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 811-21558 Pioneer Short Term Income Fund (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: August 31 Date of reporting period: September 1, 2016 through February 28, 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 Short Term Income Fund -------------------------------------------------------------------------------- Semiannual Report | February 28, 2017 -------------------------------------------------------------------------------- Ticker Symbols: Class A STABX Class C PSHCX Class C2 STIIX Class K STIKX Class Y PSHYX [LOGO] PIONEER Investments(R) visit us: us.pioneerinvestments.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 75 Notes to Financial Statements 84 Approval of Investment Advisory Agreement 96 Trustees, Officers and Service Providers 101 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 1 President's Letter Dear Shareowner, The 2016 calendar year featured many swings in market sentiment, both in the equity and fixed-income markets. After a slow start to the year, the markets began to rally in mid-February 2016 with a recovery in the prices of oil and other commodities, as well as slow, positive progress in U.S. employment figures. The rally persisted throughout much of the remaining 10 months of 2016, gaining further momentum in the second half of the year when U.S. gross domestic product (GDP) growth showed solid improvement during the third quarter and unemployment continued to decline. Finally, in November, the election of Donald Trump as the 45th President of the United States sparked a dramatic late-year market upturn that saw U.S. equities briefly climb to all-time highs. Speculation that the new Trump administration's policies would stimulate the U.S. economy through reduced taxes, less regulation, and increased government spending on infrastructure, fueled the year-end rally. For the full 12 months ended December 31, 2016, the Standard & Poor's 500 Index, a broad measure of U.S. stock market performance, returned a strong 11.9%. In bond markets, the Federal Reserve Board's (the Fed's) 0.25% hike in the Federal funds rate in December 2016, its first rate increase in a year, contributed to a sell-off in U.S. Treasuries. The pullback from Treasuries also derived from the market's increased inflation and growth expectations under the incoming Trump administration. Elsewhere within fixed income, corporate credit, particularly in the high-yield segment of the market, performed well over the fourth quarter and the full calendar year. US high-yield securities, as measured by the Bank of America Merrill Lynch US High Yield Index, returned a robust 17.5% for the 12 months ended December 31, 2016. The debt of energy-related issuers drove the strong performance within high yield, as the recovery in oil and other commodity prices, which began in February 2016, sparked a rally in the sector. Meanwhile, the Bloomberg Barclays U.S. Aggregate Bond Index, which tracks the performance of Treasury and agency issues, corporate bond issues, and mortgage-backed securities, returned 2.7% for the same 12-month period, reflecting the relative weakness in government bonds. The U.S. economy's underlying fundamentals seem solid, and growth prospects for 2017 appear healthy. However, we remain concerned about risks to the economy of potentially disruptive trade policies pursued by the Trump administration. Barring a damaging trade war, though, we anticipate the Fed will continue to hike short-term interest rates gradually during 2017. In addition, we expect the Fed to consider carefully the potential economic effects of any fiscal policies enacted by the new Trump administration and the Republican- controlled Congress. In that regard, we believe President Trump's economic policies, if they come to fruition, could help boost real GDP growth. However, the impact of Trump's policies on U.S. GDP may be greater in 2018 rather than in 2017. Still, even prior to the late-year "Trump rally," U.S. GDP growth appeared to be settling in at a sustainable annual pace of more than 2% as 2016 drew to a close, following some weaker performance in the first half of the year. Continued improvement in the employment market driven in part by gains in manufacturing output were among the factors behind the bounce-back in GDP. 2 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 While economic conditions inside the U.S. appear solid, many economies around the world continue to experience slow growth rates. Moreover, several countries in various regions face a number of challenges in 2017 and beyond, including the shifting geopolitics driving "Brexit" - the United Kingdom's pending exit from the European Union - as well as related populist movements in Europe, limited productivity gains, aging populations, and transitioning economic models in China and other emerging markets. In recent years, global central banks have kept interest rates at close to zero in an effort to stimulate economic growth. While financial markets often benefited from the low rates, it now appears that those policies