498 1.45 1M LIBOR+ Federal National Mortgage Association 22bps REMICS, Floating Rate Note, 3/25/45 1,042,881 73,239 1.53 1M LIBOR+ Federal National Mortgage Association 30bps REMICS, Floating Rate Note, 4/25/25 73,239 1,160,740 2.13 1M LIBOR+ Federal National Mortgage Association 90bps REMICS, Floating Rate Note, 4/25/32 1,177,291 578,814 1.73 1M LIBOR+ Federal National Mortgage Association 50bps REMICS, Floating Rate Note, 4/25/33 581,592 3,243,101 1.63 1M LIBOR+ Federal National Mortgage Association 40bps REMICS, Floating Rate Note, 4/25/34 3,263,044 286,379 1.73 1M LIBOR+ Federal National Mortgage Association 50bps REMICS, Floating Rate Note, 4/25/42 287,249 225,197 1.73 1M LIBOR+ Federal National Mortgage Association 50bps REMICS, Floating Rate Note, 5/25/33 225,599 211,052 1.58 1M LIBOR+ Federal National Mortgage Association 35bps REMICS, Floating Rate Note, 5/25/36 210,324 639,968 1.54 1M LIBOR+ Federal National Mortgage Association 31bps REMICS, Floating Rate Note, 5/25/36 639,145 375,237 1.63 1M LIBOR+ Federal National Mortgage Association 40bps REMICS, Floating Rate Note, 5/25/37 376,173 129,505 1.83 1M LIBOR+ Federal National Mortgage Association 60bps REMICS, Floating Rate Note, 5/25/40 130,795 262,515 1.73 1M LIBOR+ Federal National Mortgage Association 50bps REMICS, Floating Rate Note, 5/25/40 263,533 450,365 1.78 1M LIBOR+ Federal National Mortgage Association 55bps REMICS, Floating Rate Note, 5/25/40 453,641 258,700 1.63 1M LIBOR+ Federal National Mortgage Association 40bps REMICS, Floating Rate Note, 6/25/23 259,711 413,435 1.68 1M LIBOR+ Federal National Mortgage Association 45bps REMICS, Floating Rate Note, 6/25/36 415,619 478,091 1.47 1M LIBOR+ Federal National Mortgage Association 45bps REMICS, Floating Rate Note, 6/25/37 476,108 44,085 1.46 1M LIBOR+ Federal National Mortgage Association 23bps REMICS, Floating Rate Note, 6/25/37 43,896 153,300 1.48 1M LIBOR+ Federal National Mortgage Association 45bps REMICS, Floating Rate Note, 6/25/37 152,188 47,053 1.68 1M LIBOR+ Federal National Mortgage Association 45bps REMICS, Floating Rate Note, 6/25/37 47,275 34,971 1.73 1M LIBOR+ Federal National Mortgage Association 50bps REMICS, Floating Rate Note, 7/18/27 35,385 250,221 1.83 1M LIBOR+ Federal National Mortgage Association 60bps REMICS, Floating Rate Note, 7/25/31 254,072 166,114 1.83 1M LIBOR+ Federal National Mortgage Association 60bps REMICS, Floating Rate Note, 7/25/31 168,925 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 59 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Government -- (continued) 108,050 2.23 1M LIBOR+ Federal National Mortgage Association 100bps REMICS, Floating Rate Note, 7/25/32 $ 110,009 294,350 1.63 1M LIBOR+ Federal National Mortgage Association 40bps REMICS, Floating Rate Note, 7/25/34 294,498 91,476 1.68 1M LIBOR+ Federal National Mortgage Association 45bps REMICS, Floating Rate Note, 7/25/34 91,522 1,213,045 1.53 1M LIBOR+ Federal National Mortgage Association 30bps REMICS, Floating Rate Note, 7/25/35 1,211,370 1,099,766 1.48 1M LIBOR+ Federal National Mortgage Association 25bps REMICS, Floating Rate Note, 7/25/35 1,098,226 158,395 1.52 1M LIBOR+ Federal National Mortgage Association 29bps REMICS, Floating Rate Note, 7/25/36 158,129 153,454 1.63 1M LIBOR+ Federal National Mortgage Association 40bps REMICS, Floating Rate Note, 7/25/37 153,862 104,464 1.73 1M LIBOR+ Federal National Mortgage Association 50bps REMICS, Floating Rate Note, 8/25/31 104,918 46,911 1.83 1M LIBOR+ Federal National Mortgage Association 60bps REMICS, Floating Rate Note, 8/25/32 47,594 159,324 1.73 1M LIBOR+ Federal National Mortgage Association 50bps REMICS, Floating Rate Note, 8/25/32 160,061 2,374 1.63 1M LIBOR+ Federal National Mortgage Association 40bps REMICS, Floating Rate Note, 8/25/33 2,378 103,659 1.78 1M LIBOR+ Federal National Mortgage Association 55bps REMICS, Floating Rate Note, 8/25/36 103,597 43 2.03 1M LIBOR+ Federal National Mortgage Association 80bps REMICS, Floating Rate Note, 9/25/20 44 39,109 2.13 1M LIBOR+ Federal National Mortgage Association 90bps REMICS, Floating Rate Note, 9/25/21 39,650 207,709 1.73 1M LIBOR+ Federal National Mortgage Association 50bps REMICS, Floating Rate Note, 9/25/32 208,483 1,069,728 1.73 1M LIBOR+ Federal National Mortgage Association 50bps REMICS, Floating Rate Note, 9/25/33 1,072,057 194,717 1.80 1M LIBOR+ Federal National Mortgage Association 57bps REMICS, Floating Rate Note, 9/25/36 196,273 436,140 1.73 1M LIBOR+ Federal National Mortgage Association 50bps REMICS, Floating Rate Note, 9/25/37 438,760 201,837 1.80 1M LIBOR+ Federal National Mortgage Association 57bps REMICS, Floating Rate Note, 9/25/37 204,360 111,272 1.78 1M LIBOR+ Federal National Mortgage Association 55bps REMICS, Floating Rate Note, 9/25/37 112,103 658,681 Federal National Mortgage Association, 2.5%, 4/25/36 659,272 171,124 2.11 D11COF+ Federal National Mortgage Association, 140bps Floating Rate Note, 12/25/23 170,781 4,126,561 1.53 1M LIBOR+ Federal National Mortgage Association, 30bps Floating Rate Note, 12/25/33 4,111,785 9,162,468 1.68 1M LIBOR+ Federal National Mortgage Association, 45bps Floating Rate Note, 2/25/38 9,182,283 The accompanying notes are an integral part of these financial statements. 60 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Government -- (continued) 103,999 1.53 1M LIBOR+ Federal National Mortgage Association, 30bps Floating Rate Note, 3/25/18 $ 103,996 85,735 3.21 Federal National Mortgage Association, Variable Rate Note, 4/25/35 87,915 282,671 1.58 1M LIBOR+ Freddie Mac Strips, Floating Rate Note, 35bps 12/15/36 282,871 212,056 1.48 1M LIBOR+ Freddie Mac Strips, Floating Rate Note, 25bps 8/15/36 211,460 916,727 1.53 1M LIBOR+ Freddie Mac Strips, Floating Rate Note, 30bps 8/15/36 915,770 2,675,000 3.44 1M LIBOR+ Freddie Mac Structured Agency Credit Risk 220bps Debt Notes, Floating Rate Note, 10/25/28 2,718,589 204,037 2.68 1M LIBOR+ Freddie Mac Structured Agency Credit Risk 145bps Debt Notes, Floating Rate Note, 11/25/23 204,499 459,002 2.43 1M LIBOR+ Freddie Mac Structured Agency Credit Risk 120bps Debt Notes, Floating Rate Note, 11/25/28 459,521 750,000 2.53 1M LIBOR+ Freddie Mac Structured Agency Credit Risk 130bps Debt Notes, Floating Rate Note, 3/25/29 759,375 699,984 2.68 1M LIBOR+ Freddie Mac Structured Agency Credit Risk 145bps Debt Notes, Floating Rate Note, 7/25/28 702,000 300,000 4.13 1M LIBOR+ Freddie Mac Structured Agency Credit Risk 290bps Debt Notes, Floating Rate Note, 7/25/28 310,002 707,115 2.98 1M LIBOR+ Freddie Mac Structured Agency Credit Risk 175bps Debt Notes, Floating Rate Note, 9/25/28 709,468 454,492 Freddie Mac, 2.0%, 11/15/20 455,934 530,101 Freddie Mac, 2.0%, 8/15/20 530,850 1,456,978 Freddie Mac, 3.0%, 10/15/25 1,469,169 1,093,085 Freddie Mac, 3.0%, 5/15/29 1,103,928 1,698,180 Freddie Mac, 3.1%, 2/15/25 1,705,286 543,297 Freddie Mac, 3.5%, 1/15/24 545,867 1,146,300 Freddie Mac, 4.5%, 4/15/19 1,163,213 791,643 Freddie Mac, 4.5%, 6/15/23 810,971 9,292,000 4.93 FREMF Mortgage Trust 2011-K702, Variable Rate Note, 4/25/44 (144A) 9,382,550 10,661,000 5.05 FREMF Mortgage Trust 2011-K703, Variable Rate Note, 7/25/44 (144A) 10,819,483 963,380 4.48 1M LIBOR+ FREMF Mortgage Trust 2014-KF04 REMICS, 325bps Floating Rate Note, 6/25/21 (144A) 973,406 2,715,816 5.23 1M LIBOR+ FREMF Mortgage Trust 2014-KF05 REMICS, 400bps Floating Rate Note, 9/25/21 (144A) 2,797,745 3,939,752 6.23 1M LIBOR+ FREMF Mortgage Trust 2014-KS02 REMICS, 500bps Floating Rate Note, 8/25/23 (144A) 3,923,166 9,161,779 5.63 1M LIBOR+ FREMF Mortgage Trust 2015-KLSF REMICS, 440bps Floating Rate Note, 11/25/22 (144A) 9,257,802 11,684,936 1.59 1M LIBOR+ Government National Mortgage Association 35bps REMICS, Floating Rate Note, 1/20/47 11,720,437 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 61 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Government -- (continued) 341,115 Government National Mortgage Association, 3.0%, 2/16/24 $ 343,690 649,209 Government National Mortgage Association, 3.0%, 8/20/38 655,267 378,339 1.43 1M LIBOR+ Government National Mortgage 20bps Association, Floating Rate Note, 1/16/33 379,140 707,178 1.48 1M LIBOR+ Government National Mortgage 25bps Association, Floating Rate Note, 1/16/35 706,271 183,231 1.91 1M LIBOR+ Government National Mortgage 68bps Association, Floating Rate Note, 10/16/39 185,234 187,421 1.63 1M LIBOR+ Government National Mortgage 40bps Association, Floating Rate Note, 10/20/38 187,933 677,704 1.48 1M LIBOR+ Government National Mortgage 25bps Association, Floating Rate Note, 2/20/35 674,284 1,332,385 1.63 1M LIBOR+ Government National Mortgage 40bps Association, Floating Rate Note, 3/16/32 1,339,012 671,202 1.73 1M LIBOR+ Government National Mortgage 50bps Association, Floating Rate Note, 4/16/30 673,796 144,876 1.78 1M LIBOR+ Government National Mortgage 55bps Association, Floating Rate Note, 4/16/32 146,624 95,150 1.63 1M LIBOR+ Government National Mortgage 40bps Association, Floating Rate Note, 5/16/38 95,181 137,525 1.73 1M LIBOR+ Government National Mortgage 50bps Association, Floating Rate Note, 6/16/31 138,118 1,454,774 1.83 1M LIBOR+ Government National Mortgage 60bps Association, Floating Rate Note, 7/20/39 1,466,452 240,312 2.23 1M LIBOR+ Government National Mortgage 100bps Association, Floating Rate Note, 8/16/39 245,802 229,973 1.73 1M LIBOR+ Government National Mortgage 50bps Association, Floating Rate Note, 8/20/38 231,287 609,511 1.76 1M LIBOR+ NCUA Guaranteed Notes Trust REMICS, 53bps Floating Rate Note, 3/9/21 (e) 608,262 -------------- $ 154,590,314 -------------- Total Government $ 154,590,314 -------------------------------------------------------------------------------------------------------------- TOTAL COLLATERALIZED MORTGAGE OBLIGATIONS (Cost $933,779,655) $ 935,394,693 -------------------------------------------------------------------------------------------------------------- CORPORATE BONDS -- 27.6% Energy -- 2.3% Oil & Gas Equipment & Services -- 0.1% 5,985,000 Schlumberger Holdings Corp., 1.9%, 12/21/17 (144A) $ 5,990,478 -------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 62 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Integrated Oil & Gas -- 1.1% 805,000 BP Capital Markets Plc, 1.674%, 2/13/18 $ 805,572 1,848,000 1.69 3M LIBOR+ BP Capital Markets Plc, Floating Rate 51bps Note, 5/10/18 1,852,959 1,013,000 1.72 3M LIBOR+ BP Capital Markets Plc, Floating Rate 54bps Note, 5/10/19 1,019,116 2,616,000 2.12 3M LIBOR+ BP Capital Markets Plc, Floating Rate 87bps Note, 9/16/21 2,658,528 1,585,000 Chevron Corp., 1.718%, 6/24/18 1,586,314 1,385,000 1.69 3M LIBOR+ Chevron Corp., Floating Rate Note, 51bps 11/16/18 1,392,586 1,195,000 1.54 3M LIBOR+ Chevron Corp., Floating Rate Note, 36bps 11/9/17 1,195,497 2,550,000 1.38 3M LIBOR+ Chevron Corp., Floating Rate Note, 17bps 3/2/18 2,551,642 3,115,000 1.43 3M LIBOR+ Chevron Corp., Floating Rate Note, 21bps 3/3/20 3,123,794 4,190,000 1.68 3M LIBOR+ Chevron Corp., Floating Rate Note, 50bps 5/16/18 4,202,892 3,611,000 1.80 3M LIBOR+ Exxon Mobil Corp., Floating Rate Note, 60bps 2/28/18 3,620,584 7,715,000 1.89 3M LIBOR+ Shell International Finance BV, Floating 58bps Rate Note, 11/10/18 7,759,044 3,132,000 1.66 3M LIBOR+ Shell International Finance BV, Floating 35bps Rate Note, 9/12/19 3,149,745 4,900,000 1.51 3M LIBOR+ Statoil ASA, Floating Rate Note, 11/9/17 20bps 4,901,150 2,555,000 1.60 3M LIBOR+ Statoil ASA, Floating Rate Note, 5/15/18 29bps 2,559,604 -------------- $ 42,379,027 -------------------------------------------------------------------------------------------------------------- Oil & Gas Exploration & Production -- 0.2% 5,170,000 Canadian Natural Resources, Ltd., 1.75%, 1/15/18 $ 5,173,664 900,000 XTO Energy, Inc., 5.5%, 6/15/18 926,142 -------------- $ 6,099,806 -------------------------------------------------------------------------------------------------------------- Oil & Gas Storage & Transportation -- 0.9% 5,065,000 Enbridge Energy Partners LP, 6.5%, 4/15/18 $ 5,190,734 1,435,000 Energy Transfer LP, 2.5%, 6/15/18 1,440,636 6,735,000 Enterprise Products Operating LLC, 1.65%, 5/7/18 6,732,605 7,390,000 Kinder Morgan Energy Partners LP, 5.95%, 2/15/18 7,498,822 2,895,000 TransCanada PipeLines, Ltd., 1.625%, 11/9/17 2,894,699 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 63 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Oil & Gas Storage & Transportation -- (continued) 3,975,000 TransCanada PipeLines, Ltd., 1.875%, 1/12/18 $ 3,978,388 5,483,000 2.09 3M LIBOR+ TransCanada PipeLines, Ltd., Floating 79bps Rate Note, 1/12/18 5,493,126 -------------- $ 33,229,010 -------------- Total Energy $ 87,698,321 -------------------------------------------------------------------------------------------------------------- MATERIALS -- 0.1% Diversified Chemicals -- 0.1% 3,235,000 1.84 3M LIBOR+ EI du Pont de Nemours & Co., Floating 53bps Rate Note, 5/1/20 $ 3,262,285 -------------- Total Materials $ 3,262,285 -------------------------------------------------------------------------------------------------------------- CAPITAL GOODS -- 0.5% Aerospace & Defense -- 0.5% 6,410,000 Northrop Grumman Corp., 1.75%, 6/1/18 $ 6,417,736 3,850,000 United Technologies Corp., 1.778%, 5/4/18 (Step) 3,851,837 6,630,000 1.66 3M LIBOR+ United Technologies Corp., Floating Rate 35bps Note, 11/1/19 6,662,756 -------------- $ 16,932,329 -------------------------------------------------------------------------------------------------------------- Industrial Conglomerates -- 0.0%+ 780,000 2.10 3M LIBOR+ General Electric Co., Floating Rate Note, 80bps 4/15/20 $ 791,624 -------------- Total Capital Goods $ 17,723,953 -------------------------------------------------------------------------------------------------------------- TRANSPORTATION -- 0.3% Railroads -- 0.2% 537,000 Burlington Northern Santa Fe LLC, 5.75%, 3/15/18 $ 547,129 1,670,000 1.35 3M LIBOR+ Canadian National Railway Co., Floating 17bps Rate Note, 11/14/17 1,670,382 1,989,000 Norfolk Southern Corp., 5.75%, 4/1/18 2,029,026 2,855,000 Union Pacific Corp., 5.7%, 8/15/18 2,953,096 -------------- $ 7,199,633 -------------------------------------------------------------------------------------------------------------- Highways & Railtracks -- 0.1% 6,550,000 ERAC USA Finance LLC, 6.375%, 10/15/17 (144A) $ 6,560,091 -------------- Total Transportation $ 13,759,724 -------------------------------------------------------------------------------------------------------------- AUTOMOBILES & COMPONENTS -- 1.5% Automobile Manufacturers -- 1.5% 2,650,000 1.79 3M LIBOR+ Daimler Finance North America LLC, 62bps Floating Rate Note, 10/30/19 (144A) $ 2,663,290 1,275,000 1.63 3M LIBOR+ Daimler Finance North America LLC, 42bps Floating Rate Note, 3/2/18 (144A) 1,276,240 The accompanying notes are an integral part of these financial statements. 64 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Automobile Manufacturers -- (continued) 5,555,000 1.63 3M LIBOR+ Daimler Finance North America LLC, 45bps Floating Rate Note, 5/18/18 (144A) $ 5,566,146 400,000 Ford Motor Credit Co LLC, 2.24%, 6/15/18 401,342 2,980,000 2.16 3M LIBOR+ Ford Motor Credit Co LLC, Floating Rate 100bps Note, 1/9/20 3,004,776 780,000 2.24 3M LIBOR+ Ford Motor Credit Co LLC, Floating Rate 93bps Note, 11/4/19 785,405 5,295,000 2.06 3M LIBOR+ Ford Motor Credit Co LLC, Floating Rate 83bps Note, 3/12/19 5,320,347 2,600,000 2.10 3M LIBOR+ Ford Motor Credit Co. LLC, Floating Rate 94bps Note, 1/9/18 2,604,799 1,000,000 2.23 3M LIBOR+ Nissan Motor Acceptance Corp., Floating 101bps Rate Note, 3/8/19 (144A) 1,011,066 3,115,000 1.95 3M LIBOR+ Nissan Motor Acceptance Corp., Floating 80bps Rate Note, 4/6/18 (144A) 3,124,952 3,530,000 1.69 3M LIBOR+ Nissan Motor Acceptance Corp., Floating 39bps Rate Note, 7/13/20 (144A) 3,532,083 2,650,000 1.76 3M LIBOR+ Nissan Motor Acceptance Corp., Floating 52bps Rate Note, 9/13/19 (144A) 2,662,752 1,970,000 1.72 3M LIBOR+ Nissan Motor Acceptance Corp., Floating 39bps Rate Note, 9/28/20 (144A) 1,973,526 3,890,000 Toyota Motor Credit Corp., 1.2%, 4/6/18 3,884,953 3,150,000 Toyota Motor Credit Corp., 1.25%, 10/5/17 3,149,982 3,063,000 1.60 3M LIBOR+ Toyota Motor Credit Corp., Floating Rate 44bps Note, 10/18/19 3,083,317 4,400,000 2.00 3M LIBOR+ Toyota Motor Credit Corp., Floating Rate 82bps Note, 2/19/19 4,446,665 3,000,000 1.60 3M LIBOR+ Toyota Motor Credit Corp., Floating Rate 37bps Note, 3/12/20 3,012,425 3,205,000 1.42 3M LIBOR+ Toyota Motor Credit Corp., Floating Rate 26bps Note, 4/17/20 3,214,599 2,501,000 1.62 3M LIBOR+ Toyota Motor Credit Corp., Floating Rate 46bps Note, 7/13/18 2,509,331 2,500,000 1.61 3M LIBOR+ Volkswagen Group of America Finance 44bps LLC, Floating Rate Note, 11/20/17 (144A) 2,501,035 -------------- $ 59,729,031 -------------- Total Automobiles & Components $ 59,729,031 -------------------------------------------------------------------------------------------------------------- MEDIA -- 0.2% Broadcasting -- 0.2% 6,795,000 1.84 3M LIBOR+ NBCUniversal Enterprise, Inc., Floating 68.5bps Rate Note, 4/15/18 (144A) $ 6,817,833 -------------- Total Media $ 6,817,833 -------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 65 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- FOOD, BEVERAGE & TOBACCO -- 0.6% Brewers -- 0.1% 3,569,000 1.57 3M LIBOR+ Anheuser-Busch InBev Finance, Inc., 40bps Floating Rate Note, 2/1/19 $ 3,583,025 -------------------------------------------------------------------------------------------------------------- Packaged Foods & Meats -- 0.2% 9,480,000 1.92 3M LIBOR+ Mondelez International Holdings 61bps Netherlands BV, Floating Rate Note, 10/28/19 (144A) $ 9,519,718 900,000 1.87 3M LIBOR+ Tyson Foods, Inc., Floating Rate Note, 55bps 6/2/20 904,281 -------------- $ 10,423,999 -------------------------------------------------------------------------------------------------------------- Tobacco -- 0.3% 3,635,000 1.90 3M LIBOR+ BAT Capital Corp., Floating Rate Note, 59bps 8/14/20 (144A) $ 3,641,529 7,406,000 Reynolds American, Inc., 2.3%, 6/12/18 7,438,546 -------------- $ 11,080,075 -------------- Total Food, Beverage & Tobacco $ 25,087,099 -------------------------------------------------------------------------------------------------------------- HEALTH CARE EQUIPMENT & SERVICES -- 0.8% Health Care Equipment -- 0.2% 3,280,000 Medtronic, Inc., 1.375%, 4/1/18 $ 3,277,671 2,680,000 2.05 3M LIBOR+ Medtronic, Inc., Floating Rate Note, 80bps 3/15/20 2,722,486 -------------- $ 6,000,157 -------------------------------------------------------------------------------------------------------------- Managed Health Care -- 0.6% 12,910,000 1.87 3M LIBOR+ Aetna, Inc., Floating Rate Note, 12/8/17 65bps $ 12,923,787 2,960,000 UnitedHealth Group, Inc., 1.4%, 12/15/17 2,959,586 7,975,000 UnitedHealth Group, Inc., 1.9%, 7/16/18 7,996,027 -------------- $ 23,879,400 -------------- Total Health Care Equipment & Services $ 29,879,557 -------------------------------------------------------------------------------------------------------------- PHARMACEUTICALS, BIOTECHNOLOGY & LIFE SCIENCES -- 1.1% Biotechnology -- 1.1% 13,253,000 AbbVie, Inc., 1.8%, 5/14/18 $ 13,271,416 3,265,000 1.50 3M LIBOR+ Amgen, Inc., Floating Rate Note, 32bps 5/10/19 3,275,646 3,305,000 1.63 3M LIBOR+ Amgen, Inc., Floating Rate Note, 45bps 5/11/20 3,321,911 3,484,000 1.77 3M LIBOR+ Amgen, Inc., Floating Rate Note, 60bps 5/22/19 3,508,499 5,900,000 2.07 3M LIBOR+ Baxalta, Inc., Floating Rate Note, 78bps 6/22/18 5,921,028 6,160,000 Biogen, Inc., 6.875%, 3/1/18 6,291,786 The accompanying notes are an integral part of these financial statements. 66 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Biotechnology -- (continued) 3,600,000 Celgene Corp., 2.125%, 8/15/18 $ 3,615,060 3,800,000 1.55 3M LIBOR+ Gilead Sciences, Inc., Floating Rate 22bps Note, 3/20/19 3,806,844 -------------- $ 43,012,190 -------------------------------------------------------------------------------------------------------------- Pharmaceuticals -- 0.0%+ 1,400,000 1.43 3M LIBOR+ Bayer US Finance LLC, Floating Rate 28bps Note, 10/6/17 (144A) $ 1,400,028 -------------- Total Pharmaceuticals, Biotechnology & Life Sciences $ 44,412,218 -------------------------------------------------------------------------------------------------------------- BANKS -- 9.6% Diversified Banks -- 7.0% 12,315,000 1.94 3M LIBOR+ ABN AMRO Bank NV, Floating Rate 64bps Note, 1/18/19 (144A) $ 12,369,900 4,505,000 1.62 3M LIBOR+ American Express Centurion Bank, 30bps Floating Rate Note, 6/15/18 4,507,942 3,115,000 Bank of America Corp., 2.0%, 1/11/18 3,118,440 3,835,000 Bank of America Corp., 6.875%, 4/25/18 3,945,387 1,715,000 2.34 3M LIBOR+ Bank of America Corp., Floating Rate 104bps Note, 1/15/19 1,731,853 3,100,000 2.47 3M LIBOR+ Bank of America Corp., Floating Rate 116bps Note, 1/20/23 3,149,922 3,897,000 2.39 3M LIBOR+ Bank of America Corp., Floating Rate 107bps Note, 3/22/18 3,913,560 6,142,000 2.17 3M LIBOR+ Bank of America Corp., Floating Rate 87bps Note, 4/1/19 6,197,247 1,525,000 1.69 3M LIBOR+ Bank of Montreal, Floating Rate Note, 44bps 6/15/20 1,528,469 2,540,000 1.81 3M LIBOR+ Bank of Montreal, Floating Rate Note, 65bps 7/18/19 2,559,193 2,665,000 1.78 3M LIBOR+ Bank of Montreal, Floating Rate Note, 61bps 7/31/18 2,676,368 3,930,000 1.80 3M LIBOR+ Banque Federative du Credit Mutuel 49bps SA, Floating Rate Note, 7/20/20 (144A) 3,937,662 3,665,000 BPCE SA, 1.625%, 1/26/18 3,664,146 2,590,000 1.84 3M LIBOR+ Caisse Centrale Desjardins, Floating 66.5bps Rate Note, 1/29/18 (144A) 2,595,113 2,610,000 1.74 3M LIBOR+ Canadian Imperial Bank of Commerce, 52bps Floating Rate Note, 9/6/19 2,621,839 3,800,000 1.58 3M LIBOR+ Citibank NA, Floating Rate Note, 26bps 9/18/19 3,802,877 1,720,000 Citigroup, Inc., 1.7%, 4/27/18 1,719,841 3,915,000 1.89 3M LIBOR+ Citigroup, Inc., Floating Rate Note, 70bps 11/24/17 3,918,407 7,015,000 1.86 3M LIBOR+ Citigroup, Inc., Floating Rate Note, 69bps 4/27/18 7,032,814 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 67 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Diversified Banks -- (continued) 4,691,000 2.88 3M LIBOR+ Citigroup, Inc., Floating Rate Note, 170bps 5/15/18 $ 4,733,981 1,500,000 2.15 3M LIBOR+ Citigroup, Inc., Floating Rate Note, 93bps 6/7/19 1,514,919 3,140,000 2.19 3M LIBOR+ Citigroup, Inc., Floating Rate Note, 88bps 7/30/18 3,156,579 3,840,000 1.86 3M LIBOR+ Citizens Bank NA, Floating Rate Note, 54bps 3/2/20 3,841,804 3,340,000 1.77 3M LIBOR+ Citizens Bank NA, Floating Rate Note, 57bps 5/26/20 3,347,014 3,675,000 1.69 3M LIBOR+ Cooperatieve Rabobank UA New York, 51bps Floating Rate Note, 8/9/19 3,700,188 11,340,000 1.90 3M LIBOR+ Danske Bank AS, Floating Rate Note, 58bps 9/6/19 (144A) 11,397,555 4,680,000 Discover Bank, 2.0%, 2/21/18 4,686,973 3,325,000 Discover Bank, 2.6%, 11/13/18 3,346,634 3,800,000 1.70 3M LIBOR+ DNB Bank ASA, Floating Rate Note, 37bps 10/2/20 (144A) 3,802,202 4,255,000 HSBC USA, Inc., 1.625%, 1/16/18 4,256,589 4,755,000 HSBC USA, Inc., 1.7%, 3/5/18 4,758,896 2,740,000 ING Bank NV, 2.0%, 11/26/18 (144A) 2,741,497 2,675,000 2.45 3M LIBOR+ ING Bank NV, Floating Rate Note, 113bps 3/22/19 (144A) 2,707,334 100,000 1.92 3M LIBOR+ ING Bank NV, Floating Rate Note, 61bps 8/15/19 (144A) 100,528 3,190,000 2.09 3M LIBOR+ ING Bank NV, Floating Rate Note, 78bps 8/17/18 (144A) 3,207,609 700,000 2.28 3M LIBOR+ ING Bank NV, Floating Rate Note, 97bps 8/17/20 (144A) 709,717 8,825,000 2.21 3M LIBOR+ JPMorgan Chase & Co., Floating Rate 90bps Note, 1/25/18 8,847,270 3,800,000 1.83 3M LIBOR+ JPMorgan Chase & Co., Floating Rate 51bps Note, 3/1/18 3,806,345 2,500,000 1.86 3M LIBOR+ JPMorgan Chase & Co., Floating Rate 55bps Note, 4/25/18 2,506,498 2,875,000 1.78 3M LIBOR+ JPMorgan Chase Bank NA, Floating Rate 45bps Note, 9/21/18 2,882,382 1,548,000 1.84 3M LIBOR+ Lloyds Bank Plc, Floating Rate Note, 52bps 3/16/18 1,550,870 6,720,000 1.86 3M LIBOR+ Lloyds Bank Plc, Floating Rate Note, 55bps 5/14/18 6,737,849 3,750,000 2.09 3M LIBOR+ Lloyds Bank Plc, Floating Rate Note, 78bps 8/17/18 3,762,880 4,941,000 1.95 3M LIBOR+ Macquarie Bank, Ltd., Floating Rate Note, 63bps 10/27/17 (144A) 4,943,115 2,800,000 2.35 3M LIBOR+ Mizuho Bank, Ltd., Floating Rate Note, 119bps 10/20/18 (144A) 2,828,064 The accompanying notes are an integral part of these financial statements. 68 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Diversified Banks -- (continued) 7,555,000 1.94 3M LIBOR+ Mizuho Bank, Ltd., Floating Rate Note, 64bps 3/26/18 (144A) $ 7,572,869 3,210,000 1.00 Mizuho Securities USA LLC, Floating Rate Note, 10/11/17 3,209,991 2,425,000 1.75 3M LIBOR+ MUFG Americas Holdings Corp., Floating 57bps Rate Note, 2/9/18 2,428,145 3,350,000 1.79 3M LIBOR+ Nordea Bank AB, Floating Rate Note, 47bps 5/29/20 (144A) 3,362,507 3,600,000 2.11 3M LIBOR+ Nordea Bank AB, Floating Rate Note, 84bps 9/17/18 (144A) 3,624,548 4,515,000 1.92 3M LIBOR+ Nordea Bank AB, Floating Rate Note, 62bps 9/30/19 (144A) 4,549,047 2,500,000 1.42 3M LIBOR+ Royal Bank of Canada, Floating Rate 26bps Note, 10/13/17 2,500,166 3,115,000 1.70 3M LIBOR+ Royal Bank of Canada, Floating Rate 38bps Note, 3/2/20 3,118,978 2,500,000 1.65 3M LIBOR+ Royal Bank of Canada, Floating Rate 48bps Note, 7/29/19 2,511,578 1,325,000 1.71 3M LIBOR+ Royal Bank of Canada, Floating Rate 54bps Note, 7/30/18 1,329,701 3,500,000 1.56 3M LIBOR+ Royal Bank of Canada, Floating Rate 24bps Note, 8/29/19 3,500,933 6,005,000 1.81 3M LIBOR+ Skandinaviska Enskilda Banken AB, 57bps Floating Rate Note, 9/13/19 (144A) 6,036,523 2,980,000 1.70 3M LIBOR+ Sumitomo Mitsui Banking Corp., Floating 54bps Rate Note, 1/11/19 2,992,528 2,975,000 1.74 3M LIBOR+ Sumitomo Mitsui Banking Corp., Floating 58bps Rate Note, 1/16/18 2,979,046 3,279,000 1.83 3M LIBOR+ Sumitomo Mitsui Banking Corp., Floating 67bps Rate Note, 10/19/18 3,294,034 3,115,000 1.73 3M LIBOR+ Sumitomo Mitsui Trust Bank, Ltd., Floating 51bps Rate Note, 3/6/19 (144A) 3,122,142 3,750,000 1.71 3M LIBOR+ Svenska Handelsbanken AB, Floating Rate 49bps Note, 9/6/19 3,767,639 5,700,000 1.68 3M LIBOR+ Svenska Handelsbanken AB, Floating Rate 36bps Note, 9/8/20 5,710,317 1,471,000 The Bank of Nova Scotia, 1.45%, 4/25/18 1,470,507 761,000 The Bank of Nova Scotia, 1.7%, 6/11/18 761,621 4,145,000 1.58 3M LIBOR+ The Toronto-Dominion Bank, Floating Rate 42bps Note, 1/18/19 4,158,057 3,860,000 1.69 3M LIBOR+ The Toronto-Dominion Bank, Floating Rate 54bps Note, 7/23/18 3,874,511 2,600,000 1.83 3M LIBOR+ The Toronto-Dominion Bank, Floating Rate 65bps Note, 8/13/19 2,620,433 3,650,000 1.56 3M LIBOR+ US Bancorp, Floating Rate Note, 4/25/19 40bps 3,664,096 1,055,000 1.58 3M LIBOR+ US Bank NA Cincinnati Ohio, Floating Rate 41bps Note, 4/26/19 1,059,510 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 69 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Diversified Banks -- (continued) 3,125,000 2.26 3M LIBOR+ Wells Fargo & Co., Floating Rate Note, 111bps 1/24/23 $ 3,178,915 3,795,000 1.99 3M LIBOR+ Wells Fargo & Co., Floating Rate Note, 68bps 1/30/20 3,834,673 6,675,000 1.78 3M LIBOR+ Wells Fargo & Co., Floating Rate Note, 63bps 4/23/18 6,696,339 -------------- $ 271,795,626 -------------------------------------------------------------------------------------------------------------- Regional Banks -- 2.6% 3,065,000 1.87 3M LIBOR+ BB&T Corp., Floating Rate Note, 71.5bps 1/15/20 $ 3,085,928 2,000,000 Branch Banking & Trust Co., 2.3%, 10/15/18 2,011,079 3,000,000 1.61 3M LIBOR+ Branch Banking & Trust Co., 45bps Floating Rate Note, 1/15/20 3,010,315 1,520,000 Capital One NA, 1.5%, 3/22/18 1,519,039 4,000,000 2.33 3M LIBOR+ Capital One NA, Floating Rate 115bps Note, 8/17/18 4,030,055 4,000,000 2.00 3M LIBOR+ Capital One NA, Floating Rate 76.5bps Note, 9/13/19 4,026,298 3,288,000 Credit Suisse AG New York NY, 1.7%, 4/27/18 3,290,589 4,215,000 Credit Suisse AG New York NY, 1.75%, 1/29/18 4,218,302 5,260,000 Fifth Third Bancorp, 4.5%, 6/1/18 5,356,644 455,000 1.88 3M LIBOR+ Fifth Third Bank Cincinnati Ohio, 59bps Floating Rate Note, 9/27/19 457,128 3,532,000 KeyBank NA Cleveland Ohio, 1.65%, 2/1/18 3,533,148 5,350,000 1.72 3M LIBOR+ KeyBank NA Cleveland Ohio, 52bps Floating Rate Note, 6/1/18 5,366,404 5,165,000 Manufacturers & Traders Trust Co., 1.45%, 3/7/18 5,164,068 1,820,000 PNC Bank NA, 1.5%, 2/23/18 1,820,135 2,730,000 PNC Bank NA, 1.6%, 6/1/18 2,731,651 3,540,000 PNC Bank NA, 1.85%, 7/20/18 3,545,555 7,630,000 1.62 3M LIBOR+ PNC Bank NA, Floating Rate 40bps Note, 12/7/18 7,654,948 4,300,000 1.62 3M LIBOR+ PNC Bank NA, Floating Rate 42bps Note, 6/1/18 4,311,739 2,032,000 SunTrust Bank, 7.25%, 3/15/18 2,081,648 6,215,000 1.70 3M LIBOR+ SunTrust Bank, Floating Rate 53bps Note, 1/31/20 6,251,835 1,105,000 UBS AG, 1.8%, 3/26/18 1,106,792 4,500,000 2.03 3M LIBOR+ UBS AG, Floating Rate 70bps Note, 3/26/18 4,513,104 The accompanying notes are an integral part of these financial statements. 70 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Regional Banks -- (continued) 2,965,000 1.47 3M LIBOR+ US Bank NA Cincinnati Ohio, 32bps Floating Rate Note, 1/24/20 $ 2,974,236 5,125,000 1.47 3M LIBOR+ US Bank NA Cincinnati Ohio, 30bps Floating Rate Note, 1/26/18 5,128,463 4,603,000 1.75 3M LIBOR+ US Bank NA Cincinnati Ohio, 58bps Floating Rate Note, 1/29/18 4,609,108 6,485,000 1.89 3M LIBOR+ Wells Fargo Bank NA, 74bps Floating Rate Note, 1/22/18 6,498,535 3,775,000 1.79 3M LIBOR+ Wells Fargo Bank NA, 60bps Floating Rate Note, 5/24/19 3,804,107 -------------- $ 102,100,853 -------------- Total Banks $ 373,896,479 -------------------------------------------------------------------------------------------------------------- DIVERSIFIED FINANCIALS -- 2.8% Multi-Sector Holdings -- 0.2% 3,600,000 1.58 3M LIBOR+ Berkshire Hathaway Finance Corp., 26bps Floating Rate Note, 8/15/19 $ 3,611,000 3,315,000 1.46 3M LIBOR+ Berkshire Hathaway, Inc., Floating 15bps Rate Note, 8/6/18 3,319,077 -------------- $ 6,930,077 -------------------------------------------------------------------------------------------------------------- Specialized Finance -- 0.1% 1,000,000 MassMutual Global Funding II, 2.1%, 8/2/18 (144A) $ 1,004,196 3,705,000 1.54 3M LIBOR+ Metropolitan Life Global Funding I, 22bps Floating Rate Note, 9/19/19 (144A) 3,707,742 -------------- $ 4,711,938 -------------------------------------------------------------------------------------------------------------- Consumer Finance -- 1.1% 1,750,000 1.88 3M LIBOR+ American Express Credit Corp., Floating 57bps Rate Note, 10/30/19 $ 1,759,448 3,115,000 1.75 3M LIBOR+ American Express Credit Corp., Floating 43bps Rate Note, 3/3/20 3,122,121 3,235,000 1.64 3M LIBOR+ American Express Credit Corp., Floating 33bps Rate Note, 5/3/19 3,243,178 4,258,000 American Honda Finance Corp., 1.55%, 12/11/17 4,259,510 1,810,000 1.46 3M LIBOR+ American Honda Finance Corp., Floating 15bps Rate Note, 1/22/19 1,811,951 2,570,000 1.54 3M LIBOR+ American Honda Finance Corp., Floating 31bps Rate Note, 12/11/17 2,571,351 2,000,000 1.65 3M LIBOR+ American Honda Finance Corp., Floating 34bps Rate Note, 2/14/20 2,009,445 2,187,000 Caterpillar Financial Services Corp., 2.45%, 9/6/18 2,203,304 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 71 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Consumer Finance -- (continued) 4,856,000 1.61 3M LIBOR+ Caterpillar Financial Services Corp., 29bps Floating Rate Note, 9/4/20 $ 4,863,925 9,320,000 3.36 3M LIBOR+ General Motors Financial Co, Inc., 206bps Floating Rate Note, 1/15/19 9,490,882 4,154,000 2.66 3M LIBOR+ General Motors Financial Co, Inc., 136bps Floating Rate Note, 4/10/18 4,175,869 2,323,000 2.63 3M LIBOR+ General Motors Financial Co, Inc., 145bps Floating Rate Note, 5/9/19 2,359,175 -------------- $ 41,870,159 -------------------------------------------------------------------------------------------------------------- Asset Management & Custody Banks -- 0.6% 3,190,000 State Street Corp., 4.956%, 3/15/18 $ 3,234,806 3,000,000 2.22 3M LIBOR+ State Street Corp., Floating Rate 90bps Note, 8/18/20 3,061,063 3,405,000 The Bank of New York Mellon Corp., 1.35%, 3/6/18 3,403,896 7,585,000 The Bank of New York Mellon Corp., 1.6%, 5/22/18 7,591,328 1,090,000 1.66 3M LIBOR+ The Bank of New York Mellon Corp., 44bps Floating Rate Note, 3/6/18 1,092,158 1,047,000 1.73 3M LIBOR+ The Bank of New York Mellon Corp., 56bps Floating Rate Note, 8/1/18 1,051,761 3,415,000 The Charles Schwab Corp., 1.5%, 3/10/18 3,416,130 -------------- $ 22,851,142 -------------------------------------------------------------------------------------------------------------- Investment Banking & Brokerage -- 0.8% 3,130,000 2.00 3M LIBOR+ Morgan Stanley, Floating Rate 85bps Note, 1/24/19 $ 3,151,483 4,325,000 2.04 3M LIBOR+ Morgan Stanley, Floating Rate 74bps Note, 1/5/18 4,331,434 7,360,000 2.54 3M LIBOR+ Morgan Stanley, Floating Rate Note, 2/1/19 137.5bps 7,464,812 2,800,000 1.36 3M LIBOR+ Svensk Exportkredit AB, Floating Rate 18bps Note, 11/10/17 2,800,718 2,836,000 The Charles Schwab Corp., 2.2%, 7/25/18 2,849,742 2,703,000 2.17 3M LIBOR+ The Goldman Sachs Group, Inc., Floating 102bps Rate Note, 10/23/19 2,736,285 3,325,000 2.42 3M LIBOR+ The Goldman Sachs Group, Inc., Floating 110bps Rate Note, 11/15/18 3,355,826 1,827,000 2.12 3M LIBOR+ The Goldman Sachs Group, Inc., Floating 80bps Rate Note, 12/15/17 1,829,353 3,470,000 2.51 3M LIBOR+ The Goldman Sachs Group, Inc., Floating 120bps Rate Note, 4/30/18 3,490,479 -------------- $ 32,010,132 -------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 72 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Specialized Finance -- 0.0%+ 700,000 1.57 3M LIBOR+ Moody's Corp., Floating Rate 35bps Note, 9/4/18 $ 701,235 -------------- Total Diversified Financials $ 109,074,683 -------------------------------------------------------------------------------------------------------------- INSURANCE -- 5.5% Life & Health Insurance -- 0.9% 5,215,000 1.78 3M LIBOR+ AIG Global Funding, Floating Rate 48bps Note, 7/2/20 (144A) $ 5,223,180 2,065,000 Jackson National Life Global Funding, 4.7%, 6/1/18 (144A) 2,104,946 5,159,000 1.88 3M LIBOR+ Jackson National Life Global Funding, 58bps Floating Rate Note, 10/13/17 (144A) 5,159,548 2,940,000 1.70 3M LIBOR+ Metropolitan Life Global Funding I, 43bps Floating Rate Note, 12/19/18 (144A) 2,954,134 700,000 1.79 3M LIBOR+ Pricoa Global Funding I, Floating Rate 50bps Note, 6/27/18 (144A) 702,187 7,370,000 1.70 3M LIBOR+ Principal Life Global Funding II, Floating 50bps Rate Note, 12/1/17 (144A) 7,375,411 2,481,000 1.47 3M LIBOR+ Principal Life Global Funding II, Floating 30bps Rate Note, 5/21/18 (144A) 2,484,733 3,457,000 1.87 3M LIBOR+ Protective Life Global Funding, Floating 55bps Rate Note, 6/8/18 (144A) 3,468,072 5,450,000 2.10 3M LIBOR+ Prudential Financial, Inc., Floating Rate 78bps Note, 8/15/18 5,481,792 -------------- $ 34,954,003 -------------------------------------------------------------------------------------------------------------- Multi-line Insurance -- 0.7% 5,688,000 American International Group, Inc., 5.85%, 1/16/18 $ 5,752,879 5,090,000 1.64 3M LIBOR+ Metropolitan Life Global Funding I, 40bps Floating Rate Note, 6/12/20 (144A) 5,113,735 1,695,000 New York Life Global Funding, 1.3%, 10/30/17 (144A) 1,695,028 3,143,000 New York Life Global Funding, 1.45%, 12/15/17 (144A) 3,142,544 4,204,000 1.70 3M LIBOR+ New York Life Global Funding, Floating 39bps Rate Note, 10/24/19 (144A) 4,226,117 8,050,000 1.53 3M LIBOR+ New York Life Global Funding, Floating 28bps Rate Note, 12/15/17 (144A) 8,054,155 1,250,000 1.48 3M LIBOR+ New York Life Global Funding, Floating 18bps Rate Note, 7/6/18 (144A) 1,251,274 -------------- $ 29,235,732 -------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 73 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Reinsurance -- 3.9% 1,500,000 Ailsa Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 6/15/18 (d)(e)(f) $ 1,448,850 2,500,000 5.90 T-BILL 3MO+ Alamo Re, Ltd., Floating Rate Note, 481bps 6/7/18 (Cat Bond) (144A) 2,511,750 2,000,000 0.50 T-BILL 3MO+ Alamo Re, Ltd., Floating Rate Note, 375bps 6/8/20 (Cat Bond) (144A) 2,016,400 1,500,000 Aozora Re Ltd 2017-A, Floating Rate Note, 4/7/21 (Cat Bond) (144A) 1,505,850 500,000 3.49 6M LIBOR+ Aozora Re, Ltd., Floating Rate Note, 200bps 4/7/23 (Cat Bond) (144A) 505,250 500,000 Arlington Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 8/31/16 (d)(e)(f) 24,300 750,000 Arlington Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 8/31/17 (d)(e)(f) 97,875 1,500,000 4.49 3M LIBOR+ Atlas IX Capital DAC, Floating Rate Note, 325bps 1/17/19 (Cat Bond) (144A) 1,521,000 1,250,000 Berwick 2016-1 Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 2/1/18 (d)(e)(f) 59,375 1,250,000 Berwick Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 2/1/19 (d)(e)(f) 1,192,125 2,650,000 4.86 6M LIBOR+ Bonanza Re, Ltd., Floating Rate Note, 375bps 12/31/19 (Cat Bond) (144A) 2,474,305 750,000 4.47 6M LIBOR+ Bosphorus, Ltd., Floating Rate Note, 325bps 8/17/18 (Cat Bond) (144A) 754,950 2,250,000 5.85 T-BILL 3MO+ Caelus Re IV, Ltd., Floating Rate Note, 549bps 3/6/20 (Cat Bond) (144A) 2,344,050 1,000,000 4.00 T-BILL 3MO+ Caelus Re V, Ltd., Floating Rate Note, 325bps 6/5/20 (Cat Bond) (144A) 1,006,600 1,250,000 5.46 T-BILL 3MO+ Caelus Re V, Ltd., Floating Rate Note, 450bps 6/5/20 (Cat Bond) (144A) 1,277,625 750,000 Carnoustie 2016-N,Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 11/30/20 (d)(e)(f) 81,150 2,000,000 Carnoustie Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 11/30/21 (d)(e)(f) 1,670,800 2,500,000 4.74 Casablanca Re, Variable Rate Notes, 6/4/20 (Cat Bond) 2,494,250 2,500,000 3.05 6M LIBOR+ Cranberry Re, Ltd., Floating Rate Note, 200bps 7/13/20 (Cat Bond) (144A) 2,511,250 1,000,000 3.80 T-BILL 3MO+ Cranberry Re, Ltd., Floating Rate Note, 390bps 7/6/18 (Cat Bond) (144A) 1,024,300 1,000,000 Cypress Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 1/10/18 (d)(e)(f) 862,100 The accompanying notes are an integral part of these financial statements. 74 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Reinsurance -- (continued) 2,500,000 Denning Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 7/13/18 (d)(e)(f) $ 2,476,000 2,000,000 3.69 T-BILL 3MO+ East Lane Re VI, Ltd., Floating Rate Note, 265bps 3/14/18 (Cat Bond) (144A) 2,009,000 1,274,130 Eden Re II, Ltd., Variable Rate Notes, 3/22/21 (d)(e)(f) 1,267,759 1,750,000 Eden Re II, Ltd., Variable Rate Notes, 3/22/21 (d)(e)(f) 1,741,250 1,131 Eden Re II, Variable Rate Notes, 4/23/19 (d)(e)(f) 90,664 500,000 4.80 6M LIBOR+ Fortius Re II, Ltd., Floating Rate Note, 375bps 7/7/21 (Cat Bond) (144A) 501,900 2,900,000 5.48 6M LIBOR+ Galilei Re, Ltd., Floating Rate Note, 450bps 1/8/20 (Cat Bond) (144A) 2,907,830 1,500,000 7.38 6M LIBOR+ Galilei Re, Ltd., Floating Rate Note, 625bps 1/8/20 (Cat Bond) (144A) 1,404,750 2,500,000 6.38 6M LIBOR+ Galilei Re, Ltd., Floating Rate Note, 525bps 1/8/20 (Cat Bond) (144A) 2,427,000 1,250,000 5.65 6M LIBOR+ Galilei Re, Ltd., Floating Rate Note, 450bps 1/8/21 (Cat Bond) (144A) 1,251,375 1,250,000 7.40 6M LIBOR+ Galilei Re, Ltd., Floating Rate Note, 625bps 1/8/21 (Cat Bond) (144A) 1,144,500 2,000,000 6.40 6M LIBOR+ Galilei Re, Ltd., Floating Rate Note, 525bps 1/8/21 (Cat Bond) (144A) 1,917,200 175,000 1.54 T-BILL 3MO+ Gator Re, Ltd., Floating Rate Note, 50bps 1/9/20 (Cat Bond) (144A) 2 1,300,000 Gleneagles Segregated Account (Artex SAC Ltd), Variable Rate Notes, 11/30/20 (d)(e)(f) 152,360 2,650,000 3.31 T-BILL 3MO+ Golden State Re II, Ltd., Floating Rate 220bps Note, 1/8/19 (Cat Bond) (144A) 2,647,880 2,600,000 Gullane Segregated Account (Artex SAC Ltd.), Variable Rate Note 11/30/20 (d)(e)(f) 56,680 3,000,000 Gullane Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 11/30/21 (d)(e)(f) 2,940,600 500,000 5.05 6M LIBOR+ Integrity Re, Ltd., Floating Rate Note, 400bps 6/10/20 (Cat Bond) (144A) 478,050 2,500,000 4.30 6M LIBOR+ Integrity Re, Ltd., Floating Rate Note, 325bps 6/10/20 (Cat Bond) (144A) 2,488,500 400,000 6.97 1M LIBOR+ International Bank for Reconstruction & 590bps Development, Floating Rate Note, 12/20/19 (Cat Bond) (144A) 399,988 1,250,000 7.86 International Bank for Reconstruction & Development, Floating Rate Note, 7/15/20 (Cat Bond) (144A) 1,249,588 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 75 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Reinsurance -- (continued) 1,000,000 5.57 1M LIBOR+ International Bank for Reconstruction & 450bps Development, Floating Rate Note, 8/11/20 (Cat Bond) (144A) $ 30,900 3,000,000 7.15 6M LIBOR+ Kilimanjaro II Re, Ltd., Floating Rate 600bps Note, 4/20/21 (Cat Bond) (144A) 2,851,200 1,700,000 8.67 6M LIBOR+ Kilimanjaro II Re, Ltd., Floating Rate 750bps Note, 4/21/22 (Cat Bond) (144A) 1,476,110 2,350,000 4.76 T-BILL 3MO+ Kilimanjaro Re, Ltd., Floating Rate 375bps Note, 11/25/19 (Cat Bond) (144A) 2,376,790 2,500,000 7.25 T-BILL 3MO+ Kilimanjaro Re, Ltd., Floating Rate Note, 675bps 12/6/19 (Cat Bond) (144A) 2,521,500 2,000,000 9.95 T-BILL 3MO+ Kilimanjaro Re, Ltd., Floating Rate Note, 925bps 12/6/19 (Cat Bond) (144A) 1,947,000 3,300,000 5.76 T-BILL 3MO+ Kilimanjaro Re, Ltd., Floating Rate Note, 475bps 4/30/18 (Cat Bond) (144A) 3,291,750 1,000,000 5.51 T-BILL 3MO+ Kilimanjaro Re, Ltd., Floating Rate Note, 450bps 4/30/18 (Cat Bond) (144A) 910,700 1,500,000 Kingsbarn Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 5/15/18 (d)(e)(f) 1,463,400 1,800,000 3.25 T-BILL 3MO+ Kizuna Re II, Ltd., Floating Rate Note, 225bps 4/6/18 (Cat Bond) (144A) 1,797,300 1,600,000 Lahinch Re, Variable Rate Notes, 5/10/22 (d)(e)(f) 1,584,960 500,000 Limestone Re, Ltd., Variable Rate Notes, 8/31/21 (Cat Bond) (f) 443,550 850,000 Limestone Re, Ltd., Variable Rate Notes, 8/31/21 (Cat Bond) (f) 754,035 4,000,000 4.05 ZERO+ Long Point Re III, Ltd., Floating Rate Note, 350bps 5/23/18 (Cat Bond) (144A) 4,010,400 2,500,000 Lorenz Re, Ltd., Variable Rate Notes, 3/31/19 (d)(e)(f) 140,000 2,500,000 Lorenz Re, Variable Rate Notes, 3/31/20 (d)(e)(f) 2,355,500 2,000,000 Madison Re, Variable Rate Notes, 12/31/19 (d)(e)(f) 1,645,800 2,500,000 Madison Re, Variable Rate Notes, 3/31/19 (d)(e)(f) 158,750 2,600,000 4.81 T-BILL 3MO+ MetroCat Re, Ltd., Floating Rate Note, 370bps 5/8/20 (Cat Bond) (144A) 2,628,600 2,500,000 3.25 6M LIBOR+ Nakama Re, Ltd., Floating Rate Note, 220bps 10/13/21 (Cat Bond) (144A) 2,541,000 1,000,000 N/A T-BILL 3MO+ Northshore Re II, Ltd., Floating Rate 725bps Note, 7/6/20 (Cat Bond) (144A) 1,004,700 500,000 Oakmont Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 4/13/18 (d)(e)(f) 360,000 The accompanying notes are an integral part of these financial statements. 76 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Reinsurance -- (continued) 2,000,000 Pangaea 2017 Re, Variable Rate Notes, 11/30/21 (d)(e)(f) $ 1,911,600 1,500,000 Pangaea 2017 Re, Variable Rate Notes, 5/31/22 (d)(e)(f) 1,365,600 2,500,000 Pangaea Re, Series 2015-1, Principal at Risk Notes, 2/1/19 (d)(e)(f) 11,250 2,800,000 Pangaea Re, Series 2015-2, Principal at Risk Notes, 11/30/19 (d)(e)(f) 29,120 1,500,000 Pangaea Re, Series 2016-2, Principal at Risk Notes, 11/30/20 (d)(e)(f) 98,700 2,500,000 Pangaea Re., Variable Rate Notes, 2/1/20 (d)(e)(f) 165,250 3,500,000 5.15 T-BILL 3MO+ PennUnion Re, Ltd., Floating Rate Note, 450bps 12/7/18 (Cat Bond) (144A) 3,505,600 3,000,000 Pinehurst Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 1/16/18 (d)(e)(f) 2,956,800 800,000 Portrush Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 6/15/18 (d)(e)(f) 601,280 1,500,000 6.73 T-BILL 3MO+ Queen Street X Re, Ltd., Floating Rate 575bps Note, 6/8/18 (Cat Bond) (144A) 1,507,800 1,750,000 7.13 T-BILL 3MO+ Queen Street XI Re Dac, Floating Rate 615bps Note, 6/7/19 (Cat Bond) (144A) 1,770,475 750,000 4.59 T-BILL 3MO+ Residential Reinsurance 2014, Ltd., 356bps Floating Rate Note, 6/6/18 (Cat Bond) (144A) 753,525 1,000,000 7.98 T-BILL 3MO+ Residential Reinsurance 2015, Ltd., 695bps Floating Rate Note, 12/6/19 (Cat Bond) (144A) 1,020,000 2,000,000 4.96 T-BILL 3MO+ Residential Reinsurance 2016, Ltd., 393bps Floating Rate Note, 12/6/23 (Cat Bond) (144A) 1,981,400 250,000 0.00 Residential Reinsurance 2016, Ltd., Variable Rate Notes, 12/6/20 (Cat Bond) (144A) 241,725 2,100,000 4.03 T-BILL 3MO+ Residential Reinsurance 2017, Ltd., 300bps Floating Rate Note, 6/6/21 (Cat Bond) (144A) 2,086,560 2,500,000 0.00 Resilience Re, Ltd., Variable Rate Notes, 1/12/18 (d)(e)(f) 2,363,250 1,500,000 4.50 Resilience Re, Ltd., Variable Rate Notes, 1/9/19 (d)(e)(f) 1,500,000 2,500,000 3.30 Resilience Re, Ltd., Variable Rate Notes, 1/9/19 (d)(e)(f) 2,500,000 2,000,000 0.00 Resilience Re, Ltd., Variable Rate Notes, 4/7/18 (d)(e)(f) 1,766,200 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 77 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Reinsurance -- (continued) 1,500,000 0.00 Resilience Re, Ltd., Variable Rate Notes, 6/4/18 (d)(e)(f) $ 1,461,750 2,500,000 0.00 Resilience Re, Ltd., Variable Rate Notes, 9/30/17 (d)(e)(f) 53,750 3,000,000 4.01 QTRLY T-BILL+ Sanders Re, Ltd., Floating Rate Note, 296bps 5/25/18 (Cat Bond) (144A) 3,029,100 2,369 Sector Re V, Ltd., Variable Rate Notes, 12/1/20 (144A) (d)(e)(f) 14,588 500,000 Sector Re V, Ltd., Variable Rate Notes, 12/1/21 (144A) (d)(e)(f) 403,150 2,018 Sector Re V, Ltd., Variable Rate Notes, 3/1/21 (d)(e)(f) 102,848 1,250,000 Sector Re V, Ltd., Variable Rate Notes, 3/1/22 (144A) (d)(e)(f) 901,000 2,500,000 Shinnecock Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 6/15/18 (d)(e)(f) 2,150,000 1,000,000 Silverton Re, Ltd., Variable Rate Notes, 9/18/18 (144A) (d)(e)(f) 28,000 1,000,000 Silverton Re, Ltd., Variable Rate Notes, 9/18/19 (144A) (d)(e)(f) 910,600 2,500,000 3.03 Skyline Re, Ltd., Floating Rate Note, 1/6/20 (Cat Bond) (144A) 2,482,500 1,250,000 St Andrews Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 2/1/19 (d)(e)(f) 1,212,625 1,737,984 St. Andrews Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 6/1/19 (d)(e)(f) 1,594,774 1,250,000 St. Andrews Segregated Account (Artex SAC Ltd.), Variance Rate Notes, 2/1/18 (d)(e)(f) 175,750 1,000,000 Sunningdale Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 1/16/18 (d)(e)(f) 972,100 750,000 6.01 ZERO+ Tradewynd Re, Ltd., Floating Rate Note, 540bps 1/8/18 (Cat Bond) (144A) 737,625 250,000 8.58 T-BILL 3MO+ Tramline Re II, Ltd., Floating Rate Note, 825bps 1/4/19 (Cat Bond) (144A) 247,300 1,800,000 4.68 ZERO+ Ursa Re, Ltd., Floating Rate Note, 400bps 12/10/19 (Cat Bond) (144A) 1,808,640 2,000,000 3.50 ZERO+ Ursa Re, Ltd., Floating Rate Note, 350bps 5/27/20 (Cat Bond) (144A) 2,001,200 2,700,000 Versutus 2016, Class A-1, Variable Rate Notes, 11/30/20 (d)(e)(f) 115,020 2,600,000 Versutus 2017 Class A, Variable Rate Notes, 11/30/21 (d)(e)(f) 2,574,520 The accompanying notes are an integral part of these financial statements. 