may be losing their effectiveness, leaving central banks little room to maneuver going forward. Moreover, the low interest rates have caused government bond yields to plummet, presenting a dilemma for the income-oriented investor. Against this backdrop of still-low global interest rates, shifting priorities of central banks, evolving demographics, and numerous geopolitical concerns, we believe investors are likely to face ongoing challenges and much uncertainty when it comes to finding opportunities for both income and capital appreciation. While much has been made of passive investing as a possible source of stability in this uncertain environment, it is our view that all investment decisions are active choices. Throughout Pioneer's history, we have believed in the importance of active management. During challenging market conditions, we view the value of active management as even more compelling. Our experienced and tenured investment teams focus on identifying value across global markets using proprietary research, careful risk management, and a long-term perspective. We believe our shareowners can benefit from the experience and tenure of our investment teams as well as the insights generated from our extensive research process. 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 President and CEO Pioneer Investment Management USA Inc. February 28, 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 Short Term Income Fund | Semiannual Report | 2/28/17 3 Portfolio Management Discussion | 2/28/17 In the following interview, portfolio managers Charles Melchreit and Seth Roman discuss the factors that influenced Pioneer Short Term Income Fund's performance for the six-month period ended February 28, 2017. Mr. Melchreit, Director of Investment Grade, a senior vice president, and portfolio manager at Pioneer, and Mr. Roman, a vice president and portfolio manager at Pioneer, are responsible for the day-today management of the Fund. Q How did the Fund perform during the six-month period ended February 28, 2017? A Pioneer Short Term Income Fund's Class A shares returned 0.82% at net asset value during the six-month period ended February 28, 2017, while the Fund's benchmark, the Bloomberg Barclays One- to Three-Year Government/Credit Bond Index (the Bloomberg Barclays Index), returned 0.08%. During the same period, the average return of the 339 mutual funds in Lipper's Short Investment-Grade Debt Funds category was 0.55%, and the average return of the 530 mutual funds in Morningstar's Short-Term Bond Funds category was 0.27%. Q How would you describe the market environment for fixed-income investors over the six-month period ended February 28, 2017? A Entering the period in September 2016, investor sentiment towards the credit-sensitive sectors was supported by moderate U.S. economic growth rates, improved employment conditions and consumer balance sheets, and solid corporate earnings results. U.S. Treasury yields rose sharply, and riskier assets, including equities and credit-oriented areas of the fixed- income market, rallied following the results of the November U.S. elections, which left the Republicans with unified control of the White House and both houses of Congress. Investors anticipated the implementation of pro-growth, business-friendly policies from the incoming Trump administration, including lower corporate tax rates, reduced regulatory oversight, and increased infrastructure spending. In December 2016, the U.S. Federal Reserve (the Fed) implemented its long-awaited, second incremental increase in short-term interest rates, one year after raising rates the first time, while also signaling the likelihood of 4 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 two or three more rate hikes in 2017 should economic data meet expectations. During the six-month period ended February 28, 2017, Treasury yields finished notably higher across different maturities, and the yield curve steepened. To illustrate, the two-year Treasury yield rose by 42 basis points (bps) during the period, from 0.80% to 1.22%, the five-year Treasury yield rose by 70 bps, from 1.19% to 1.89%, and the 10-year Treasury yield rose by 78 bps, from 1.58% to 2.36%. (A basis point is equal to 0.01%). In that environment, credit-sensitive segments of the bond market significantly outperformed Treasuries over the six-month period. Q Can you review the investment strategies that affected the Fund's benchmark-relative performance, either positively or negatively, during the six-month period ended February 28, 2017? A The Fund solidly outperformed the Bloomberg Barclays Index during the six-month period, with several factors contributing positively to benchmark-relative returns. The Fund's significant underweighting of U.S. Treasuries compared with the benchmark aided relative performance, as spread sectors outperformed Treasuries during the period. (Credit spreads are commonly defined as the differences in yield between Treasuries and other types of fixed-income securities with similar maturities.) In addition, we overweighted the Fund's non-Treasury holdings in