78 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Reinsurance -- (continued) 3,800,000 2.01 T-BILL 3MO+ Vitality Re V, Ltd., Floating Rate Note, 175bps 1/7/19 (Cat Bond) (144A) $ 3,796,200 2,000,000 2.47 T-BILL 3MO+ Vitality Re VII, Ltd., Floating Rate Note, 215bps 1/7/20 (Cat Bond) (144A) 2,015,600 1,000,000 3.15 T-BILL 3MO+ Vitality Re VII, Ltd., Floating Rate Note, 265bps 1/7/20 (Cat Bond) (144A) 1,015,100 -------------- $ 151,170,851 -------------- Total Insurance $ 215,360,586 -------------------------------------------------------------------------------------------------------------- REAL ESTATE -- 0.1% Residential REIT -- 0.1% 5,685,000 UDR, Inc., 4.25%, 6/1/18 $ 5,774,040 -------------- Total Real Estate $ 5,774,040 -------------------------------------------------------------------------------------------------------------- SOFTWARE & SERVICES -- 0.1% Data Processing & Outsourced Services -- 0.0%+ 1,245,000 Visa, Inc., 1.2%, 12/14/17 $ 1,245,429 -------------------------------------------------------------------------------------------------------------- Systems Software -- 0.1% 2,910,000 Oracle Corp., 1.2%, 10/15/17 $ 2,909,651 -------------- Total Software & Services $ 4,155,080 -------------------------------------------------------------------------------------------------------------- TECHNOLOGY HARDWARE & EQUIPMENT -- 0.1% Computer Hardware Storage & Peripherals -- 0.1% 2,650,000 2.13 3M LIBOR+ Apple, Inc., Floating Rate Note, 2/22/19 82bps $ 2,678,863 -------------- Total Technology Hardware & Equipment $ 2,678,863 -------------------------------------------------------------------------------------------------------------- SEMICONDUCTORS & SEMICONDUCTOR EQUIPMENT -- 0.1% Semiconductors -- 0.1% 1,845,000 Altera Corp., 2.5%, 11/15/18 $ 1,863,822 3,335,000 1.68 3M LIBOR+ QUALCOMM, Inc., Floating Rate Note, 36bps 5/20/19 3,347,819 -------------- $ 5,211,641 -------------- Total Semiconductors & Semiconductor Equipment $ 5,211,641 -------------------------------------------------------------------------------------------------------------- TELECOMMUNICATION SERVICES -- 0.3% Integrated Telecommunication Services -- 0.3% 2,560,000 AT&T, Inc., 1.4%, 12/1/17 $ 2,559,642 2,550,000 2.11 3M LIBOR+ AT&T, Inc., Floating Rate Note, 11/27/18 91bps 2,570,273 2,400,000 1.90 3M LIBOR+ AT&T, Inc., Floating Rate Note, 3/11/19 67bps 2,411,816 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 79 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Integrated Telecommunication Services -- (continued) 2,990,000 1.74 3M LIBOR+ Deutsche Telekom International Finance 58bps BV, Floating Rate Note, 1/17/20 (144A) $ 2,999,379 -------------- $ 10,541,110 -------------- Total Telecommunication Services $ 10,541,110 -------------------------------------------------------------------------------------------------------------- UTILITIES -- 1.5% Electric Utilities -- 1.1% 2,655,000 American Electric Power Co., Inc., 1.65%, 12/15/17 $ 2,655,145 1,631,000 Commonwealth Edison Co., 5.8%, 3/15/18 1,661,863 1,147,000 Duke Energy Corp., 2.1%, 6/15/18 1,150,383 7,095,000 1.37 3M LIBOR+ Duke Energy Progress LLC, Floating Rate 20bps Note, 11/20/17 7,097,263 4,967,000 1.50 3M LIBOR+ Duke Energy Progress LLC, Floating Rate 18bps Note, 9/8/20 4,969,901 4,163,000 Eversource Energy, 1.45%, 5/1/18 4,161,509 3,795,000 NextEra Energy Capital Holdings, Inc., 1.649%, 9/1/18 3,793,344 2,335,000 Ohio Power Co., 6.05%, 5/1/18 2,393,793 6,145,000 PECO Energy Co., 5.35%, 3/1/18 6,241,077 9,201,000 PPL Capital Funding, Inc., 1.9%, 6/1/18 9,205,317 600,000 Southwestern Electric Power Co., 5.875%, 3/1/18 610,333 -------------- $ 43,939,928 -------------------------------------------------------------------------------------------------------------- Gas Utilities -- 0.1% 3,754,000 Kinder Morgan Finance Co LLC, 6.0%, 1/15/18 (144A) $ 3,795,729 1,501,000 Panhandle Eastern Pipe Line Co LP, 7.0%, 6/15/18 1,552,166 -------------- $ 5,347,895 -------------------------------------------------------------------------------------------------------------- Multi-Utilities -- 0.3% 1,750,000 Dominion Energy, Inc., 1.6%, 8/15/19 $ 1,738,726 2,500,000 Dominion Energy, Inc., 1.875%, 1/15/19 2,496,837 5,643,000 Dominion Energy, Inc., 1.9%, 6/15/18 5,652,182 -------------- $ 9,887,745 -------------- Total Utilities $ 59,175,568 -------------------------------------------------------------------------------------------------------------- TOTAL CORPORATE BONDS (Cost $1,076,417,432) $1,074,238,071 -------------------------------------------------------------------------------------------------------------- U.S. GOVERNMENT AND AGENCY OBLIGATIONS -- 9.4% 10,000,000 Fannie Mae Discount Notes 10/2/17 (c) $ 10,000,000 14,276 3.33 US0012M+ Fannie Mae, Floating Rate Note, 1/1/48 168bps 15,072 The accompanying notes are an integral part of these financial statements. 80 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- U.S. GOVERNMENT AND AGENCY OBLIGATIONS -- (continued) 8,408 2.99 H15T1Y+ Fannie Mae, Floating Rate Note, 10/1/32 219.1bps $ 8,599 2,975 2.69 H15T1Y+ Fannie Mae, Floating Rate Note, 11/1/23 200.2bps 3,075 21,103 2.92 H15T1Y+ Fannie Mae, Floating Rate Note, 2/1/34 217bps 21,247 12,867 3.30 H15T1Y+ Fannie Mae, Floating Rate Note, 9/1/32 211.3bps 13,477 2,645,000 1.29 USBMMY3M+ Federal Farm Credit Banks, Floating Rate 23bps Note, 10/17/17 2,645,322 3,149 3.18 H15T1Y+ Federal Home Loan Mortgage Corp., 229.2bps Floating Rate Note, 10/1/23 3,227 12,864 3.50 Federal Home Loan Mortgage Corp., Floating Rate Note, 11/1/33 13,366 5,202 3.12 H15T3Y+ Federal Home Loan Mortgage Corp., 212.1bps Floating Rate Note, 6/1/35 5,204 5,690 2.38 H15T1Y+ Government National Mortgage 150bps Association II, Floating Rate Note, 1/20/22 5,814 45,275,000 1.32 USBMMY3M+ U.S. Treasury Note, Floating Rate Note, 27.2bps 1/31/18 45,317,216 46,790,000 1.19 USBMMY3M+ U.S. Treasury Note, Floating Rate Note, 14bps 1/31/19 46,865,069 45,510,000 1.22 USBMMY3M+ U.S. Treasury Note, Floating Rate Note, 17bps 10/31/18 45,581,520 45,075,000 1.24 USBMMY3M+ U.S. Treasury Note, Floating Rate Note, 19bps 4/30/18 45,126,445 47,285,000 1.12 USBMMY3M+ U.S. Treasury Note, Floating Rate Note, 7bps 4/30/19 47,312,059 45,595,000 1.22 USBMMY3M+ U.S. Treasury Note, Floating Rate Note, 17.4bps 7/31/18 45,662,960 28,890,000 1.11 USBMMY3M+ U.S. Treasury Note, Floating Rate Note, 6bps 7/31/19 28,891,270 47,480,000 1.22 USBMMY3M+ U.S. Treasury Note, Floating Rate Note, 16.8bps 10/31/17 47,486,356 2,550,000 U.S. Treasury Notes, 0.625%, 11/30/17 2,548,041 -------------- $ 367,525,339 -------------------------------------------------------------------------------------------------------------- TOTAL U.S. GOVERNMENT AND AGENCY OBLIGATIONS (Cost $367,403,477) $ 367,525,339 -------------------------------------------------------------------------------------------------------------- MUNICIPAL BOND -- 0.0%+ Municipal Student Loan -- 0.0%+ 475,210 2.06 3M LIBOR+ Louisiana Public Facilities Authority, 74bps Floating Rate Note, 4/26/27 $ 474,811 -------------------------------------------------------------------------------------------------------------- TOTAL MUNICIPAL BOND (Cost $477,125) $ 474,811 -------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 81 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- SENIOR FLOATING RATE LOAN INTERESTS -- 4.7%** ENERGY -- 0.0%+ Oil & Gas Storage & Transportation -- 0.0%+ 1,000,000 3.98 LIBOR+ Energy Transfer Equity LP, Loan, 275bps 2/2/24 $ 1,005,536 897,278 6.59 LIBOR+ Gulf Finance LLC, Tranche B Term Loan, 525bps 8/17/23 848,489 -------------- $ 1,854,025 -------------- Total Energy $ 1,854,025 -------------------------------------------------------------------------------------------------------------- MATERIALS -- 0.2% Diversified Chemicals -- 0.1% 916,716 4.12 LIBOR+ Tata Chemicals North America, Inc., Term 275bps Loan, 8/7/20 $ 923,018 315,814 3.74 LIBOR+ The Chemours Co., Tranche B-1 US Term 250bps Loan, 5/12/22 317,985 385,465 0.00 LIBOR+ Tronox Blocked Borrower LLC, Blocked 300bps Dollar Term Loan (First Lien), 9/14/24 387,362 889,535 0.00 LIBOR+ Tronox Finance LLC, Initial Dollar Term 300bps Loan (First Lien), 9/14/24 893,913 -------------- $ 2,522,278 -------------------------------------------------------------------------------------------------------------- Specialty Chemicals -- 0.1% 794,875 3.33 LIBOR+ Axalta Coating Systems US Holdings, Inc., 200bps Term B-2 Dollar Loan, 6/30/24 $ 799,801 245,627 3.23 LIBOR+ PolyOne Corp., Term B-3 Loan, 11/12/22 200bps 247,315 406,021 4.56 LIBOR+ PQ Corp., Second Amendment Tranche B-1 325bps Term Loan, 11/4/22 410,299 473,757 3.31 LIBOR+ WR Grace & Co-Conn, U.S. Term Loan, 200bps 1/23/21 475,885 -------------- $ 1,933,300 -------------------------------------------------------------------------------------------------------------- Construction Materials -- 0.0%+ 349,125 5.08 LIBOR+ Unifrax I LLC, Term Loan (First Lien), 375bps 3/30/24 $ 352,289 -------------------------------------------------------------------------------------------------------------- Diversified Metals & Mining -- 0.0%+ 495,000 4.50 LIBOR+ Global Brass And Copper Inc., Initial Term 325bps Loan, 6/30/23 $ 499,331 -------------------------------------------------------------------------------------------------------------- Steel -- 0.0%+ 493,769 4.07 LIBOR+ Zekelman Industries, Inc., Term Loan, 275bps 6/8/21 $ 496,238 -------------- Total Materials $ 5,803,436 -------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 82 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- CAPITAL GOODS -- 0.4% Aerospace & Defense -- 0.2% 2,500,000 0.00 LIBOR+ MacDonald, Dettwiler and Associates, 275bps Ltd., Term Loan B, 7/5/24 $ 2,504,240 1,407,550 3.98 LIBOR+ DigitalGlobe, Inc., Term Loan, 275bps 12/22/23 1,408,723 694,750 3.25 LIBOR+ Leidos Innovations Corp., B Term Loan, 200bps 6/9/23 698,050 1,208,150 6.08 LIBOR+ The SI Organization, Inc., Term Loan (First 475bps Lien), 11/19/19 1,226,461 748,106 4.27 LIBOR+ TransDigm, Inc., Tranche F Term Loan, 300bps 6/9/23 750,911 1,254,448 4.26 LIBOR+ TransDigm, Inc., Tranche G Term Loan, 300bps 8/16/24 1,258,108 -------------- $ 7,846,493 -------------------------------------------------------------------------------------------------------------- Building Products -- 0.1% 950,525 4.02 LIBOR+ Armstrong World Industries, Inc., Term 275bps Loan B, 2/23/23 $ 955,872 687,750 3.99 LIBOR+ Beacon Roofing Supply, Inc., Initial Term 275bps Loan, 9/25/22 691,117 612,187 3.98 LIBOR+ Quikrete Holdings, Inc., Initial Loan (First 275bps Lien), 11/3/23 612,187 -------------- $ 2,259,176 -------------------------------------------------------------------------------------------------------------- Electrical Components & Equipment -- 0.1% 1,290,266 3.74 LIBOR+ Dell International LLC, New Term B Loan, 250bps 9/7/23 $ 1,295,967 472,625 4.00 LIBOR+ Diebold Nixdorf, Inc., New Dollar Term B 275bps Loan, 11/6/23 473,609 1,536,873 3.74 LIBOR+ Southwire Co., Term Loan, 1/31/21 250bps 1,545,198 660,104 6.82 LIBOR+ WireCo WorldGroup, Inc., Initial Term Loan 550bps (First Lien), 7/22/23 668,025 -------------- $ 3,982,799 -------------------------------------------------------------------------------------------------------------- Industrial Conglomerates -- 0.0%+ 222,542 4.79 LIBOR+ AVSC Holding Corp., New Term Loan (First 350bps Lien), 4/25/24 $ 222,542 449,597 4.24 LIBOR+ Milacron LLC, Term B Loan, 9/25/23 300bps 452,313 -------------- $ 674,855 -------------------------------------------------------------------------------------------------------------- Construction & Farm Machinery & Heavy Trucks -- 0.0%+ 199,000 4.08 LIBOR+ Clark Equipment Co., Tranche B Term 275bps Loan, 5/11/24 $ 200,389 301,078 3.58 LIBOR+ Terex Corp., Incremental U.S. Term Loan, 225bps 1/31/24 301,580 -------------- $ 501,969 -------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 83 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Industrial Machinery -- 0.0%+ 195,089 4.08 LIBOR+ Gardner Denver, Inc., Tranche B-1 Dollar 275bps Term Loan, 7/30/24 $ 195,466 1,732,008 5.48 LIBOR+ NN, Inc., Tranche B Term Loan, 425bps 10/19/22 1,735,255 -------------- $ 1,930,721 -------------------------------------------------------------------------------------------------------------- Trading Companies & Distributors -- 0.0%+ 181,687 4.34 LIBOR+ WESCO Distribution, Inc., Tranche B-1 250bps Loan, 12/12/19 $ 182,482 -------------- Total Capital Goods $ 17,378,495 -------------------------------------------------------------------------------------------------------------- COMMERCIAL SERVICES & SUPPLIES -- 0.2% Commercial Printing -- 0.1% 2,000,000 0.00 LIBOR+ Multi-Color Corp., Term Loan B, 225bps 9/20/24 $ 2,010,000 -------------------------------------------------------------------------------------------------------------- Environmental & Facilities Services -- 0.0%+ 498,750 3.24 LIBOR+ Clean Harbors, Inc., Initial Term Loan, 200bps 6/28/24 $ 500,828 75,426 0.00 LIBOR+ Wrangler Buyer Corp., 9/20/24 300bps 75,850 -------------- $ 576,678 -------------------------------------------------------------------------------------------------------------- Office Services & Supplies -- 0.0%+ 459,199 3.74 LIBOR+ West Corp., Refinanced Term B-12 250bps Loan, 6/17/23 $ 459,486 -------------------------------------------------------------------------------------------------------------- Diversified Support Services -- 0.1% 2,000,000 0.00 LIBOR+ Aristocrat International Pty, Ltd., 200bps Term B-2 Loan, 9/19/24 $ 2,006,500 1,196,382 3.88 LIBOR+ KAR Auction Services, Inc., Tranche B-5 250bps Term Loan, 3/9/23 1,204,420 137,741 4.31 LIBOR+ TMS International Corp., Term B-1 300bps Loan, 8/9/24 138,170 -------------- $ 3,349,090 -------------------------------------------------------------------------------------------------------------- Security & Alarm Services -- 0.0%+ 1,281,483 5.32 LIBOR+ Garda World Security Corp., Term B 400bps Loan, 5/3/24 $ 1,294,699 -------------------------------------------------------------------------------------------------------------- Human Resource & Employment Services -- 0.0%+ 969,573 3.24 LIBOR+ On Assignment, Inc., Tranche B-3 Term 200bps Loan, 6/5/22 $ 975,633 -------------- Total Commercial Services & Supplies $ 8,665,586 -------------------------------------------------------------------------------------------------------------- TRANSPORTATION -- 0.1% Airlines -- 0.1% 490,000 3.24 LIBOR+ American Airlines, Inc., 2017 200bps Replacement Term Loan (New), 10/10/21 $ 490,511 The accompanying notes are an integral part of these financial statements. 84 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Airlines -- (continued) 2,449,004 3.24 LIBOR+ American Airlines, Inc., 2017 200bps Replacement Term Loan, 6/27/20 $ 2,453,596 294,750 3.74 LIBOR+ Delta Air Lines Inc., Term Loan (First 250bps Lien), 8/24/22 297,328 714,375 3.74 LIBOR+ Delta Air Lines, Inc., 2014 Term B-1 250bps Loan, 10/18/18 719,063 239,422 3.56 LIBOR+ United Airlines Inc., Class B Term 225bps Loan, 4/1/24 240,589 -------------- $ 4,201,087 -------------- Total Transportation $ 4,201,087 -------------------------------------------------------------------------------------------------------------- AUTOMOBILES & COMPONENTS -- 0.2% Auto Parts & Equipment -- 0.1% 428,653 3.24 LIBOR+ Allison Transmission, Inc., Term B-3 200bps Loan, 8/23/19 $ 430,919 1,140,563 3.49 LIBOR+ American Axle & Manufacturing, Inc., 225bps Tranche B Term Loan, 3/9/24 1,140,444 957,650 5.74 LIBOR+ BBB Industries US, Initial Term Loan, 450bps 10/15/21 969,620 750,000 0.00 LIBOR+ Superior Industries International, Inc., 450bps Closing Date Term Loan, 3/22/24 742,500 794,073 3.98 LIBOR+ TI Group Automotive Systems LLC, Initial 275bps US Term Loan, 6/25/22 796,803 1,021,626 4.00 LIBOR+ Tower Automotive Holdings USA LLC, 275bps Initial Term Loan, 3/6/24 1,026,308 291,667 3.58 LIBOR+ Visteon Corp., Tranche B Loan (First 225bps Lien), 4/8/21 293,125 -------------- $ 5,399,719 -------------------------------------------------------------------------------------------------------------- Tires & Rubber -- 0.0%+ 266,667 3.24 LIBOR+ The Goodyear Tire & Rubber Co., Term 200bps Loan (Second Lien), 3/27/19 $ 267,555 -------------------------------------------------------------------------------------------------------------- Automobile Manufacturers -- 0.1% 1,669,364 3.24 LIBOR+ Chrysler Group LLC, Tranche B Term 200bps Loan, 12/29/18 $ 1,677,085 -------------- Total Automobiles & Components $ 7,344,359 -------------------------------------------------------------------------------------------------------------- CONSUMER DURABLES & APPAREL -- 0.1% Home Furnishings -- 0.0%+ 569,331 4.80 LIBOR+ Serta Simmons Bedding LLC, Initial Term 350bps Loan (First Lien), 10/21/23 $ 553,912 -------------------------------------------------------------------------------------------------------------- Housewares & Specialties -- 0.1% 527,982 3.98 LIBOR+ Prestige Brands, Inc., Term B-4 Loan, 275bps 1/20/24 $ 531,075 990,019 4.24 LIBOR+ Reynolds Group Holdings, Inc., 300bps Incremental U.S. Term Loan, 2/5/23 995,157 -------------- $ 1,526,232 -------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 85 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Leisure Products -- 0.0%+ 750,000 6.24 LIBOR+ Bass Pro Group LLC, Initial Term Loan, 500bps 11/16/23 $ 708,750 -------------------------------------------------------------------------------------------------------------- Apparel, Accessories & Luxury Goods -- 0.0%+ 374,853 3.74 LIBOR+ Hanesbrands, Inc., New Term B Loan, 250bps 4/15/22 $ 378,272 -------------- Total Consumer Durables & Apparel $ 3,167,166 -------------------------------------------------------------------------------------------------------------- CONSUMER SERVICES -- 0.3% Casinos & Gaming -- 0.1% 748,125 3.74 LIBOR+ CityCenter Holdings LLC, Term B Loan, 250bps 4/10/24 $ 751,924 220,227 4.49 LIBOR+ Golden Nugget, Inc., 10/4/23 325bps 221,658 1,535,250 4.51 LIBOR+ Scientific Games International, Inc., 325bps Initial Term B-4 Loan, 8/14/24 1,539,808 -------------- $ 2,513,390 -------------------------------------------------------------------------------------------------------------- Hotels, Resorts & Cruise Lines -- 0.0%+ 372,188 3.74 LIBOR+ Four Seasons Holdings Inc., Term Loan, 250bps 6/27/20 $ 374,659 1,280,474 3.24 LIBOR+ Hilton Worldwide Finance LLC, Series B-2 200bps Term Loan, 10/25/23 1,287,009 273,912 3.48 LIBOR+ Sabre GLBL, Inc., 2017 B-1 Incremental 225bps Term Loan, 2/22/24 275,496 -------------- $ 1,937,164 -------------------------------------------------------------------------------------------------------------- Leisure Facilities -- 0.1% 882,000 3.48 LIBOR+ Cedar Fair LP, U.S. Term B Loan, 4/7/24 225bps $ 890,048 420,019 7.50 LIBOR+ L.A. Fitness International, LLC, Tranche B 425bps Term Loan (First Lien), 4/25/20 424,350 986,278 3.24 LIBOR+ Six Flags Theme Parks, Inc., Tranche B 200bps Term Loan, 6/30/22 991,826 -------------- $ 2,306,224 -------------------------------------------------------------------------------------------------------------- Restaurants -- 0.0%+ 1,435,536 3.23 LIBOR+ KFC Holding Co., Term B Loan, 6/2/23 200bps $ 1,443,739 -------------------------------------------------------------------------------------------------------------- Education Services -- 0.0%+ 1,916,041 3.48 LIBOR+ Bright Horizons Family Solutions Inc., 225bps Term B Loan, 11/3/23 $ 1,928,816 -------------------------------------------------------------------------------------------------------------- Specialized Consumer Services -- 0.1% 473,672 5.08 LIBOR+ Allied Universal Holdco LLC, Initial Term 375bps Loan (First Lien), 7/28/22 $ 473,721 595,500 4.73 LIBOR+ Creative Artists Agency LLC, Refinancing 350bps Term Loan, 2/9/24 600,059 The accompanying notes are an integral part of these financial statements. 86 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Specialized Consumer Services -- (continued) 521,072 3.98 LIBOR+ Prime Security Services Borrower LLC, 275bps 2016-2 Refinancing Term B-1 Loan (First Lien), 5/2/22 $ 525,754 375,937 4.53 LIBOR+ Weight Watchers International, Inc., Initial 325bps Tranche B-2 Term Loan, 4/2/20 371,943 -------------- $ 1,971,477 -------------- Total Consumer Services $ 12,100,810 -------------------------------------------------------------------------------------------------------------- MEDIA -- 0.7% Broadcasting -- 0.3% 269,448 4.74 LIBOR+ CBS Radio, Inc., Term B Loan, 10/7/23 350bps $ 271,722 654,609 3.48 LIBOR+ CSC Holdings LLC, March 2017 225bps Refinancing Term Loan, 7/17/25 651,273 213,124 4.74 LIBOR+ Entercom Radio LLC, Term B Loan, 11/1/23 350bps 213,924 994,850 3.74 LIBOR+ Gray Television, Inc., Term B-2 Loan, 2/7/24 250bps 1,002,001 496,256 3.24 LIBOR+ Nielsen Finance LLC, Class B-4 Term 200bps Loan, 10/4/23 497,750 483,627 3.56 LIBOR+ Quebecor Media, Inc., Facility B-1 225bps Tranche, 8/17/20 485,894 2,000,000 0.00 LIBOR+ Raycom TV Broadcasting LLC, Tranche B 275bps Term Loan, 8/18/24 2,010,000 2,275,634 3.49 LIBOR+ Sinclair Television Group, Inc., Tranche B 225bps Term Loan, 1/31/24 2,282,509 650,000 0.00 LIBOR+ The E.W. Scripps Co., Term Loan B, 8/16/24 225bps 653,047 87,222 4.24 LIBOR+ Tribune Media Co., Term B Loan, 12/27/20 300bps 87,549 1,087,108 4.24 LIBOR+ Tribune Media Co., Term C Loan, 1/18/24 300bps 1,091,185 644,051 3.98 LIBOR+ Univision Communications, Inc., 2017 275bps Replacement Repriced First-Lien Term Loan, 3/15/24 639,075 -------------- $ 9,885,929 -------------------------------------------------------------------------------------------------------------- Cable & Satellite -- 0.2% 1,000,000 3.49 LIBOR+ Unitymedia Hessen GmbH & Co. KG, 225bps Facility B, 9/30/25 $ 998,828 2,450,000 3.73 LIBOR+ Ziggo Secured Finance Partnership,Term 250bps Loan E Facility, 4/15/25 2,457,874 1,268,688 3.24 LIBOR+ Charter Communications Operating LLC, 200bps Term F-1 Loan, 1/3/21 1,273,621 985,000 3.49 LIBOR+ Charter Communications Operating LLC, 225bps Term I-1 Loan, 1/15/24 990,130 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 87 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Cable & Satellite -- (continued) 521,732 4.07 LIBOR+ Intelsat Jackson Holdings SA, Tranche B-2 275bps Term Loan, 6/30/19 $ 520,700 246,778 3.70 LIBOR+ MCC Iowa LLC, Tranche H Term Loan, 250bps 1/29/21 248,705 1,354,693 3.45 LIBOR+ Mediacom Illinois LLC, Tranche K Term 225bps Loan, 2/19/24 1,360,789 800,000 3.98 LIBOR+ UPC Financing Partnership, Facility AP, 275bps 4/15/25 803,786 -------------- $ 8,654,433 -------------------------------------------------------------------------------------------------------------- Movies & Entertainment -- 0.2% 497,500 3.48 LIBOR+ AMC Entertainment Holdings, Inc., 2016 225bps Incremental Term Loan, 12/15/23 $ 496,318 1,421,195 3.48 LIBOR+ AMC Entertainment, Inc., Initial Term 225bps Loan, 4/30/20 1,420,769 415,094 3.83 LIBOR+ Kasima LLC, Term Loan, 5/17/21 250bps 418,381 1,252,382 3.50 LIBOR+ Live Nation Entertainment, Inc., Term B-3 225bps Loan, 10/27/23 1,258,487 397,000 4.83 LIBOR+ NVA Holdings, Inc., Term B-2 Loan (First 350bps Lien), 8/14/21 400,660 992,683 3.74 LIBOR+ Rovi Solutions Corp., Term B Loan, 7/2/21 250bps 997,204 574,500 4.08 LIBOR+ Seminole Hard Rock Entertainment, Inc., 275bps Term Loan, 5/14/20 576,894 821,620 3.74 LIBOR+ WMG Acquisition Corp., Tranche D Term 250bps Loan, 11/1/23 824,701 -------------- $ 6,393,414 -------------------------------------------------------------------------------------------------------------- Publishing -- 0.0%+ 472,955 3.73 LIBOR+ MTL Publishing LLC, Term B-5 Loan, 250bps 8/20/23 $ 474,819 671,326 4.51 LIBOR+ Quincy Media, Inc., Term Loan B, 10/19/22 325bps 674,683 -------------- $ 1,149,502 -------------- Total Media $ 26,083,278 -------------------------------------------------------------------------------------------------------------- RETAILING -- 0.2% Home Improvement Retail -- 0.0%+ 1,180,501 4.50 LIBOR+ Apex Tool Group LLC, Term Loan, 2/1/20 325bps $ 1,149,021 -------------------------------------------------------------------------------------------------------------- Specialty Stores -- 0.1% 956,886 3.98 LIBOR+ Michaels Stores, Inc., 2016 New 275bps Replacement Term B-1 Loan, 1/28/23 $ 956,437 3,500,000 5.31 LIBOR+ Staples, Inc., Closing Date Term Loan, 400bps 8/15/24 3,486,882 -------------- $ 4,443,319 -------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 88 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Automotive Retail -- 0.1% 1,300,053 3.34 LIBOR+ Avis Budget Car Rental LLC, Tranche B 200bps Term Loan, 3/15/22 $ 1,295,990 198,678 3.58 LIBOR+ Cooper-Standard Automotive, Inc., 225bps Additional Term B-1 Loan, 10/28/23 199,494 1,054,104 4.98 LIBOR+ CWGS Group LLC, Term Loan, 11/3/23 375bps 1,060,824 -------------- $ 2,556,308 -------------- Total Retailing $ 8,148,648 -------------------------------------------------------------------------------------------------------------- FOOD & STAPLES RETAILING -- 0.0%+ Food Retail -- 0.0%+ 495,019 4.33 LIBOR+ Albertson's LLC, 2017-1 Term B-5 Loan, 300bps 12/21/22 $ 477,500 1,044,458 4.32 LIBOR+ Albertson's LLC, 2017-1 Term B-6 Loan, 300bps 6/22/23 1,005,664 -------------- $ 1,483,164 -------------- Total Food & Staples Retailing $ 1,483,164 -------------------------------------------------------------------------------------------------------------- FOOD, BEVERAGE & TOBACCO -- 0.2% Agricultural Products -- 0.0%+ 1,424,375 3.78 LIBOR+ Darling International, Inc., Term B USD 250bps Loan, 12/19/20 $ 1,441,717 -------------------------------------------------------------------------------------------------------------- Packaged Foods & Meats -- 0.2% 533,425 3.48 LIBOR+ B&G Foods, Inc., Tranche B-2 Term 225bps Loan, 11/2/22 $ 537,045 2,388,000 3.80 LIBOR+ JBS USA LUX SA, Initial Term Loan, 250bps 10/30/22 2,361,434 2,142,642 3.23 LIBOR+ Pinnacle Foods Finance LLC, Initial Term 200bps Loan, 1/30/24 2,150,677 2,493,750 3.49 LIBOR+ Post Holdings, Inc., Series A Incremental 225bps Term Loan, 5/17/24 2,501,700 -------------- $ 7,550,856 -------------- Total Food, Beverage & Tobacco $ 8,992,573 -------------------------------------------------------------------------------------------------------------- HOUSEHOLD & PERSONAL PRODUCTS -- 0.1% Household Products -- 0.0%+ 1,000,000 0.00 LIBOR+ Alphabet Holding Co, Inc., Initial Term 350bps Loan (First Lien), 8/15/24 $ 992,396 540,545 3.31 LIBOR+ Spectrum Brands, Inc., 2017 Refinanced 200bps USD Term Loan, 6/23/22 544,059 -------------- $ 1,536,455 -------------------------------------------------------------------------------------------------------------- Personal Products -- 0.1% 299,250 5.16 LIBOR+ Albea Beauty Holdings SA, 1st Lien Term 375bps Loan B, 4/12/24 $ 299,437 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 89 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Personal Products -- (continued) 2,019,749 4.74 LIBOR+ Revlon Consumer Products Corp., Initial 350bps Term B Loan, 7/22/23 $ 1,816,039 -------------- $ 2,115,476 -------------- Total Household & Personal Products $ 3,651,931 -------------------------------------------------------------------------------------------------------------- HEALTH CARE EQUIPMENT & SERVICES -- 0.4% Health Care Equipment -- 0.0%+ 621,875 3.58 LIBOR+ ConvaTec, Inc., Term B Loan, 10/14/23 225bps $ 625,762 -------------------------------------------------------------------------------------------------------------- Health Care Supplies -- 0.1% 1,142,138 4.58 LIBOR+ Kinetic Concepts, Inc., Dollar Term 325bps Loan, 2/1/24 $ 1,138,926 980,075 4.24 LIBOR+ Sterigenics-Nordion Holdings LLC, 300bps Incremental Term Loan, 5/15/22 981,300 -------------- $ 2,120,226 -------------------------------------------------------------------------------------------------------------- Health Care Services -- 0.1% 460,763 3.98 LIBOR+ DaVita HealthCare Partners, Inc., 275bps Tranche B Loan (First Lien), 6/19/21 $ 464,341 1,739,603 4.24 LIBOR+ Envision Healthcare Corp., Initial Term 300bps Loan, 11/17/23 1,752,831 891,969 4.04 LIBOR+ Jaguar Holding Co., II, 2017 Term Loan, 275bps 8/18/22 897,442 487,374 4.33 LIBOR+ National Mentor Holdings, Inc., Tranche B 300bps Term Loan, 1/31/21 492,323 -------------- $ 3,606,937 -------------------------------------------------------------------------------------------------------------- Health Care Facilities -- 0.1% 299,242 4.80 LIBOR+ ATI Holdings Acquisition, Inc., Initial Term 350bps Loan (First Lien), 5/6/23 $ 302,796 15,295 4.07 LIBOR+ CHS, Incremental 2019 Term G Loan, 275bps 12/31/19 15,249 28,332 4.32 LIBOR+ CHS, Incremental 2021 Term H Loan, 300bps 1/27/21 28,221 1,942,207 3.24 LIBOR+ HCA, Inc., Tranche B-9 Term Loan, 200bps 3/10/23 1,950,839 1,075,014 4.81 LIBOR+ Kindred Healthcare, Inc., Tranche B Loan 350bps (First Lien), 4/10/21 1,076,694 1,490,147 4.81 LIBOR+ Select Medical Corp., Tranche B Term 350bps Loan, 2/13/24 1,506,203 430,123 4.74 LIBOR+ Vizient, Inc., Term B-3 Loan, 2/13/23 350bps 435,634 -------------- $ 5,315,636 -------------------------------------------------------------------------------------------------------------- Managed Health Care -- 0.0%+ 740,625 7.50 LIBOR+ Prospect Medical Holdings, Inc., Term 600bps Loan, 6/20/22 $ 753,123 -------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 90 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Health Care Technology -- 0.1% 1,383,157 3.98 LIBOR+ Change Healthcare Holdings LLC, Closing 275bps Date Term Loan, 3/1/24 $ 1,387,826 2,000,000 0.00 LIBOR+ Quintiles IMS, Inc., Incremental Term B-2 200bps Dollar Loan, 1/18/25 2,012,500 -------------- $ 3,400,326 -------------- Total Health Care Equipment & Services $ 15,822,010 -------------------------------------------------------------------------------------------------------------- PHARMACEUTICALS, BIOTECHNOLOGY & LIFE SCIENCES -- 0.2% Biotechnology -- 0.0%+ 1,093,936 4.07 LIBOR+ Alkermes, Inc., 2021 Term Loan, 275bps 9/25/19 $ 1,102,140 1,000,000 3.48 LIBOR+ INC Research Holdings, Inc., Initial Term B 225bps Loan, 6/26/24 1,004,375 -------------- $ 2,106,515 -------------------------------------------------------------------------------------------------------------- Pharmaceuticals -- 0.2% 1,072,313 5.50 LIBOR+ Endo Luxembourg Finance Co., Inc., 425bps S.a. r.l., Initial Term Loan, 4/29/24 $ 1,084,376 522,375 3.45 LIBOR+ Grifols Worldwide Operations USA, Inc., 225bps Tranche B Term Loan, 1/23/25 523,948 887,365 4.08 LIBOR+ Mallinckrodt International Finance SA, 275bps 2017 Term B Loan, 9/24/24 887,365 2,290,325 3.33 LIBOR+ RPI Finance Trust, Initial Term Loan B-6, 200bps 3/17/23 2,300,027 1,184,951 5.99 LIBOR+ Valeant Pharmaceuticals International, 475bps Inc., Series F Tranche B Term Loan, 4/1/22 1,207,317 -------------- $ 6,003,033 -------------- Total Pharmaceuticals, Biotechnology & Life Sciences $ 8,109,548 -------------------------------------------------------------------------------------------------------------- DIVERSIFIED FINANCIALS -- 0.3% Air Freight & Logistics -- 0.0%+ 192,500 5.48 LIBOR+ Syncreon Group BV, Term Loan, 9/26/20 425bps $ 169,560 -------------------------------------------------------------------------------------------------------------- Other Diversified Financial Services -- 0.1% 1,292,032 3.33 LIBOR+ Delos Finance S.a. r.l., New Loan, 200bps 10/6/23 $ 1,301,607 1,861,379 3.56 LIBOR+ Fly Funding II Sarl, Loan, 8/9/19 225bps 1,867,583 478,750 5.58 LIBOR+ Livingston International, Inc., Initial 425bps Term B-1 Loan (First Lien), 4/18/19 454,812 -------------- $ 3,624,002 -------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 91 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Specialized Finance -- 0.1% 1,453,095 3.52 LIBOR+ Restaurant Brands, 1st Lien, Term 200bps Loan B, 2/17/24 17Feb24 $ 1,453,246 900,000 3.24 LIBOR+ FleetCor Technologies Operating Co., LLC, 200bps Term B-3 Loan, 7/27/24 904,875 827,311 3.49 LIBOR+ SBA Senior Finance II LLC, Incremental 225bps Tranche B-1 Term Loan, 3/31/21 830,816 -------------- $ 3,188,937 -------------------------------------------------------------------------------------------------------------- Asset Management & Custody Banks -- 0.0%+ 425,000 2.75 LIBOR+ Fortress Investment Group LLC, Initial Term 275bps Loan, 6/12/22 $ 429,622 -------------------------------------------------------------------------------------------------------------- Diversified Capital Markets -- 0.1% 997,500 3.99 LIBOR+ Avolon TLB Borrower 1 US LLC, Initial 275bps Term B-2 Loan, 1/20/22 $ 1,000,617 1,594,274 3.49 LIBOR+ Outfront Media Capital LLC, Term Loan, 225bps 3/10/24 1,605,804 -------------- $ 2,606,421 -------------- Total Diversified Financials $ 10,018,542 -------------------------------------------------------------------------------------------------------------- INSURANCE -- 0.1% Life & Health Insurance -- 0.0%+ 737,089 7.06 LIBOR+ Integro, Ltd., Initial Term Loan (First 575bps Lien), 10/9/22 $ 735,246 -------------------------------------------------------------------------------------------------------------- Multi-line Insurance -- 0.0%+ 70,857 4.56 LIBOR+ Alliant Holdings Intermediate LLC, Initial 325bps Term Loan, 7/28/22 $ 71,229 -------------------------------------------------------------------------------------------------------------- Property & Casualty Insurance -- 0.1% 995,000 6.27 LIBOR+ Acrisure LLC, Term B Loan (First Lien), 500bps 11/3/23 $ 1,008,059 573,496 6.74 LIBOR+ Confie Seguros Holding II Co., Term B 550bps Loan, 4/13/22 567,618 350,000 4.31 LIBOR+ USI, Inc., New York, Initial Term Loan, 300bps 4/5/24 348,943 -------------- $ 1,924,620 -------------- Total Insurance $ 2,731,095 -------------------------------------------------------------------------------------------------------------- REAL ESTATE -- 0.1% Diversified REIT -- 0.0%+ 500,000 0.00 LIBOR+ iStar, Inc. (f.k.a. iStar Financial, Inc.), 300bps Loan, 10/1/21 $ 502,812 -------------------------------------------------------------------------------------------------------------- Hotel & Resort REIT -- 0.0%+ 1,117,975 3.48 LIBOR+ MGM Growth Properties Operating 225bps Partnership LP, Term B Loan, 4/7/23 $ 1,122,567 -------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 92 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Retail REITs -- 0.1% 1,667,823 4.57 LIBOR+ DTZ US Borrower LLC, 2015-1 Additional 325bps Term Loan (First Lien), 11/4/21 $ 1,673,730 -------------------------------------------------------------------------------------------------------------- Specialized REIT -- 0.0%+ 888,551 4.24 LIBOR+ Uniti Group, Inc., Shortfall Term Loan, 300bps 10/24/22 $ 823,015 -------------------------------------------------------------------------------------------------------------- Real Estate Development -- 0.0%+ 1,000,000 0.00 LIBOR+ Hanjin International Corp. (a.k.a. Wilshire 250bps Grand Center), Term Loan B, 9/20/20 $ 1,002,500 -------------- Total Real Estate $ 5,124,624 -------------------------------------------------------------------------------------------------------------- SOFTWARE & SERVICES -- 0.3% Internet Software & Services -- 0.1% 2,289,263 4.31 LIBOR+ Rackspace Hosting, Inc., 2017 300bps Refinancing Term B Loan (First Lien), 11/3/23 $ 2,289,672 992,500 3.74 LIBOR+ Vantiv LLC (f.k.a. Fifth Third Processing 200bps Solutions LLC), Initial Term B Loan, 10/14/23 996,932 1,561,710 0.00 LIBOR+ Vantiv LLC (f.k.a. Fifth Third Processing 200bps Solutions LLC), Term Loan B, 8/7/24 1,566,347 438,290 0.00 LIBOR+ Vantiv LLC (f.k.a. Fifth Third Processing 200bps Solutions LLC), Term Loan B1, 8/7/24 439,057 -------------- $ 5,292,008 -------------------------------------------------------------------------------------------------------------- IT Consulting & Other Services -- 0.0%+ 1,126,892 3.34 LIBOR+ CDW LLC, Term Loan, 8/16/23 200bps $ 1,133,935 57,079 5.98 LIBOR+ Evergreen Skills Lux Sarl, Initial Term Loan 475bps (First Lien), 4/23/21 54,028 -------------- $ 1,187,963 -------------------------------------------------------------------------------------------------------------- Data Processing & Outsourced Services -- 0.1% 1,200,000 3.49 LIBOR+ First Data Corp., 2022D New Dollar Term 225bps Loan, 7/10/22 $ 1,202,776 493,750 3.98 LIBOR+ WEX, Inc., Term B-2 Loan, 7/1/23 275bps 498,996 -------------- $ 1,701,772 -------------------------------------------------------------------------------------------------------------- Application Software -- 0.1% 495,000 6.56 LIBOR+ DTI HoldCo, Inc., Term Loan (First 525bps Lien), 9/23/23 $ 476,231 995,000 5.74 LIBOR+ Synchronoss Technologies, Inc., Initial Term 450bps Loan, 1/19/24 952,298 307,208 3.56 LIBOR+ Verint Systems, Inc., Initial Term Loan, 225bps 6/29/24 308,360 -------------- $ 1,736,889 -------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 93 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Systems Software -- 0.0%+ 201,799 3.81 LIBOR+ MA Financeco LLC, Tranche B-2 Term 250bps Loan, 11/20/21 $ 202,072 -------------- Total Software & Services $ 10,120,704 -------------------------------------------------------------------------------------------------------------- TECHNOLOGY HARDWARE & EQUIPMENT -- 0.1% Communications Equipment -- 0.1% 1,210,646 3.74 LIBOR+ Ciena Corp., Refinancing Term Loan, 250bps 2/25/22 $ 1,216,700 1,714,000 3.24 LIBOR+ CommScope, Inc., Tranche 5 Term Loan 200bps (2015), 12/29/22 1,724,680 -------------- $ 2,941,380 -------------------------------------------------------------------------------------------------------------- Electronic Equipment Manufacturers -- 0.0%+ 620,672 3.31 LIBOR+ Zebra Technologies Corp., Tranche B Term 200bps Loan, 10/27/21 $ 622,535 -------------------------------------------------------------------------------------------------------------- Electronic Manufacturing Services -- 0.0%+ 500,000 0.00 LIBOR+ TTM Technologies, Inc., Term Loan, 250bps 9/28/24 $ 502,188 -------------- Total Technology Hardware & Equipment $ 4,066,103 -------------------------------------------------------------------------------------------------------------- SEMICONDUCTORS & SEMICONDUCTOR EQUIPMENT -- 0.1% Semiconductor Equipment -- 0.1% 1,968,692 3.49 LIBOR+ Sensata Technologies BV, Sixth Amendment 225bps Term Loan, 10/14/21 $ 1,983,866 -------------------------------------------------------------------------------------------------------------- Semiconductors -- 0.0%+ 395,918 3.49 LIBOR+ MACOM Technology Solutions Holdings, 225bps Inc., Initial Term Loan, 5/12/24 $ 395,423 52,007 3.55 LIBOR+ Microsemi Corp., Closing Date Term B 225bps Loan, 12/17/22 52,178 572,497 3.48 LIBOR+ ON Semiconductor Corp., 2017 New 225bps Replacement Term Loan, 3/31/23 575,211 -------------- $ 1,022,812 -------------- Total Semiconductors & Semiconductor Equipment $ 3,006,678 -------------------------------------------------------------------------------------------------------------- TELECOMMUNICATION SERVICES -- 0.3% Integrated Telecommunication Services -- 0.2% 731,019 0.00 LIBOR+ Cincinnati Bell, Inc., Term Loan, 8/16/24 375bps $ 735,131 3,000,000 2.75 LIBOR+ CenturyLink Escrow LLC, Initial Term B 275bps Loan, 1/31/25 2,912,679 731,019 4.24 LIBOR+ Cincinnati Bell, Inc., Tranche B Term 300bps Loan, 9/10/20 735,130 643,021 0.00 LIBOR+ GCI Holdings, Inc., Term Loan B, 2/2/22 225bps 645,232 The accompanying notes are an integral part of these financial statements. 94 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Integrated Telecommunication Services -- (continued) 1,000,000 3.49 LIBOR+ Level 3 Financing, Inc., Tranche B 2024 225bps Term Loan, 2/17/24 $ 1,000,893 689,251 4.49 LIBOR+ Windstream Services LLC, Tranche B-7 325bps Term Loan, 2/8/24 591,033 -------------- $ 6,620,098 -------------------------------------------------------------------------------------------------------------- Wireless Telecommunication Services -- 0.1% 1,092,427 3.48 LIBOR+ Altice US Finance I Corp., March 2017 225bps Refinancing Term Loan, 7/28/25 $ 1,093,281 1,990,000 3.75 LIBOR+ Sprint Communications, Inc., Initial Term 250bps Loan, 2/2/24 1,995,508 1,484,673 3.98 LIBOR+ Virgin Media Bristol LLC, I Facility, 275bps 1/31/25 1,491,981 -------------- $ 4,580,770 -------------- Total Telecommunication Services $ 11,200,868 -------------------------------------------------------------------------------------------------------------- UTILITIES -- 0.2% Electric Utilities -- 0.1% 1,890,166 5.48 LIBOR+ APLP Holdings LP, Term Loan, 4/12/23 425bps $ 1,909,856 1,149,000 3.49 LIBOR+ Calpine Construction Finance Co., LP, 225bps Term B-1 Loan, 5/3/20 1,150,436 496,250 4.49 LIBOR+ The Dayton Power & Light Co., Loan, 325bps 8/18/22 503,849 -------------- $ 3,564,141 -------------------------------------------------------------------------------------------------------------- Independent Power Producers & Energy Traders -- 0.1% 540,375 4.09 LIBOR+ Calpine Corp., Term Loan (2015), 275bps 1/15/23 $ 540,206 283,475 4.09 LIBOR+ 275bps Calpine Corp., Term Loan, 1/15/24 283,280 181,514 4.49 LIBOR+ Dynegy, Inc., Tranche C-1 Term Loan, 325bps 6/27/23 182,635 1,631,092 3.58 LIBOR+ NRG Energy, Inc., Term Loan, 6/30/23 225bps 1,634,273 488,769 5.24 LIBOR+ Talen Energy Supply LLC, Term B-1 Loan, 400bps 7/6/23 479,808 895,736 5.58 LIBOR+ TerraForm AP Acquisition Holdings LLC, 425bps Term Loan, 6/26/22 915,890 -------------- $ 4,036,092 -------------- Total Utilities $ 7,600,233 -------------------------------------------------------------------------------------------------------------- Real Estate -- 0.1% TOTAL SENIOR FLOATING RATE LOAN INTERESTS (Cost $186,049,523) $ 186,674,963 -------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 95 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- TEMPORARY CASH INVESTMENTS -- 4.6% Repurchase Agreements -- 1.0% 9,620,000 $9,620,000 ScotiaBank, 1.05%, dated 9/29/17 plus accrued interest on 10/2/17 collateralized by the following: $61,755 Federal National Mortgage Association, 4.0-4.5%, 8/1/44-9/1/47 $9,751,504 Government National Mortgage Association, 3.0-4.0%, 7/20/42-6/20/47 $ 9,620,000 9,620,000 $15,085,000 RBC Capital Markets LLC, 1.04%, dated 9/29/17 plus accrued interest on 10/2/17 collateralized by the following: $601,379 Freddie Mac Giant, 3.5-4.0%, 8/1/45-1/1/47 $1,231,287 Federal National Mortgage Association, 4.0%, 10/1/33-5/1/47 $7,979,734 Government National Mortgage Association, 3.0-3.5%, 4/20/47-9/20/47 9,620,000 9,620,000 $9,620,000 TD Securities USA LLC, 1.04%, dated 9/29/17 plus accrued interest on 10/2/17 collateralized by $9,813,383 Freddie Mac, 1.5%, 1/17/20 9,620,000 9,620,000 $9,620,000 TD Securities USA LLC, 1.05%, dated 9/29/17 plus accrued interest on 10/2/17 collateralized by the following: $8,481,295 Freddie Mac, 1.5%, 1/17/20 $1,331,356 Federal National Mortgage Association, 1.5%, 7/30/20 9,620,000 -------------- $ 38,480,000 -------------------------------------------------------------------------------------------------------------- Commercial Paper -- 2.4% 800,000 Agrium, Inc., Commercial Paper, 10/3/17 (c) $ 799,880 4,005,000 Agrium Inc., Commercial Paper, 11/13/17 (c) 3,997,991 4,570,000 Agrium, Inc., Commercial Paper, 11/3/17 (c) 4,566,311 5,061,000 Amphenol Corp., Commercial Paper, 10/2/17 (c) 5,060,431 3,800,000 Amphenol Corp., Commercial Paper, 10/23/17 (c) 3,796,489 9,620,000 Mondelez International, Inc., Commercial Paper, 10/2/17 (c) 9,618,918 3,800,000 Autozone Inc., Commercial Paper, 10/4/17 (c) 3,799,285 The accompanying notes are an integral part of these financial statements. 96 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Commercial Paper -- (continued) 3,795,000 Autozone, Inc., Commercial Paper, 10/23/17 (c) $ 3,791,493 3,765,000 Bell Canada, Commercial Paper, 11/2/17 (c) 3,759,833 5,695,000 Bell Canada, Commercial Paper, 10/12/17 (c) 5,692,043 500,000 Bell Canada, Commercial Paper, 10/25/17 (c) 499,477 9,620,000 Federation, Commercial Paper, 10/2/17 (c) 9,619,066 3,745,000 Rockwell Collins, Commercial Paper, 10/12/17 (c) 3,743,141 700,000 Dominion Resources Commercial Paper, 10/13/17 (c) 699,625 990,000 Dominion Resources, Commercial Paper, 10/24/17 (c) 989,046 3,845,000 Electricite De France, Commercial Paper, 10/25/17 (c) 3,841,148 6,400,000 Southern California Edison, Commercial Paper, 10/2/17 (c) 6,399,240 3,625,000 Mitsubishi Ufj, Commercial Paper, 11/16/17 (c) 3,618,968 4,805,000 Oneok, Inc., Commercial Paper, 10/2/17 (c) 4,804,349 4,495,000 Oneok, Inc., Commercial Paper, 10/17/17 (c) 4,491,310 9,620,000 Prudential Funding LLC, Commercial Paper, 10/2/17 (c) 9,619,082 -------------- $ 93,207,126 -------------------------------------------------------------------------------------------------------------- Certificate of Deposit -- 1.2% 3,060,000 1.78 3M LIBOR+ Bank of Montreal, Floating Rate Note, 55bps 12/11/17 $ 3,063,755 3,085,000 Natixis NY, 1.4%, 10/17/17 3,085,334 4,720,000 UBS AG Stamford Branch, 1.42%, 11/2/17 4,720,666 7,455,000 UBS AG Stamford Branch, 1.42%, 11/13/17 7,456,337 2,600,000 1.95 3M LIBOR+ Bank of Montreal, Floating Rate Note, 70bps 3/16/18 2,599,693 1,800,000 1.60 3M LIBOR+ Bank of Nova Scotia Houston, Floating 30bps Rate Note, 4/12/19 1,799,458 3,500,000 1.68 3M LIBOR+ Bank of Nova Scotia Houston, Floating 38bps Rate Note, 7/18/18 3,508,134 1,250,000 BNP Paribas SA New York NY, 1.5%, 10/5/17 1,250,071 2,897,000 1.53 Cooperatieve Rabobank UA New York, Floating Rate Note, 3/6/18 2,899,378 The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 97 Schedule of Investments | 9/30/17 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Effective Reference Principal Interest Index + Amount ($) Rate (a) Spread (b) Value -------------------------------------------------------------------------------------------------------------- Certificate of Deposit -- (continued) 1,492,000 2.62 3M LIBOR+ Credit Suisse AG New York NY, Floating 130bps Rate Note, 3/8/18 $ 1,493,726 3,415,000 1.66 3M LIBOR+ Mizuho Bank, Ltd. New York, Floating 50bps Rate Note, 9/24/18 3,414,332 1,500,000 1.70 3M LIBOR+ Nordea Bank AB New York NY, Floating 38bps Rate Note, 2/21/19 1,499,586 5,895,000 Kbc Bank NV, 1.3%, 10/24/17 5,895,410 3,210,000 1.23 1M LIBOR+ Toronto-Dominion Bank New York, 26bps Floating Rate Note, 5/9/18 3,212,600 -------------- $ 45,898,480 -------------------------------------------------------------------------------------------------------------- TOTAL TEMPORARY CASH INVESTMENTS (Cost $177,613,832) $ 177,585,606 -------------------------------------------------------------------------------------------------------------- TOTAL INVESTMENT IN UNAFFILIATED ISSUERS -- 99.3% (Cost $3,858,327,796) $3,861,385,301 -------------------------------------------------------------------------------------------------------------- OTHER ASSETS & LIABILITIES -- 0.6% $ 26,321,536 -------------------------------------------------------------------------------------------------------------- NET ASSETS -- 100.0% $3,887,706,837 ============================================================================================================== + Amount rounds to less than 0.1%. (Cat Bond) Catastrophe or event-linked bond. At September 30, 2017, the value of these securities amounted to $101,361,028 or 2.6% of net assets. See Notes to Financial Statements -- Note 1H. BPS Basis Point. COF 11 Cost of Funds for the 11th District of San Francisco. H15T1Y US Treasury Yield Curve Rate T Note Constant Maturity 1 Yr. H15T3Y US Treasury Yield Curve Rate T Note Constant Maturity 3 Yr. LIBOR London-Interbank Offer Rate. T1Y US Treasury Yield Curve Rate T Note Constant Maturity 1 Yr. T-BILL US Treasury Bill. USBMMY3M US Treasury 3 Month Bill Money Market Yield. US0012M 12 month US Dollar LIBOR. ZERO Zero Constant Index. (Step) Bond issued with an initial coupon rate which converts to a higher rate at a later date. (144A) Security is exempt from registration under Rule 144A of the Securities Act of 1933. Such securities may be resold normally to qualified institutional buyers in a transaction exempt from registration. At September 29, 2017, the value of these securities amounted to $1,642,902,923 or 42.3% of net assets. REMICS Real Estate Mortgage Investment Conduits. REIT Real Estate Investment Trust. Strips Separate trading of Registered interest and principal of securities. The accompanying notes are an integral part of these financial statements. 98 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 ** Senior floating rate loan interests in which the Fund invests generally pay interest at rates that are periodically redetermined by reference to a base lending rate plus a premium. These base lending rates are generally (i) the lending rate offered by one or more major European banks, such as LIBOR (London InterBank Offered Rate), (ii) the prime rate offered by one or more major U.S. banks, (iii) the certificate of deposit or (iv) other base lending rates used by commercial lenders. The rate shown is the coupon rate at period end. (a) Debt obligation with a variable or floating interest rate. Rate shown is rate at period end. (b) Floating rate note. Reference index and spread shown at period end. (c) Security issued with a zero coupon. Income is earned through accretion of discount. (d) Structured reinsurance investment. At September 30, 2017, the value of these securities amounted to $49,809,823 or 1.3% of net assets. See Notes to Financial Statements -- Note 1H. (e) Rate to be determined. (f) Securities that used significant unobservable inputs to determine their value. Purchases and sales of securities (excluding temporary cash investments) for the six months ended September 30, 2017 were as follows: -------------------------------------------------------------------------------------------------------------- Purchases Sales -------------------------------------------------------------------------------------------------------------- Long-Term U.S. Government $ 76,762,608 $ 38,329,939 Other Long-Term Securities 1,380,918,071 850,578,599 The Fund is permitted to engage in purchase and sale transactions ("cross trades") with certain Funds and accounts for which Amundi Pioneer Asset Management, Inc., formerly Pioneer Investment Management, Inc. (the "Adviser") serves as investment adviser, as set forth in Rule 17a-7 under the Investment Company Act of 1940, pursuant to procedures adopted by the Board of Trustees. Under these procedures, cross trades are effected at current market prices. During the six months ended September 30, 2017, the Fund engaged in purchases and sales pursuant to these procedures amounting to $20,214,944 and $1,650,100, respectively, which resulted in a net realized loss of $--. At September 30, 2017, the net unrealized appreciation on investments based on cost for federal income tax purposes of $3,863,902,654 was as follows: Aggregate gross unrealized appreciation for all investments in which there is an excess of value over tax cost $ 7,664,596 Aggregate gross unrealized depreciation for all investments in which there is an excess of tax cost over value (10,181,949) -------------- Net unrealized depreciation $ (2,517,353) ============== Various inputs are used in determining the value of the Fund's investments. These inputs are summarized in the three broad levels listed below. Level 1 - quoted prices in active markets for identical securities. Level 2 - other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risk, etc.) See Notes to Financial Statements -- Note 1A. Level 3 - significant unobservable inputs (including the Fund's own assumptions in determining fair value of investments) See Notes to Financial Statements -- Note 1A. The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 99 Schedule of Investments | 9/30/17 (unaudited) (continued) The following is a summary of the inputs used as of September 30, 2017, in valuing the Fund's investments: -------------------------------------------------------------------------------------------------------- Level 1 Level 2 Level 3 Total -------------------------------------------------------------------------------------------------------- Asset Backed Securities $ -- $1,119,491,818 $ -- $1,119,491,818 Collateralized Mortgage Obligations -- 935,394,693 -- 935,394,693 Corporate Bonds Insurance Reinsurance -- 100,163,443 51,007,408 151,170,851 All Other Corporate Bonds -- 923,067,220 -- 923,067,220 U.S. Government and Agency Obligations -- 367,525,339 -- 367,525,339 Municipal Bond -- 474,811 -- 474,811 Senior Floating Rate Loan Interests -- 186,674,963 -- 186,674,963 Repurchase Agreements -- 38,480,000 -- 38,480,000 Commercial Paper -- 93,207,126 -- 93,207,126 Certificates of Deposit -- 45,898,480 -- 45,898,480 -------------------------------------------------------------------------------------------------------- Total $ -- $3,810,377,893 $ 51,007,408 $3,861,385,301 ======================================================================================================== The following is a reconciliation of assets valued using significant unobservable inputs (Level 3): ------------------------------------------------------------------------------------------------------- Corporate Bonds ------------------------------------------------------------------------------------------------------- Balance as of 3/31/17 $ 50,894,901 Realized gain (loss)(1) 2,018 Change in unrealized appreciation (depreciation)(2) (3,578,228) Purchases 20,746,033 Sales (17,057,316) Transfers in to Level 3* -- Transfers out of Level 3* -- ------------------------------------------------------------------------------------------------------- Balance as of 9/30/17 $ 51,007,408 ======================================================================================================= 1 Realized gain (loss) on these securities is included in the net realized gain (loss) from investments in the Statement of Operations. 2 Unrealized appreciation (depreciation) on these securities is included in the change in unrealized appreciation (depreciation) on investments in the Statement of Operations. * Transfers are calculated on the beginning of period values. During the six months ended September 30, 2017, there were no transfers between Levels 1, 2 and 3. Net change in unrealized appreciation (depreciation) of investments still held as of 9/30/17 $ 319,702 --------- The accompanying notes are an integral part of these financial statements. 100 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 Statement of Assets and Liabilities | 9/30/17 (unaudited) ASSETS: Investment in securities of unaffiliated issuers, at value (cost $3,858,327,796) $ 3,861,385,301 Cash 27,728,097 Receivables -- Investment securities sold 21,835,584 Fund shares sold 55,726,971 Interest 5,877,085 Unrealized appreciation on unfunded corporate loans 2,026 Other assets 199,877 --------------------------------------------------------------------------------------------- Total assets $ 3,972,754,941 ============================================================================================= LIABILITIES: Payables -- Investment securities purchased $ 71,166,272 Fund shares repurchased 11,684,776 Distributions 1,087,818 Trustee fees 4,854 Due to affiliates 387,750 Accrued expenses 716,634 --------------------------------------------------------------------------------------------- Total liabilities $ 85,048,104 ============================================================================================= NET ASSETS: Paid-in capital $ 3,911,807,949 Distributions in excess of net investment income (2,806,953) Accumulated net realized loss on investments (24,353,690) Net unrealized appreciation on investments 3,057,505 Net unrealized appreciation on unfunded coporate loans 2,026 --------------------------------------------------------------------------------------------- Net assets $ 3,887,706,837 ============================================================================================= NET ASSET VALUE PER SHARE: (No par value, unlimited number of shares authorized) Class A (based on $961,475,797/96,362,031 shares) $ 9.98 Class C (based on $619,619,297/62,182,349 shares) $ 9.96 Class C2 (based on $10,052,527/1,008,956 shares) $ 9.96 Class K (based on $107,437,822/10,758,058 shares) $ 9.99 Class Y (based on $2,189,121,344/219,323,188 shares) $ 9.98 MAXIMUM OFFERING PRICE: Class A ($9.98 (divided by) 97.5%) $ 10.24 ============================================================================================= The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 101 Statement of Operations (unaudited) For the Six Months Ended 9/30/17 INVESTMENT INCOME: Interest from unaffiliated issuers $40,689,396 ------------------------------------------------------------------------------------------------- Total investment income $40,689,396 ================================================================================================= EXPENSES: Management fees $ 5,521,468 Transfer agent fees Class A 74,158 Class C 102,970 Class C2 1,439 Class K 94 Class Y 738,702 Distribution fees Class A 846,887 Class C 1,477,303 Class C2 24,881 Shareholder communications expense 19,956 Administrative expense 501,841 Custodian fees 125,359 Registration fees 152,830 Professional fees 67,816 Printing expense 24,126 Fees and expenses of nonaffiliated Trustees 86,545 Miscellaneous 180,865 ------------------------------------------------------------------------------------------------- Total expenses $ 9,947,240 ------------------------------------------------------------------------------------------------- Net investment income $30,742,156 ------------------------------------------------------------------------------------------------- REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS: Net realized gain (loss) on: Investments from unaffiliated issuers $ (278,311) ------------------------------------------------------------------------------------------------- Change in net unrealized appreciation (depreciation) on: Investments from unaffiliated issuers $(1,392,466) Unfunded corporate loans 2,026 $(1,390,440) ------------------------------------------------------------------------------------------------- Net realized and unrealized gain (loss) on investments $(1,668,751) ------------------------------------------------------------------------------------------------- Net increase in net assets resulting from operations $29,073,405 ================================================================================================= The accompanying notes are an integral part of these financial statements. 102 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 Statements of Changes in Net Assets --------------------------------------------------------------------------------------------------- Six Months Ended 9/30/17 Year Ended (unaudited) 3/31/17 --------------------------------------------------------------------------------------------------- FROM OPERATIONS: Net investment income (loss) $ 30,742,156 $ 44,136,405 Net realized gain (loss) on investments (278,311) (1,764,194) Change in net unrealized appreciation (depreciation) on investments (1,390,440) 20,985,712 --------------------------------------------------------------------------------------------------- Net increase in net assets resulting from operations $ 29,073,405 $ 63,357,923 --------------------------------------------------------------------------------------------------- DISTRIBUTIONS TO SHAREOWNERS: Net investment income: Class A ($0.09 and $0.17 per share, respectively) $ (7,480,968) $ (11,645,585) Class C ($0.07 and $0.14 per share, respectively) (4,258,401) (7,377,025) Class C2 ($0.07 and $0.14 per share, respectively) (71,478) (133,252) Class K ($0.10 and $0.19 per share, respectively) (996,208) (314,128) Class Y ($0.09 and $0.18 per share, respectively) (18,739,078) (28,545,808) --------------------------------------------------------------------------------------------------- Total distributions to shareowners $ (31,546,133) $ (48,015,798) --------------------------------------------------------------------------------------------------- FROM FUND SHARE TRANSACTIONS: Net proceeds from sale of shares $ 1,871,514,899 $ 2,635,780,672 Reinvestment of distributions 27,201,071 42,037,618 Cost of shares repurchased (1,206,833,923) (2,126,031,078) --------------------------------------------------------------------------------------------------- Net increase in net assets resulting from Fund share transactions $ 691,882,047 $ 551,787,212 --------------------------------------------------------------------------------------------------- Net increase in net assets $ 689,409,319 $ 567,129,337 NET ASSETS: Beginning of period $ 3,198,297,518 $ 2,631,168,181 --------------------------------------------------------------------------------------------------- End of period $ 3,887,706,837 $ 3,198,297,518 --------------------------------------------------------------------------------------------------- Distributions in excess of net investment income $ (2,806,953) $ (2,002,976) =================================================================================================== The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 103 Statements of Changes in Net Assets (continued) --------------------------------------------------------------------------------------------------------- Six Months Six Months Ended Ended 9/30/17 9/30/17 Year Ended Year Ended Shares Amount 3/31/17 3/31/17 (unaudited) (unaudited) Shares Amount --------------------------------------------------------------------------------------------------------- Class A Shares sold 52,174,985 $ 520,275,082 54,032,493 $ 539,264,584 Reinvestment of distributions 667,057 6,663,954 1,052,187 10,498,392 Less shares repurchased (32,537,576) (325,004,596) (46,879,123) (467,598,705) --------------------------------------------------------------------------------------------------------- Net increase 20,304,466 $ 201,934,440 8,205,557 $ 82,164,271 ========================================================================================================= Class C Shares sold 22,303,213 $ 222,524,457 28,880,632 $ 287,826,009 Reinvestment of distributions 418,528 4,175,448 731,519 7,288,620 Less shares repurchased (17,583,084) (175,392,791) (25,444,875) (253,536,832) --------------------------------------------------------------------------------------------------------- Net increase 5,138,657 $ 51,307,114 4,167,276 $ 41,577,797 ========================================================================================================= Class C2 Shares sold 165,707 $ 1,653,551 296,871 $ 2,958,188 Reinvestment of distributions 3,625 36,158 6,343 63,187 Less shares repurchased (146,778) (1,464,026) (355,622) (3,541,422) --------------------------------------------------------------------------------------------------------- Net increase (decrease) 22,554 $ 225,683 (52,408) $ (520,047) ========================================================================================================= Class K Shares sold 2,241,232 $ 22,408,972 9,699,288 $ 96,908,050 Reinvestment of distributions 97,214 972,139 31,438 314,013 Less shares repurchased (752,602) (7,524,823) (1,064,634) (10,642,480) --------------------------------------------------------------------------------------------------------- Net increase 1,585,844 $ 15,856,288 8,666,092 $ 86,579,583 ========================================================================================================= Class Y Shares sold 110,521,405 $1,104,652,837 171,158,865 $ 1,708,823,841 Reinvestment of distributions 1,536,420 15,353,372 2,391,859 23,873,406 Less shares repurchased (69,796,637) (697,447,687) (139,378,771) (1,390,711,639) --------------------------------------------------------------------------------------------------------- Net increase 42,261,188 $ 422,558,522 34,171,953 $ 341,985,608 ========================================================================================================= The accompanying notes are an integral part of these financial statements. 104 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 Financial Highlights ------------------------------------------------------------------------------------------------------------------------------------ Six Months Ended Year Year Year Year Year 9/30/17 Ended Ended Ended Ended Ended (unaudited) 3/31/17 3/31/16 3/31/15 3/31/14 3/31/13 ------------------------------------------------------------------------------------------------------------------------------------ Class A Net asset value, beginning of period $ 9.99 $ 9.92 $ 10.00 $ 10.07 $ 10.08 $ 10.02 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ 0.09(a) $ 0.16(a) $ 0.10(a) $ 0.10 $ 0.10 $ 0.13 Net realized and unrealized gain (loss) on investments (0.01) 0.08 (0.06) (0.05) (0.01) 0.08 ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $ 0.08 $ 0.24 $ 0.04 $ 0.05 $ 0.09 $ 0.21 ------------------------------------------------------------------------------------------------------------------------------------ Distribution to shareowners: Net investment income $ (0.09) $ (0.17) $ (0.12) $ (0.12) $ (0.10) $ (0.15) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ (0.01) $ 0.07 $ (0.08) $ (0.07) $ (0.01) $ 0.06 ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 9.98 $ 9.99 $ 9.92 $ 10.00 $ 10.07 $ 10.08 ==================================================================================================================================== Total return* 0.78% 2.43% 0.41% 0.54% 0.92% 2.14% Ratio of net expenses to average net assets 0.60%** 0.61% 0.63% 0.63% 0.66% 0.72% Ratio of net investment income (loss) to average net assets 1.72%** 1.59% 1.01% 0.95% 0.93% 0.94% Portfolio turnover rate 53%** 69% 58% 45% 47% 101% Net assets, end of period (in thousands) $961,476 $759,455 $673,352 $694,221 $570,468 $381,267 ==================================================================================================================================== * Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions, the complete redemption of the investment at net asset value at the end of each period and no sales charges. Total return would be reduced if sales charges were taken into account. ** Annualized. (a) The per share data presented above is based on the average shares outstanding for the period presented. The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 105 Financial Highlights (continued) ------------------------------------------------------------------------------------------------------------------------------------ Six Months Ended Year Year Year Year Year 9/30/17 Ended Ended Ended Ended Ended (unaudited) 3/31/17 3/31/16 3/31/15 3/31/14 3/31/13 ------------------------------------------------------------------------------------------------------------------------------------ Class C Net asset value, beginning of period $ 9.97 $ 9.91 $ 9.99 $ 10.05 $ 10.07 $ 10.02 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ 0.07(a) $ 0.13(a) $ 0.07(a) $ 0.07 $ 0.08 $ 0.09 Net realized and unrealized gain (loss) on investments (0.01) 0.07 (0.06) (0.04) (0.03) 0.07 ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $ 0.06 $ 0.20 $ 0.01 $ 0.03 $ 0.05 $ 0.16 ------------------------------------------------------------------------------------------------------------------------------------ Distribution to shareowners: Net investment income $ (0.07) $ (0.14) $ (0.09) $ (0.09) $ (0.07) $ (0.11) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ (0.01) $ 0.06 $ (0.08) $ (0.06) $ (0.02) $ 0.05 ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 9.96 $ 9.97 $ 9.91 $ 9.99 $ 10.05 $ 10.07 ==================================================================================================================================== Total return* 0.62% 2.00% 0.11% 0.34% 0.54% 1.61% Ratio of net expenses to average net assets 0.92%** 0.93% 0.94% 0.94% 0.97% 1.03% Ratio of net investment income (loss) to average net assets 1.40%** 1.27% 0.70% 0.66% 0.62% 0.63% Portfolio turnover rate 53%** 69% 58% 45% 47% 101% Net assets, end of period (in thousands) $619,619 $568,840 $524,030 $594,283 $575,457 $330,828 ==================================================================================================================================== * Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions, the complete redemption of the investment at net asset value at the end of each period and no sales charges. Total return would be reduced if sales charges were taken into account. ** Annualized. (a) The per share data presented above is based on the average shares outstanding for the period presented. The accompanying notes are an integral part of these financial statements. 106 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 ---------------------------------------------------------------------------------------------------------------------------- Six Months Ended Year Year Year 9/30/17 Ended Ended Ended 8/31/13 (unaudited) 3/31/17 3/31/16 3/31/15 to 3/31/14 ---------------------------------------------------------------------------------------------------------------------------- Class C2 Net asset value, beginning of period $ 9.97 $ 9.91 $ 9.99 $ 10.05 $10.04 ---------------------------------------------------------------------------------------------------------------------------- Increase (decrease) from investment operations: Net investment income (loss) $ 0.07(b) $ 0.13(b) $ 0.07(b) $ 0.06 $ 0.07 Net realized and unrealized gain (loss) on investments (0.01) 0.07 (0.06) (0.03) (0.01) ---------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) from investment operations $ 0.06 $ 0.20 $ 0.01 $ 0.03 $ 0.06 ---------------------------------------------------------------------------------------------------------------------------- Distribution to shareowners: Net investment income $ (0.07) $(0.14) $ (0.09) $ (0.09) $(0.05) ---------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) in net asset value $ (0.01) $ 0.06 $ (0.08) $ (0.06) $ 0.01 ---------------------------------------------------------------------------------------------------------------------------- Net asset value, end of period $ 9.96 $ 9.97 $ 9.91 $ 9.99 $10.05 ============================================================================================================================ Total return* 0.62% 2.00% 0.11% 0.33% 0.56%(a) Ratio of net expenses to average net assets 0.91%** 0.93% 0.94% 0.95% 0.99%** Ratio of net investment income (loss) to average net assets 1.41%** 1.27% 0.69% 0.66% 0.68%** Portfolio turnover rate 53%** 69% 58% 45% 47% Net assets, end of period (in thousands) $10,053 $9,834 $10,292 $11,258 $3,699 ============================================================================================================================ * Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions, the complete redemption of the investment at net asset value at the end of each period and no sales charges. Total return would be reduced if sales charges were taken into account. ** Annualized. (a) Not Annualized. (b) The per share data presented above is based on the average shares outstanding for the period presented. The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 107 Financial Highlights (continued) ------------------------------------------------------------------------------------------------------------------------------------ Six Months Ended Year Year Year Year 9/30/17 Ended Ended Ended Ended 12/20/12 (unaudited) 3/31/17 3/31/16 3/31/15 3/31/14 to 3/31/13 ------------------------------------------------------------------------------------------------------------------------------------ Class K Net asset value, beginning of period $ 9.99 $ 9.93 $10.01 $10.07 $10.08 $10.09 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ 0.10(c) $ 0.19(c) $ 0.12(c) $ 0.14 $ 0.12 $ 0.03 Net realized and unrealized gain (loss) on investments 0.00(a) 0.06 (0.06) (0.06) (0.00)(a) 0.01 ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $ 0.10 $ 0.25 $ 0.06 $ 0.08 $ 0.12 $ 0.04 ------------------------------------------------------------------------------------------------------------------------------------ Distribution to shareowners: Net investment income $ (0.10) $ (0.19) $(0.14) $(0.14) $(0.13) $(0.05) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ -- $ 0.06 $(0.08) $(0.06) $(0.01) $(0.01) ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 9.99 $ 9.99 $ 9.93 $10.01 $10.07 $10.08 ==================================================================================================================================== Total return* 0.99% 2.55% 0.64% 0.83% 1.16% 0.43%(b) Ratio of net expenses to average net assets 0.38%** 0.42% 0.42% 0.41% 0.41% 0.53%** Ratio of net investment income (loss) to average net assets 1.95%** 1.92% 1.24% 1.28% 1.19% 1.25%** Portfolio turnover rate 53%** 69% 58% 45% 47% 101% Net assets, end of period (in thousands) $107,438 $91,666 $5,026 $5,091 $ 10 $ 10 ==================================================================================================================================== * Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions, the complete redemption of the investment at net asset value at the end of each period. ** Annualized. (a) Amount rounds to less than $0.01 or $(0.01) per share. (b) Not Annualized. (c) The per share data presented above is based on the average shares outstanding for the period presented. The accompanying notes are an integral part of these financial statements. 108 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 ----------------------------------------------------------------------------------------------------------------------------------- Six Months Ended Year Year Year Year Year 9/30/17 Ended Ended Ended Ended Ended (unaudited) 3/31/17 3/31/16 3/31/15 3/31/14 3/31/13 ----------------------------------------------------------------------------------------------------------------------------------- Class Y Net asset value, beginning of period $ 9.99 $ 9.93 $ 10.01 $ 10.07 $ 10.09 $ 10.03 ----------------------------------------------------------------------------------------------------------------------------------- Increase (decrease) from investment operations: Net investment income (loss) $ 0.09(a) $ 0.17(a) $ 0.11(a) $ 0.11 $ 0.12 $ 0.14 Net realized and unrealized gain (loss) on investments (0.01) 0.07 (0.06) (0.03) (0.02) 0.09 ----------------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) from investment operations $ 0.08 $ 0.24 $ 0.05 $ 0.08 $ 0.10 $ 0.23 ----------------------------------------------------------------------------------------------------------------------------------- Distribution to shareowners: Net investment income $ (0.09) $ (0.18) $ (0.13) $ (0.14) $ (0.12) $ (0.17) ----------------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) in net asset value $ (0.01) $ 0.06 $ (0.08) $ (0.06) $ (0.02) $ 0.06 ----------------------------------------------------------------------------------------------------------------------------------- Net asset value, end of period $ 9.98 $ 9.99 $ 9.93 $ 10.01 $ 10.07 $ 10.09 =================================================================================================================================== Total return* 0.85% 2.46% 0.54% 0.79% 0.99% 2.35% Ratio of net expenses to average net assets 0.46%** 0.50% 0.51% 0.51% 0.54% 0.55% Ratio of net investment income (loss) to average net assets 1.86%** 1.70% 1.15% 1.08% 1.05% 1.11% Portfolio turnover rate 53%** 69% 58% 45% 47% 101% Net assets, end of period (in thousands) $2,189,121 $1,768,502 $1,418,468 $1,188,107 $912,810 $608,818 =================================================================================================================================== * Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions, the complete redemption of the investment at net asset value at the end of each period. ** Annualized. (a) The per share data presented above is based on the average shares outstanding for the period presented. The accompanying notes are an integral part of these financial statements. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 109 Notes to Financial Statements | 9/30/17 (unaudited) 1. Organization and Significant Accounting Policies Pioneer Multi-Asset Ultrashort Income Fund (the Fund) is one of three portfolios comprising Pioneer Series Trust X, a Delaware statutory trust. The Fund is registered under the Investment Company Act of 1940 as a diversified, open-end management investment company. The investment objective of the Fund is to seek a high level of current income to the extent consistent with a relatively high level of stability of principal. The Fund offers five classes of shares designated as Class A, Class C, Class C2, Class K and Class Y shares. Each class of shares represents an interest in the same portfolio of investments of the Fund and has identical rights (based on relative net asset values) to assets and liquidation proceeds. Share classes can bear different rates of class-specific fees and expenses, such as transfer agent and distribution fees. Differences in class-specific fees and expenses will result in differences in net investment income and, therefore, the payment of different dividends from net investment income earned by each class. The Amended and Restated Declaration of Trust of the Fund gives the Board of Trustees the flexibility to specify either per-share voting or dollar-weighted voting when submitting matters for shareholder approval. Under per-share voting, each share of a class of the Fund is entitled to one vote. Under dollar-weighted voting, a shareholder's voting power is determined not by the number of shares owned, but by the dollar value of the shares on the record date. Each share class has exclusive voting rights with respect to matters affecting only that class, including with respect to the distribution plan for that class. There is no distribution plan for Class K or Class Y shares. On July 3, 2017, Amundi acquired Pioneer Investments, a group of asset management companies located throughout the world. Amundi, one of the world's largest asset managers, is headquartered in Paris, France. As a result of the transaction, Pioneer Investment Management, Inc., the Funds' investment adviser, became an indirect wholly owned subsidiary of Amundi and Amundi's wholly owned subsidiary, Amundi USA, Inc. Prior to July 3, 2017, Pioneer Investments was owned by Pioneer Global Asset Management S.p.A., a wholly owned subsidiary of UniCredit S.p.A. In connection with the transaction, the names of the Funds' investment adviser and principal underwriter changed. Effective July 3, 2017, the name of Pioneer Investment Management, Inc. changed to Amundi Pioneer Asset Management, Inc. (the Adviser) and the name of Pioneer Funds Distributor, Inc. changed to Amundi Pioneer Distributor, Inc. (the Distributor). 110 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 In October 2016, the Securities and Exchange Commission (SEC) released its Final Rule on Investment Company Reporting Modernization. In addition to introducing two new regulatory reporting forms (Form N-PORT and Form N-CEN), the Final Rule amends Regulation S-X, which impacts financial statement presentation, particularly related to the presentation of derivative investments. The Fund's financial statements were prepared in compliance with the amendments to Regulation S-X. The Fund's financial statements have been prepared in conformity with U.S. generally accepted accounting principles (U.S. GAAP) that require the management of the Fund to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of income, expenses and gains and losses on investments during the reporting period. Actual results could differ from those estimates. The Fund is an investment company and follows investment company accounting and reporting guidance under U.S. GAAP. The following is a summary of significant accounting policies followed by the Fund in the preparation of its financial statements: A. Security Valuation The net asset value of the Fund is computed once daily, on each day the New York Stock Exchange (NYSE) is open, as of the close of regular trading on the NYSE. Fixed income securities are valued by using prices supplied by independent pricing services, which consider such factors as market prices, market events, quotations from one or more brokers, Treasury spreads, yields, maturities and ratings, or may use a pricing matrix or other fair value methods or techniques to provide an estimated value of the security or instrument. A pricing matrix is a means of valuing a debt security on the basis of current market prices for other debt securities, historical trading patterns in the market for fixed income securities and/or other factors. Non-U.S. debt securities that are listed on an exchange will be valued at the bid price obtained from an independent third party pricing service. When independent third party pricing services are unable to supply prices, or when prices or market quotations are considered to be unreliable, the value of that security may be determined using quotations from one or more broker-dealers. Loan interests are valued in accordance with guidelines established by the Board of Trustees at the mean between the last available bid and asked prices from one or more brokers or dealers as obtained from Loan Pricing Corporation, an independent third party pricing service. If price information is not available from Loan Pricing Corporation, or if the price information is deemed to be unreliable, price information will be obtained from an Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 111 alternative loan interest pricing service. If no reliable price quotes are available from either the primary or alternative pricing service, broker quotes will be solicited. Event-linked bonds or catastrophe bonds are valued at the bid price obtained from an independent third party pricing service. Other insurance linked securities (including sidecars, collateralized reinsurance and industry loss warranties) may be valued at the bid price obtained from an independent pricing service, or through a third party using a pricing matrix, insurance industry valuation models, or other fair value methods or techniques to provide an estimated value of the instrument. The value of foreign securities is translated into U.S. dollars based on foreign currency exchange rate quotations supplied by a third party pricing source. Trading in non-U.S. equity securities is substantially completed each day at various times prior to the close of the NYSE. The values of such securities used in computing the net asset value of the Fund's shares are determined as of such times. The fund may use a fair value model developed by an independent pricing service to value non-U.S. equity securities. Shares of open-end registered investment companies (including money market mutual funds) are valued at such funds' net asset value. Repurchase agreements are valued at par. Cash may include overnight time deposits at approved financial institutions. Securities or loan interests for which independent pricing services or broker-dealers are unable to supply prices or for which market prices and/or quotations are not readily available or are considered to be unreliable are valued by a fair valuation team comprised of certain personnel of the Adviser pursuant to procedures adopted by the Fund's Board of Trustees. The Adviser's fair valuation team uses fair value methods approved by the Valuation Committee of the Board of Trustees. The Adviser's fair valuation team is responsible for monitoring developments that may impact fair valued securities and for discussing and assessing fair values on an ongoing basis, and at least quarterly, with the Valuation Committee of the Board of Trustees. Inputs used when applying fair value methods to value a security may include credit ratings, the financial condition of the company, current market conditions and comparable securities. The Fund may use fair value methods if it is determined that a significant event has occurred after the close of the exchange or market on which the security trades and prior to the determination of the Fund's net asset value. Examples of a significant event might include political or economic news, corporate restructurings, natural disasters, terrorist activity or trading halts. Thus, the valuation of the Fund's securities may differ significantly from exchange prices and such differences could be material. 112 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 At September 30, 2017, no securities were valued using fair value methods (other than securities valued using prices supplied by independent pricing services, broker-dealers or using a third party insurance industry pricing model). B. Investment Income and Transactions Principal amounts of mortgage-backed securities are adjusted for monthly paydowns. Premiums and discounts related to certain mortgage-backed securities are amortized or accreted in proportion to the monthly paydowns. All discounts/premiums on purchase prices of debt securities are accreted/amortized for financial reporting purposes over the life of the respective securities, and such accretion/amortization is included in interest income. Interest income, including interest on income bearing cash accounts, is recorded on the accrual basis, net of unrecoverable foreign taxes withheld at the applicable country rates and net of income accrued or defaulted securities. Interest and dividend income payable by delivery of additional shares is reclassified as PIK (payment-in-kind) income upon receipt and is included in interest and dividend income, respectively. Security transactions are recorded as of trade date. Gains and losses on sales of investments are calculated on the identified cost method for both financial reporting and federal income tax purposes. C. Foreign Currency Translation The books and records of the Fund are maintained in U.S. dollars. Amounts denominated in foreign currencies are translated into U.S. dollars using current exchange rates. Net realized gains and losses on foreign currency transactions, if any, represent, among other things, the net realized gains and losses on foreign currency contracts, disposition of foreign currencies and the difference between the amount of income accrued and the U.S. dollars actually received. Further, the effects of changes in foreign currency exchange rates on investments are not segregated in the Statement of Operations from the effects of changes in the market prices of those securities but are included with the net realized and unrealized appreciation or depreciation on investments. D. Federal Income Taxes It is the Fund's policy to comply with the requirements of the Internal Revenue Code applicable to regulated investment companies and to distribute all of its net taxable income and net realized capital gains, if any, to its shareowners. Therefore, no provision for federal income taxes is required. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 113 As of March 31, 2017, the Fund had not accrued any interest or penalties with respect to uncertain tax positions, which, if applicable, would be recorded as an income tax expense in the Statement of Operations. Tax returns filed within the prior three years are subject to examination by Federal and State tax authorities. The amount and character of income and capital gain distributions to shareowners are determined in accordance with federal income tax rules, which may differ from U.S. GAAP. Distributions in excess of net investment income or net realized gains are temporary overdistributions for financial statement purposes resulting from differences in the recognition or classification of income or distributions for financial statement and tax purposes. Capital accounts within the financial statements are adjusted for permanent book/tax differences to reflect tax character, but are not adjusted for temporary differences. The tax character of current year distributions payable will be determined at the end of the current fiscal year. The tax character of distributions paid during the year ended March 31, 2017 was as follows: --------------------------------------------------------------------------- 2017 --------------------------------------------------------------------------- Distributions paid from: Ordinary income $ 48,015,798 --------------------------------------------------------------------------- Total $ 48,015,798 =========================================================================== The following shows the components of distributable earnings on a federal income tax basis at March 31, 2017: --------------------------------------------------------------------------- 2017 --------------------------------------------------------------------------- Distributable earnings: Undistributed ordinary income $ 4,049,763 Capital loss carryforward (24,060,252) Current year dividend payable (493,008) Unrealized depreciation (1,124,887) --------------------------------------------------------------------------- Total $(21,628,384) =========================================================================== The difference between book-basis and tax-basis unrealized depreciation is attributable to the tax deferral of losses on wash sales, adjustments relating to catastrophe bonds and the tax treatment of premium and amortization. E. Fund Shares The Fund records sales and repurchases of its shares as of trade date. The Distributor earned $4,788 in underwriting commissions on the sale of Class A shares during the six months ended September 30, 2017. 114 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 F. Class Allocations Income, common expenses, and realized and unrealized appreciation and depreciation are calculated at the Fund level and allocated daily to each class of shares based on its respective percentage of adjusted net assets at the beginning of the day. Distribution fees are calculated based on the average daily net asset value attributable to Class A, Class C and Class C2 shares of the Fund, respectively (see Note 4). Class K and Class Y shares do not pay distribution fees. All expenses and fees paid to the Fund's transfer agent, for its services are allocated among the classes of shares based on the number of accounts in each class and the ratable allocation of related out-of-pocket expenses (see Note 3). The Fund declares as daily dividends substantially all of its net investment income. All dividends are paid on a monthly basis. Short-term capital gain distributions, if any, may be declared with the daily dividends. Distributions to shareowners are recorded as of the ex-dividend date. Distributions paid by the Fund with respect to each class of shares are calculated in the same manner and at the same time except that net investment income dividends to Class A, Class C, Class C2, Class K and Class Y shares can reflect different transfer agent and distribution expense rates. G. Risks The value of securities held by the Fund may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic, political or regulatory conditions, inflation, changes in interest rates, lack of liquidity in the bond markets or adverse investor sentiment. In the past several years, financial markets have experienced increased volatility, depressed valuations, decreased liquidity and heightened uncertainty. These conditions may continue, recur, worsen or spread. When interest rates rise, the prices of fixed-income securities in the Fund will generally fall. Conversely, when interest rates fall, the prices of fixed-income securities in the Fund will generally rise. Interest rates in the U.S. recently have been historically low, so the Fund faces a heightened risk that interest rates may rise. A general rise in interest rates may cause investors to move out of fixed income securities on a large scale, which could adversely affect the price and liquidity of fixed income securities and could also result in increased redemptions from the Fund. Investments in the Fund are subject to possible loss due to the financial failure of issuers of underlying securities and the issuers' inability to meet their debt obligations. Certain securities in which the Fund invests, including floating rate loans, once sold, may not settle for an extended period (for example, several weeks or even longer). The Fund will not receive its sale proceeds until that time, which may constrain the Fund's ability to meet its obligations (including obligations to redeeming Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 115 shareholders). The Fund's prospectus contains unaudited information regarding the Fund's principal risks. Please refer to that document when considering the Fund's principal risks. H. Insurance-Linked Securities (ILS) The Fund invests in event-linked bonds. Event-linked bonds are floating rate debt obligations for which the return of principal and the payment of interest are contingent on the non-occurrence of a pre-defined "trigger" event, such as a hurricane or an earthquake of a specific magnitude. The trigger event's magnitude may be based on losses to a company or industry, industry indexes or readings of scientific instruments, or may be based on specified actual losses. If a trigger event, as defined within the terms of an event-linked bond occurs, the Fund may lose a portion or all of its accrued interest and/or principal invested in such event-linked bond. The Fund is entitled to receive principal and interest payments so long as no trigger event occurs of the description and magnitude specified by the instrument. In addition to the specified trigger events, event-linked bonds may expose the Fund to other risks, including but not limited to issuer (credit) default, adverse regulatory or jurisdictional interpretations and adverse tax consequences. The Fund's investments in ILS may include special purpose vehicles ("SPVs") or similar instruments structured to comprise a portion of a reinsurer's catastrophe-oriented business, known as quota share instruments (sometimes referred to as reinsurance sidecars), or to provide reinsurance relating to specific risks to insurance or reinsurance companies through a collateralized instrument, known as collateralized reinsurance. Structured reinsurance investments also may include industry loss warranties ("ILWs"). A traditional ILW takes the form of a bilateral reinsurance contract, but there are also products that take the form of derivatives, collateralized structures, or exchange traded instruments. Structured reinsurance investments, including quota share instruments, collateralized reinsurance investments and ILWs, are generally subject to the same risks as event-linked bonds. In addition, where the instruments are based on the performance of underlying reinsurance contracts, the Fund has limited transparency into the individual underlying contracts and therefore must rely upon the risk assessment and sound underwriting practices of the issuer. Accordingly, it may be more difficult for the Adviser to fully evaluate the underlying risk profile of the Fund's structured reinsurance investments and therefore the Fund's assets are placed at greater risk of loss than if the Adviser had more complete information. Structured reinsurance instruments generally will be considered illiquid securities by the Fund. These securities may be difficult to purchase, sell or unwind. Illiquid securities also may be difficult to value. If the Fund is forced to sell an illiquid asset, the Fund may be forced to sell at a loss. 116 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 I. Repurchase Agreements Repurchase agreements are arrangements under which the Fund purchases securities from a broker-dealer or a bank, called the counterparty, upon the agreement of the counterparty to repurchase the securities from the Fund at a later date, and at a specific price, which is typically higher than the purchase price paid by the Fund. The securities purchased serve as the Fund's collateral for the obligation of the counterparty to repurchase the securities. The value of the collateral, including accrued interest, is required to be equal to or in excess of the repurchase price. The collateral for all repurchase agreements is held in safekeeping in the customer-only account of the Fund's custodian or a subcustodian of the Fund. The Adviser is responsible for determining that the value of the collateral remains at least equal to the repurchase price. In the event of a default by the counterparty, the Fund is entitled to sell the securities, but the Fund may not be able to sell them for the price at which they were purchased, thus causing a loss to the Fund. Additionally, if the counterparty becomes insolvent, there is some risk that the Fund will not have a right to the securities, or the immediate right to sell the securities. Open repurchase agreements as of September 30, 2017 are disclosed in the Fund's Schedule of Investments. 2. Management Agreement The Adviser manages the Fund's portfolio. Management fees are calculated daily at the annual rate equal to 0.35% of the Fund's average daily net assets up to $1 billion and 0.30% on assets over $1 billion. For the six months ended September 30, 2017, the effective management fee (excluding waivers and/or assumption of expenses) was equivalent to 0.32% of the Fund's average daily net assets. In addition, under the management and administration agreements, certain other services and costs, including accounting, regulatory reporting, and insurance premiums, are paid by the Fund as administrative reimbursements. Included in "Due to affiliates" reflected on the Statement of Assets and Liabilities is $278,148 in management fees, administrative costs and certain other reimbursements payable to the Adviser at September 30, 2017. 3. Transfer Agent Boston Financial Data Services, Inc. serves as the transfer agent to the Fund at negotiated rates. Transfer agent fees and payables shown on the Statement of Operations and the Statement of Assets and Liabilities, respectively, include sub-transfer agent expenses incurred through the Fund's omnibus relationship contracts. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 117 In addition, the Fund reimbursed the transfer agent for out-of-pocket expenses incurred by the transfer agent related to shareholder communications activities such as proxy and statement mailings and outgoing phone calls. For the six months ended September 30, 2017, such out-of-pocket expenses by class of shares were as follows: ---------------------------------------------------------------------------- Shareholder Communications: ---------------------------------------------------------------------------- Class A $ 2,165 Class C 10,900 Class C2 38 Class K 7 Class Y 6,846 ---------------------------------------------------------------------------- Total $19,956 ============================================================================ 4. Distribution Plan The Fund has adopted a distribution plan (the Plan) pursuant to Rule 12b-1 of the Investment Company Act of 1940 with respect to its Class A, Class C and Class C2 shares. Pursuant to the Plan, the Fund pays the Distributor 0.20% of the average daily net assets attributable to Class A shares as compensation for personal services and/or account maintenance services or distribution services with regard to Class A shares. Pursuant to the Plan, the Fund also pays the Distributor 0.50% of the average daily net assets attributable to Class C and Class C2 shares. The fee for Class C and Class C2 shares consists of a 0.25% service fee and a 0.25% distribution fee paid as compensation for personal services and/or account maintenance services or distribution services with regard to Class C and Class C2 shares. Included in "Due to affiliates" reflected on the Statement of Assets and Liabilities is $109,602 in distribution fees payable to the Distributor at September 30, 2017. In addition, redemptions of each class of shares (except Class K and Class Y shares) may be subject to a contingent deferred sales charge (CDSC). A CDSC of 1.00% may be imposed on redemptions of certain net asset value purchases of Class A shares within 12 months of purchase. For Class C2 shares redemptions of shares within 12 months of purchase are subject to a CDSC of 1.00%, based on the lower of cost or market value of shares being redeemed. Shares purchased as part of an exchange remain subject to any CDSC that applied to the original purchase of those shares. There is no CDSC for Class K and Class Y shares. Proceeds from the CDSCs are paid to the Distributor. For the six months ended September 30, 2017, CDSCs of $80,430 were paid to the Distributor. 118 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 5. Line of Credit Facility The Fund, along with certain other funds in the Pioneer Family of Funds (the Funds), participates in a committed, unsecured revolving line of credit facility. Borrowings are used solely for temporary or emergency purposes. The Fund may borrow up to the lesser of the amount available under the facility or the limits set for borrowing by the Fund's prospectus and the 1940 Act. The credit facility in which the Fund participated until February 9, 2016 was in the amount of $240 million. The credit facility in which the Fund participated until February 7, 2017 was in the amount of $220 million. Effective February 8, 2017, the Fund participates in a facility that is in the amount of $195 million. Under such facility, depending on the type of loan, interest on borrowings is payable at the London Interbank Offered Rate (LIBOR) plus 0.85% on an annualized basis, or the Alternate Base Rate, which is the greater of (a) the facility's administrative agent's daily announced prime rate on the borrowing date, (b) 2% plus the Federal Funds Rate on the borrowing date or (c) 2% plus the overnight Eurodollar rate on the borrowing date. The Funds pay an annual commitment fee to participate in a credit facility. The commitment fee is allocated among participating Funds based on an allocation schedule set forth in the credit agreement. For the six months ended September 30, 2017, the Fund had no borrowings under the credit facility. 6. Unfunded Loan Commitments The Fund may enter into unfunded loan commitments. Unfunded loan commitments may be partially or wholly unfunded. During the contractual period, the Fund is obligated to provide funding to the borrower upon demand. A fee is earned by the Fund on the unfunded commitment and is recorded as interest income in the Statement of Operations. As of September 30, 2017, the Fund had the following unfunded loan commitments outstanding: ----------------------------------------------------------------------------------------- Unrealized Loan Shares Cost Value Appreciation ----------------------------------------------------------------------------------------- Shutterfly, Inc., Delay Draw Term Loan 2,250,000 $2,238,835 $2,240,861 $2,026 ----------------------------------------------------------------------------------------- Total $2,238,835 $2,240,861 $2,026 ========================================================================================= Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 119 7. Shareholder Meeting Results At a special meeting held on June 13, 2017, shareholders of the Fund were asked to consider the proposals described below. A report of the total votes cast by the Fund's shareholders (or, with respect to Proposal 2, by shareholders of Pioneer Series Trust X, as noted below) follows: ------------------------------------------------------------------------------------------------------ For Against Abstain Broker Non-Votes ------------------------------------------------------------------------------------------------------ Proposal 1 - To approve 145,588,333.187 771,857.100 3,217,989.650 45,350,388.100 a New Management Agreement with the Adviser -------------------------------------------------------------------------------------------------- For Withhold -------------------------------------------------------------------------------------------------- Proposal 2 - To elect Trustees* -------------------------------------------------------------------------------------------------- David R. Bock 343,352,480.124 5,326,068.613 -------------------------------------------------------------------------------------------------- Benjamin M. Friedman 343,252,747.228 5,425,801.509 -------------------------------------------------------------------------------------------------- Margaret B.W. Graham 343,431,726.450 5,246,822.287 -------------------------------------------------------------------------------------------------- Lisa M. Jones 343,414,583.887 5,263,964.850 -------------------------------------------------------------------------------------------------- Lorraine H. Monchak 339,444,451.562 9,234,097.175 -------------------------------------------------------------------------------------------------- Thomas J. Perna 343,393,493.010 5,285,055.727 -------------------------------------------------------------------------------------------------- Marguerite A. Piret 343,442,072.938 5,236,475.799 -------------------------------------------------------------------------------------------------- Fred J. Ricciardi 343,367,033.730 5,311,515.007 -------------------------------------------------------------------------------------------------- Kenneth J. Taubes 343,361,588.526 5,316,960.211 -------------------------------------------------------------------------------------------------- * Proposal 2 was voted on and approved by all series of Pioneer Series Trust X. Results reported above reflect the combined votes of all series of the Trust. 120 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 ADDITIONAL INFORMATION Change in Independent Registered Public Accounting Firm Prior to July 3, 2017 Pioneer Investment Management, Inc. (the "Adviser"), the Fund's investment adviser, was an indirect, wholly owned subsidiary of UniCredit S.p.A. ("UniCredit"). On that date, UniCredit completed the sale of its Pioneer Investments business, which includes the Adviser, to Amundi (the "Transaction"). As a result of the Transaction, the Adviser became an indirect, wholly-owned subsidiary of Amundi. Amundi is controlled by Credit Agricole S.A. Amundi is headquartered in Paris, France, and, as of September 30, 2016, had more than $1.1 trillion in assets under management worldwide. Deloitte & Touche LLP ("D&T"), the Fund's previous independent registered public accounting firm, informed the Audit Committee and the Board that it would no longer be independent with respect to the Fund upon the completion of the Transaction as a result of certain services being provided to Amundi and Credit Agricole, and, accordingly, that it intended to resign as the Fund's independent registered public accounting firm upon the completion of the Transaction. D&T's resignation was effective on July 3, 2017, when the Transaction was completed. During the periods as to which D&T has served as the Fund's independent registered public accounting firm, including the Fund's two most recent fiscal years preceding the fiscal year ended March 31, 2017, D&T's reports on the Fund's financial statements have not contained an adverse opinion or disclaimer of opinion and have not been qualified or modified as to uncertainty, audit scope or accounting principles. Further, there have been no disagreements with D&T on any matter of accounting principles or practices, financial statement disclosure, or auditing scope or procedure, which, if not resolved to the satisfaction of D&T, would have caused D&T to make reference to the subject matter of the disagreement in connection with its report on the financial statements. In addition, there have been no reportable events of the kind described in Item 304(a)(1)(v) of Regulation S-K under the Securities Exchange Act of 1934. Effective immediately following the completion of the Transaction on July 3, 2017, the Board, acting upon the recommendation of the Audit Committee, engaged a new independent registered public accounting firm, Ernst & Young LLP ("EY"), for the Fund's fiscal year ended March 31, 2018. Prior to its engagement, EY had advised the Fund's Audit Committee that EY had identified the following matters, in each case relating to services rendered by other member firms of Ernst & Young Global Limited, all of which are located outside the United States, to UniCredit and certain of its subsidiaries during the period commencing July 1, 2016, that it determined to be Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 121 inconsistent with the auditor independence rules set forth by the Securities and Exchange Commission ("SEC"): (a) project management support services to UniCredit in the Czech Republic, Germany, Italy, Serbia and Slovenia in relation to twenty-two projects, that were determined to be inconsistent with Rule 2-01(c)(4)(vi) of Regulation S-X (management functions); (b) two engagements for UniCredit in Italy where fees were contingent/success based and that were determined to be inconsistent with Rule 2-01(c)(5) of Regulation S-X (contingent fees); (c) four engagements where legal and expert services were provided to UniCredit in the Czech Republic and Germany, and twenty engagements where the legal advisory services were provided to UniCredit in Austria, Czech Republic, Italy and Poland, that were determined to be inconsistent with Rule 2-01(c)(4)(ix) and (x) of Regulation S-X (legal and expert services); and (d) two engagements for UniCredit in Italy involving assistance in the sale of certain assets, that were determined to be inconsistent with Rule 2-01(c)(4)(viii) of Regulation S-X (broker-dealer, investment advisor or investment banking services). None of the foregoing services involved the Fund, any of the other funds in the Pioneer Family of Funds or any other Pioneer entity sold by UniCredit in the Transaction. EY advised the Audit Committee that it had considered the matters described above and had concluded that such matters would not impair EY's ability to exercise objective and impartial judgment in connection with the audits of the financial statements of the Fund under the SEC and Public Company Accounting Oversight Board independence rules, and that a reasonable investor with knowledge of all relevant facts and circumstances would reach the same conclusion. Management and the Audit Committee considered these matters and discussed the matters with EY and, based upon EY's description of the matters and statements made by EY, Management and the Audit Committee believe that EY will be capable of exercising objective and impartial judgment in connection with the audits of the financial statements of the Fund, and Management further believes that a reasonable investor with knowledge of all relevant facts and circumstances would reach the same conclusion. 122 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 Trustees, Officers and Service Providers Trustees Officers Thomas J. Perna, Chairman Lisa M. Jones, President and Chief David R. Bock Executive Officer Benjamin M. Friedman Mark E. Bradley, Treasurer and Margaret B.W. Graham Chief Financial Officer Lisa M. Jones Christopher J. Kelley, Secretary and Lorraine H. Monchak Chief Legal Officer Marguerite A. Piret Fred J. Ricciardi Kenneth J. Taubes Investment Adviser and Administrator Amundi Pioneer Asset Management, Inc. Custodian and Sub-Administrator Brown Brothers Harriman & Co. Principal Underwriter Amundi Pioneer Distributor, Inc. Legal Counsel Morgan, Lewis & Bockius LLP Shareowner Services and Transfer Agent Boston Financial Data Services, Inc. Proxy Voting Policies and Procedures of the Fund are available without charge, upon request, by calling our toll free number (1-800-225-6292). Information regarding how the Fund voted proxies relating to portfolio securities during the most recent 12-month period ended June 30 is publicly available to shareowners at www.amundipioneer.com. This information is also available on the Securities and Exchange Commission's web site at www.sec.gov. Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 123 This page is for your notes. 124 Pioneer Multi-Asset Ultrashort Income Fund | Semiannual Report | 9/30/17 How to Contact Amundi Pioneer We are pleased to offer a variety of convenient ways for you to contact us for assistance or information. Call us for: -------------------------------------------------------------------------------- Account Information, including existing accounts, new accounts, prospectuses, applications and service forms 1-800-225-6292 FactFone(SM) for automated fund yields, prices, account information and transactions 1-800-225-4321 Retirement plans information 1-800-622-0176 Write to us: -------------------------------------------------------------------------------- Amundi Pioneer P.O. Box 55014 Boston, Massachusetts 02205-5014 Our toll-free fax 1-800-225-4240 Our internet e-mail address ask.amundipioneer@amundipioneer.com (for general questions about Amundi Pioneer only) Visit our web site: www.amundipioneer.com This report must be preceded or accompanied by a prospectus. The Fund files a complete schedule of investments with the Securities and Exchange Commission for the first and third quarters for each fiscal year on Form N-Q. Shareholders may view the filed Form N-Q by visiting the Commission's web site at http://www.sec.gov. The filed form may also be viewed and copied at the Commission's Public Reference Room in Washington, DC. Information regarding the operations of the Public Reference Room may be obtained by calling 1-800-SEC-0330. [LOGO] Amundi Pioneer ============== ASSET MANAGEMENT Amundi Pioneer Asset Management, Inc. 60 State Street Boston, MA 02109 www.amundipioneer.com Securities offered through Amundi Pioneer Funds Distributor, Inc. 60 State Street, Boston, MA 02109 Underwriter of Pioneer Mutual Funds, Member SIPC (C) 2017 Amundi Pioneer Asset Management 25249-06-1117 ITEM 2. CODE OF ETHICS. (a) Disclose whether, as of the end of the period covered by the report, the registrant has adopted a code of ethics that applies to the registrant's principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions, regardless of whether these individuals are employed by the registrant or a third party. If the registrant has not adopted such a code of ethics, explain why it has not done so. The registrant has adopted, as of the end of the period covered by this report, a code of ethics that applies to the registrant's principal executive officer, principal financial officer, principal accounting officer and controller. (b) For purposes of this Item, the term "code of ethics" means written standards that are reasonably designed to deter wrongdoing and to promote: (1) Honest and ethical conduct, including the ethical handling of actual or apparent conflicts of interest between personal and professional relationships; (2) Full, fair, accurate, timely, and understandable disclosure in reports and documents that a registrant files with, or submits to, the Commission and in other public communications made by the registrant; (3) Compliance with applicable governmental laws, rules, and regulations; (4) The prompt internal reporting of violations of the code to an appropriate person or persons identified in the code; and (5) Accountability for adherence to the code. (c) The registrant must briefly describe the nature of any amendment, during the period covered by the report, to a provision of its code of ethics that applies to the registrant's principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions, regardless of whether these individuals are employed by the registrant or a third party, and that relates to any element of the code of ethics definition enumerated in paragraph (b) of this Item. The registrant must file a copy of any such amendment as an exhibit pursuant to Item 10(a), unless the registrant has elected to satisfy paragraph (f) of this Item by posting its code of ethics on its website pursuant to paragraph (f)(2) of this Item, or by undertaking to provide its code of ethics to any person without charge, upon request, pursuant to paragraph (f)(3) of this Item. The registrant has made no amendments to the code of ethics during the period covered by this report. (d) If the registrant has, during the period covered by the report, granted a waiver, including an implicit waiver, from a provision of the code of ethics to the registrant's principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions, regardless of whether these individuals are employed by the registrant or a third party, that relates to one or more of the items set forth in paragraph (b) of this Item, the registrant must briefly describe the nature of the waiver, the name of the person to whom the waiver was granted, and the date of the waiver. Not applicable. (e) If the registrant intends to satisfy the disclosure requirement under paragraph (c) or (d) of this Item regarding an amendment to, or a waiver from, a provision of its code of ethics that applies to the registrant's principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions and that relates to any element of the code of ethics definition enumerated in paragraph (b) of this Item by posting such information on its Internet website, disclose the registrant's Internet address and such intention. Not applicable. (f) The registrant must: (1) File with the Commission, pursuant to Item 12(a)(1), a copy of its code of ethics that applies to the registrant's principal executive officer,principal financial officer, principal accounting officer or controller, or persons performing similar functions, as an exhibit to its annual report on this Form N-CSR (see attachment); (2) Post the text of such code of ethics on its Internet website and disclose, in its most recent report on this Form N-CSR, its Internet address and the fact that it has posted such code of ethics on its Internet website; or (3) Undertake in its most recent report on this Form N-CSR to provide to any person without charge, upon request, a copy of such code of ethics and explain the manner in which such request may be made. 	See Item 10(2) ITEM 3. AUDIT COMMITTEE FINANCIAL EXPERT. (a) (1) Disclose that the registrant's board of trustees has determined that the registrant either: (i) Has at least one audit committee financial expert serving on its audit committee; or (ii) Does not have an audit committee financial expert serving on its audit committee. The registrant's Board of Trustees has determined that the registrant has at least one audit committee financial expert. (2) If the registrant provides the disclosure required by paragraph (a)(1)(i) of this Item, it must disclose the name of the audit committee financial expert and whether that person is "independent." In order to be considered "independent" for purposes of this Item, a member of an audit committee may not, other than in his or her capacity as a member of the audit committee, the board of trustees, or any other board committee: (i) Accept directly or indirectly any consulting, advisory, or other compensatory fee from the issuer; or (ii) Be an "interested person" of the investment company as defined in Section 2(a)(19) of the Act (15 U.S.C. 80a-2(a)(19)). Ms. Marguerite A. Piret, an independent trustee, is such an audit committee financial expert. (3) If the registrant provides the disclosure required by paragraph (a)(1) (ii) of this Item, it must explain why it does not have an audit committee financial expert. Not applicable. ITEM 4. PRINCIPAL ACCOUNTANT FEES AND SERVICES. (a) Disclose, under the caption AUDIT FEES, the aggregate fees billed for each of the last two fiscal years for professional services rendered by the principal accountant for the audit of the registrant's annual financial statements or services that are normally provided by the accountant in connection with statutory and regulatory filings or engagements for those fiscal years. N/A (b) Disclose, under the caption AUDIT-RELATED FEES, the aggregate fees billed in each of the last two fiscal years for assurance and related services by the principal accountant that are reasonably related to the performance of the audit of the registrant's financial statements and are not reported under paragraph (a) of this Item. Registrants shall describe the nature of the services comprising the fees disclosed under this category. N/A (c) Disclose, under the caption TAX FEES, the aggregate fees billed in each of the last two fiscal years for professional services rendered by the principal accountant for tax compliance, tax advice, and tax planning. Registrants shall describe the nature of the services comprising the fees disclosed under this category. N/A (d) Disclose, under the caption ALL OTHER FEES, the aggregate fees billed in each of the last two fiscal years for products and services provided by the principal accountant, other than the services reported in paragraphs (a) through (c) of this Item. Registrants shall describe the nature of the services comprising the fees disclosed under this category. N/A (e) (1) Disclose the audit committee's pre-approval policies and procedures described in paragraph (c)(7) of Rule 2-01 of Regulation S-X. PIONEER FUNDS APPROVAL OF AUDIT, AUDIT-RELATED, TAX AND OTHER SERVICES PROVIDED BY THE INDEPENDENT AUDITOR SECTION I - POLICY PURPOSE AND APPLICABILITY The Pioneer Funds recognize the importance of maintaining the independence of their outside auditors. Maintaining independence is a shared responsibility involving Pioneer Investment Management, Inc ("PIM"), the audit committee and the independent auditors. The Funds recognize that a Fund's independent auditors: 1) possess knowledge of the Funds, 2) are able to incorporate certain services into the scope of the audit, thereby avoiding redundant work, cost and disruption of Fund personnel and processes, and 3) have expertise that has value to the Funds. As a result, there are situations where it is desirable to use the Fund's independent auditors for services in addition to the annual audit and where the potential for conflicts of interests are minimal. Consequently, this policy, which is intended to comply with Rule 210.2-01(C)(7), sets forth guidelines and procedures to be followed by the Funds when retaining the independent audit firm to perform audit, audit-related tax and other services under those circumstances, while also maintaining independence. Approval of a service in accordance with this policy for a Fund shall also constitute approval for any other Fund whose pre-approval is required pursuant to Rule 210.2-01(c)(7)(ii). In addition to the procedures set forth in this policy, any non-audit services that may be provided consistently with Rule 210.2-01 may be approved by the Audit Committee itself and any pre-approval that may be waived in accordance with Rule 210.2-01(c)(7)(i)(C) is hereby waived. Selection of a Fund's independent auditors and their compensation shall be determined by the Audit Committee and shall not be subject to this policy. SECTION II - POLICY ---------------- -------------------------------- ------------------------------------------------- SERVICE SERVICE CATEGORY DESCRIPTION SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES CATEGORY ---------------- -------------------------------- ------------------------------------------------- I. AUDIT Services that are directly o Accounting research assistance SERVICES related to performing the o SEC consultation, registration independent audit of the Funds statements, and reporting o Tax accrual related matters o Implementation of new accounting standards o Compliance letters (e.g. rating agency letters) o Regulatory reviews and assistance regarding financial matters o Semi-annual reviews (if requested) o Comfort letters for closed end offerings ---------------- -------------------------------- ------------------------------------------------- II. Services which are not o AICPA attest and agreed-upon procedures AUDIT-RELATED prohibited under Rule o Technology control assessments SERVICES 210.2-01(C)(4) (the "Rule") o Financial reporting control assessments and are related extensions of o Enterprise security architecture the audit services support the assessment audit, or use the knowledge/expertise gained from the audit procedures as a foundation to complete the project. In most cases, if the Audit-Related Services are not performed by the Audit firm, the scope of the Audit Services would likely increase. The Services are typically well-defined and governed by accounting professional standards (AICPA, SEC, etc.) ---------------- -------------------------------- ------------------------------------------------- ------------------------------------- ------------------------------------ AUDIT COMMITTEE APPROVAL POLICY AUDIT COMMITTEE REPORTING POLICY ------------------------------------- ------------------------------------ o "One-time" pre-approval o A summary of all such for the audit period for all services and related fees pre-approved specific service reported at each regularly subcategories. Approval of the scheduled Audit Committee independent auditors as meeting. auditors for a Fund shall constitute pre approval for these services. ------------------------------------- ------------------------------------ o "One-time" pre-approval o A summary of all such for the fund fiscal year within services and related fees a specified dollar limit (including comparison to for all pre-approved specified dollar limits) specific service subcategories reported quarterly. o Specific approval is needed to exceed the pre-approved dollar limit for these services (see general Audit Committee approval policy below for details on obtaining specific approvals) o Specific approval is needed to use the Fund's auditors for Audit-Related Services not denoted as "pre-approved", or to add a specific service subcategory as "pre-approved" ------------------------------------- ------------------------------------ SECTION III - POLICY DETAIL, CONTINUED ----------------------- --------------------------- ----------------------------------------------- SERVICE CATEGORY SERVICE CATEGORY SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES DESCRIPTION ----------------------- --------------------------- ----------------------------------------------- III. TAX SERVICES Services which are not o Tax planning and support prohibited by the Rule, o Tax controversy assistance if an officer of the Fund o Tax compliance, tax returns, excise determines that using the tax returns and support Fund's auditor to provide o Tax opinions these services creates significant synergy in the form of efficiency, minimized disruption, or the ability to maintain a desired level of confidentiality. ----------------------- --------------------------- ----------------------------------------------- ------------------------------------- ------------------------- AUDIT COMMITTEE APPROVAL POLICY AUDIT COMMITTEE REPORTING POLICY ------------------------------------- ------------------------- ------------------------------------- ------------------------- o "One-time" pre-approval o A summary of for the fund fiscal year all such services and within a specified dollar limit related fees 				 (including comparison 			 to specified dollar 			 limits) reported 			 quarterly. o Specific approval is needed to exceed the pre-approved dollar limits for these services (see general Audit Committee approval policy below for details on obtaining specific approvals) o Specific approval is needed to use the Fund's auditors for tax services not denoted as pre-approved, or to add a specific service subcategory as "pre-approved" ------------------------------------- ------------------------- SECTION III - POLICY DETAIL, CONTINUED ----------------------- --------------------------- ----------------------------------------------- SERVICE CATEGORY SERVICE CATEGORY SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES DESCRIPTION ----------------------- --------------------------- ----------------------------------------------- IV. OTHER SERVICES Services which are not o Business Risk Management support prohibited by the Rule, o Other control and regulatory A. SYNERGISTIC, if an officer of the Fund compliance projects UNIQUE QUALIFICATIONS determines that using the Fund's auditor to provide these services creates significant synergy in the form of efficiency, minimized disruption, the ability to maintain a desired level of confidentiality, or where the Fund's auditors posses unique or superior qualifications to provide these services, resulting in superior value and results for the Fund. ----------------------- --------------------------- ----------------------------------------------- --------------------------------------- ------------------------ AUDIT COMMITTEE APPROVAL POLICY AUDIT COMMITTEE REPORTING POLICY ------------------------------------- -------------------------- o "One-time" pre-approval o A summary of for the fund fiscal year within all such services and a specified dollar limit related fees 			 (including comparison 			 to specified dollar 				 limits) reported quarterly. o Specific approval is needed to exceed the pre-approved dollar limits for these services (see general Audit Committee approval policy below for details on obtaining specific approvals) o Specific approval is needed to use the Fund's auditors for "Synergistic" or "Unique Qualifications" Other Services not denoted as pre-approved to the left, or to add a specific service subcategory as "pre-approved" ------------------------------------- -------------------------- SECTION III - POLICY DETAIL, CONTINUED ----------------------- ------------------------- ----------------------------------------------- SERVICE CATEGORY SERVICE CATEGORY SPECIFIC PROHIBITED SERVICE SUBCATEGORIES DESCRIPTION ----------------------- ------------------------- ----------------------------------------------- PROHIBITED SERVICES Services which result 1. Bookkeeping or other services in the auditors losing related to the accounting records or independence status financial statements of the audit under the Rule. client* 2. Financial information systems design and implementation* 3. Appraisal or valuation services, fairness* opinions, or contribution-in-kind reports 4. Actuarial services (i.e., setting actuarial reserves versus actuarial audit work)* 5. Internal audit outsourcing services* 6. Management functions or human resources 7. Broker or dealer, investment advisor, or investment banking services 8. Legal services and expert services unrelated to the audit 9. Any other service that the Public Company Accounting Oversight Board determines, by regulation, is impermissible ----------------------- ------------------------- ----------------------------------------------- ------------------------------------------- ------------------------------ AUDIT COMMITTEE APPROVAL POLICY AUDIT COMMITTEE REPORTING POLICY ------------------------------------------- ------------------------------ o These services are not to be o A summary of all performed with the exception of the(*) services and related services that may be permitted fees reported at each if they would not be subject to audit regularly scheduled procedures at the audit client (as Audit Committee meeting defined in rule 2-01(f)(4)) level will serve as continual the firm providing the service. confirmation that has 				 not provided any restricted services. ------------------------------------------- ------------------------------ -------------------------------------------------------------------------------- GENERAL AUDIT COMMITTEE APPROVAL POLICY: o For all projects, the officers of the Funds and the Fund's auditors will each make an assessment to determine that any proposed projects will not impair independence. o Potential services will be classified into the four non-restricted service categories and the "Approval of Audit, Audit-Related, Tax and Other Services" Policy above will be applied. Any services outside the specific pre-approved service subcategories set forth above must be specifically approved by the Audit Committee. o At least quarterly, the Audit Committee shall review a report summarizing the services by service category, including fees, provided by the Audit firm as set forth in the above policy. -------------------------------------------------------------------------------- (2) Disclose the percentage of services described in each of paragraphs (b) through (d) of this Item that were approved by the audit committee pursuant to paragraph (c)(7)(i)(C) of Rule 2-01 of Regulation S-X. N/A (f) If greater than 50 percent, disclose the percentage of hours expended on the principal accountants engagement to audit the registrant's financial statements for the most recent fiscal year that were attributed to work performed by persons other than the principal accountant's full-time, permanent employees. N/A (g) Disclose the aggregate non-audit fees billed by the registrants accountant for services rendered to the registrant, and rendered to the registrants investment adviser (not including any sub-adviser whose role is primarily portfolio management and is subcontracted with or overseen by another investment adviser), and any entity controlling, controlled by, or under common control with the adviser that provides ongoing services to the registrant for each of the last two fiscal years of the registrant. N/A (h) Disclose whether the registrants audit committee of the board of trustees has considered whether the provision of non-audit services that were rendered to the registrants investment adviser (not including any subadviser whose role is primarily portfolio management and is subcontracted with or overseen by another investment adviser), and any entity controlling, controlled by, or under common control with the investment adviser that provides ongoing services to the registrant that were not pre-approved pursuant to paragraph (c)(7)(ii) of Rule 2-01 of Regulation S-X is compatible with maintaining the principal accountant's independence. The Fund's audit committee of the Board of Trustees has considered whether the provision of non-audit services that were rendered to the Affiliates (as defined) that were not pre- approved pursuant to paragraph (c)(7)(ii) of Rule 2-01 of Regulation S-X is compatible with maintaining the principal accountant's independence. ITEM 5. AUDIT COMMITTEE OF LISTED REGISTRANTS (a) If the registrant is a listed issuer as defined in Rule 10A-3 under the Exchange Act (17 CFR 240.10A-3), state whether or not the registrant has a separately-designated standing audit committee established in accordance with Section 3(a)(58)(A) of the Exchange Act (15 U.S.C. 78c(a)(58)(A)). If the registrant has such a committee, however designated, identify each committee member. If the entire board of directors is acting as the registrant's audit committee as specified in Section 3(a)(58)(B) of the Exchange Act (15 U.S.C. 78c(a)(58)(B)), so state. N/A (b) If applicable, provide the disclosure required by Rule 10A-3(d) under the Exchange Act (17 CFR 240.10A-3(d)) regarding an exemption from the listing standards for audit committees. N/A ITEM 6. SCHEDULE OF INVESTMENTS. File Schedule of Investments in securities of unaffiliated issuers as of the close of the reporting period as set forth in 210.1212 of Regulation S-X [17 CFR 210.12-12], unless the schedule is included as part of the report to shareholders filed under Item 1 of this Form. Included in Item 1 ITEM 7. DISCLOSURE OF PROXY VOTING POLICIES AND PROCEDURES FOR CLOSED-END MANAGEMENT INVESTMENT COMPANIES. A closed-end management investment company that is filing an annual report on this Form N-CSR must, unless it invests exclusively in non-voting securities, describe the policies and procedures that it uses to determine how to vote proxies relating to portfolio securities, including the procedures that the company uses when a vote presents a conflict between the interests of its shareholders, on the one hand, and those of the company's investment adviser; principal underwriter; or any affiliated person (as defined in Section 2(a)(3) of the Investment Company Act of 1940 (15 U.S.C. 80a-2(a)(3)) and the rules thereunder) of the company, its investment adviser, or its principal underwriter, on the other. Include any policies and procedures of the company's investment adviser, or any other third party, that the company uses, or that are used on the company's behalf, to determine how to vote proxies relating to portfolio securities. Not applicable to open-end management investment companies. ITEM 8. PORTFOLIO MANAGERS OF CLOSED-END MANAGEMENT INVESTMENT COMPANIES. (a) If the registrant is a closed-end management investment company that is filing an annual report on this Form N-CSR,provide the following information: (1) State the name, title, and length of service of the person or persons employed by or associated with the registrant or an investment adviser of the registrant who are primarily responsible for the day-to-day management of the registrant's portfolio ("Portfolio Manager"). Also state each Portfolio Manager's business experience during the past 5 years. Not applicable to open-end management investment companies. ITEM 9. PURCHASES OF EQUITY SECURITIES BY CLOSED-END MANAGEMENT INVESTMENT COMPANY AND AFFILIATED PURCHASERS. (a) If the registrant is a closed-end management investment company, in the following tabular format, provide the information specified in paragraph (b) of this Item with respect to any purchase made by or on behalf of the registrant or any affiliated purchaser, as defined in Rule 10b-18(a)(3) under the Exchange Act (17 CFR 240.10b-18(a)(3)), of shares or other units of any class of the registrant's equity securities that is registered by the registrant pursuant to Section 12 of the Exchange Act (15 U.S.C. 781). Not applicable to open-end management investment companies. ITEM 10. SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS. Describe any material changes to the procedures by which shareholders may recommend nominees to the registrant's board of directors, where those changes were implemented after the registrant last provided disclosure in response to the requirements of Item 407(c)(2)(iv) of Regulation S-R(17 CFR 229.407)(as required by Item 22(b)(15)) of Schedule 14A (17 CFR 240.14a-101), or this Item. There have been no material changes to the procedures by which the shareholders may recommend nominees to the registrant's board of directors since the registrant last provided disclosure in response to the requirements of Item 407(c)(2)(iv) of Regulation S-R of Schedule 14(A) in its definitive proxy statement, or this item. ITEM 11. CONTROLS AND PROCEDURES. (a) Disclose the conclusions of the registrant's principal executive and principal financials officers, or persons performing similar functions, regarding the effectiveness of the registrant's disclosure controls and procedures (as defined in Rule 30a-3(c) under the Act (17 CFR 270.30a-3(c))) as of a date within 90 days of the filing date of the report that includes the disclosure required by this paragraph, based on the evaluation of these controls and procedures required by Rule 30a-3(b) under the Act (17 CFR 270.30(a)-3(b) and Rules 13a-15(b) or 15d-15(b) under the Exchange Act (17 CFR 240.13a-15(b) or 240.15d-15(b)). The registrant's principal executive officer and principal financial officer have concluded that the registrant's disclosure controls and procedures are effective based on the evaluation of these controls and procedures as of a date within 90 days of the filing date of this report. (b) Disclose any change in the registrant's internal control over financial reporting (as defined in Rule 30a-3(d) under the Act (17CFR 270.30a-3(d)) that occured during the second fiscal quarter of the period covered by this report that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting. There were no significant changes in the registrant's internal control over financial reporting that occurred during the second fiscal quarter of the period covered by this report that have materially affected, or are reasonably likely to materially affect, the registrant's internal control over financial reporting. The registrant's principal executive officer and principal financial officer, however, voluntarily are reporting the following information: In August of 2006 the registrant's investment adviser enhanced its internal procedures for reporting performance information required to be included in prospectuses. Those enhancements involved additional internal controls over the appropriateness of performance data generated for this purpose. Such enhancements were made following an internal review which identified prospectuses relating to certain classes of shares of a limited number of registrants where, inadvertently, performance information not reflecting the deduction of applicable sales charges was included. Those prospectuses were revised, and the revised prospectuses were distributed to shareholders. ITEM 12. EXHIBITS. (a) File the exhibits listed below as part of this Form. Letter or number the exhibits in the sequence indicated. (1) Any code of ethics, or amendment thereto, that is the subject of the disclosure required by Item 2, to the extent that the registrant intends to satisfy the Item 2 requirements through filing of an exhibit. (2) A separate certification for each principal executive officer and principal financial officer of the registrant as required by Rule 30a-2(a) under the Act (17 CFR 270.30a-2(a)) , exactly as set forth below: Filed herewith. SIGNATURES [See General Instruction F] Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized. (Registrant) Pioneer Series Trust X By (Signature and Title)* /s/ Lisa M. Jones Lisa M. Jones, President & Chief Executive Officer Date November 29, 2017 Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated. By (Signature and Title)* /s/ Lisa M. Jones Lisa M. Jones, President & Chief Executive Officer Date November 29, 2017 By (Signature and Title)* /s/ Mark E. Bradley Mark E. Bradley, Treasurer & Chief Accounting & Financial Officer Date November 29, 2017 * Print the name and title of each signing officer under his or her signature.