securities that were more price-sensitive to changes in credit spreads, a stance that benefited benchmark-relative performance as spreads tightened over the six months. Other solid contributors to benchmark-relative performance included the portfolio's exposures to a number of spread sectors that are not components of the Bloomberg Barclays Index. In that vein, the Fund's allocation to the securitized sectors was a leading driver of positive benchmark-relative returns. In particular, an allocation to asset-backed securities (ABS), such as those backed by home equity loans, auto loans, and credit card receivables boosted relative results. Within ABS, we have viewed issues backed by credit card receivables as particular beneficiaries of the ongoing improvement in consumer balance sheets, but have taken a more cautious stance with respect to sub-prime auto loans. Also within the Fund's Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 5 securitized holdings, an allocation to floating-rate commercial mortgage- backed securities contributed positively to benchmark-relative performance, primarily due to holdings of hospitality-related issues. Exposure to floating-rate bank loans was another notable contributor to the Fund's benchmark-relative outperformance, as the asset class benefited from continued strong fundamentals and low default rates, as well as from the prospects for rising interest rates. With most bank loans trading over par (face) value, we are taking care to manage the Fund's exposure to refinancing risk. The Fund also maintained a modest position in so-called "catastrophe" (CAT) bonds, which are used by insurers to spread out the risk of having to pay claims on a major disaster, such as a flood or earthquake. We maintained this allocation principally as a means of adding diversification to the portfolio, but the CAT bonds helped the Fund's benchmark-relative results during the period as investors continued to be attracted to the asset class because of the available yields as well as the lack of correlation to traditional credit risk. Moreover, there was little activity in terms of natural disasters and associated claims pay-outs over the six-month period. The Fund's exposure to corporate credit was another positive factor in its benchmark-relative performance over the six months. Within that allocation, the Fund was overweight financials, which benefited from rising interest rates and a steeper yield curve. Within financials, we have maintained a portfolio tilt toward U.S. banks, due to the concerns surrounding the health of the European banking sector. Finally, the Fund's shorter-duration stance relative to the benchmark contributed to performance, as we decided to focus on securities with shorter maturities in order to minimize portfolio exposure to any future rise in interest rates. While the duration positioning aided benchmark- relative performance, it did act as a constraint on the Fund's income-generation during the period. (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.) 6 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 On the negative side, the main drag on the Fund's benchmark-relative returns during the period was an allocation to non-agency collateralized mortgage obligations (CMOs). The CMOs hurt the Fund's relative performance as interest rates rose and durations for the holdings extended at a time when investors were seeking to reduce interest-rate risk. We are maintaining the Fund's allocation to non-agency CMOs, however, as we like the technical supply/demand backdrop for the asset class, the yields, and the diversification CMOs add to the portfolio. Q Can you discuss the factors that affected the Fund's income-generation (or yield), either positively or negatively, during the six-month period ended February 28, 2017? A The Fund has been conservatively positioned with respect to overall portfolio duration and corresponding sensitivity to changes in interest rates, given the outlook for the Fed to continue raising the Federal funds rate. As noted earlier, in maintaining the short-duration position, we accepted the loss of some income-generation by the portfolio during the period in exchange for improved price stability should interest rates rise. Conversely, the yields on many floating-rate issues in the Fund were reset higher during the period in the wake of the Fed's December 2016 rate increase. Q What role did derivatives play in the Fund's investment process and results during the six-month period ended February 28, 2017? A We used futures contracts during the period in an effort to manage overall portfolio duration and to express views on relative value along the yield curve. The use of derivatives did not have a material impact on the Fund's performance. Q What is your assessment of the current climate for fixed-income investing, and how is the Fund positioned with regard to that assessment? A We continue to manage the Fund based on the expectation that interest rates are headed higher, with a below-benchmark overall duration and approximately half of the Fund's total investment portfolio allocated to floating-rate securities. In broad terms, we prefer a portfolio positioning that could limit any negative effects on the Fund's benchmark-relative performance should the economy outperform and the number of future Fed rate hikes exceeds current expectations. The portfolio's overall duration as of February 28, 2017, was 1.4 years, compared with a duration of 1.9 years for the Bloomberg Barclays Index. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 7 In addition, despite the recent uptick in yields, we see little value in U.S. Treasuries and are maintaining only a modest Fund position in the asset class, mainly to supply liquidity should future market conditions dictate such a need. We view credit-sector fundamentals as strong, based on the positive flow of U.S. economic data and on the fiscal policy proposals likely to emerge from the new administration. At the same time, credit spreads are tight by historical standards, and, rather than simply reaching for yield, we are closely monitoring the portfolio's positions to ensure that the Fund is receiving appropriate compensation for the assumed risk. In broad terms, the portfolio has an up-in-quality bias within each credit sector. As always, we will continue to monitor macroeconomic factors that could have the potential to affect the markets, while remaining principally focused on adding value to the Fund at the individual security level. Please refer to the Schedule of Investments on pages 19-74 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. 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. Investments in the Fund are subject to possible loss due to the financial failure of the issuers of the underlying securities and their inability to meet their debt obligations. 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. Investments in high-yield or lower-rated securities are subject to greater-than- average price volatility, illiquidity and possibility of default. The securities issued by U.S. government sponsored entities (i.e. Fannie Mae, Freddie Mac) are neither guaranteed nor issued by the U.S. government. 8 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 The portfolio 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. Investing in foreign and/or emerging markets securities involves risks relating to interest rates, currency exchange rates, economic, and political conditions. 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 Pioneer Investments 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 not a guarantee of future results. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 9 Portfolio Summary | 2/28/17 Portfolio Diversification -------------------------------------------------------------------------------- (As a percentage of total investment portfolio)* [THE FOLLOWING DATA WAS REPRESENTED AS A PIE CHART IN THE PRINTED MATERIAL] Collateralized Mortgage Obligations 28.7% U.S. Corporate Bonds 28.4% Asset Backed Securities 12.5% International Corporate Bonds 10.8% U.S. Government Securities 10.3% Senior Secured Loans 5.8% Temporary Cash Investment 2.5% Municipal Bonds 1.0% * Includes investments in insurance linked securities totaling 6.1% of total investment portfolio. 10 Largest Holdings** -------------------------------------------------------------------------------- 1. United States Treasury Notes, 1.125%, 8/31/21 0.70% -------------------------------------------------------------------------------- 2. Everglades Re, LTD., Floating Rate Note, 4/28/17 0.60 -------------------------------------------------------------------------------- 3. United States Treasury Notes, 2.25%, 7/31/21 0.59 -------------------------------------------------------------------------------- 4. United States Treasury Notes, 1.625% 6/30/19 0.49 -------------------------------------------------------------------------------- 5. United States Treasury Notes, 2.00% 8/31/21 0.45 -------------------------------------------------------------------------------- 6. United States Treasury Notes, 1.50% 12/31/18 0.44 -------------------------------------------------------------------------------- 7. Mississippi Business Finance Corp., Floating Rate Note, 11/01/35 0.42 -------------------------------------------------------------------------------- 8. United States Treasury Notes, 1.125%, 7/31/21 0.40 -------------------------------------------------------------------------------- 9. United States Treasury Notes, 0.75% 9/30/18 0.40 -------------------------------------------------------------------------------- 10. United States Treasury Notes, 1.25% 11/30/18 0.35 -------------------------------------------------------------------------------- ** 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 Short Term Income Fund | Semiannual Report | 2/28/17 Prices and Distributions | 2/28/17 Net Asset Value per Share -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Class 2/28/17 8/31/16 -------------------------------------------------------------------------------- A $9.53 $9.56 -------------------------------------------------------------------------------- C $9.51 $9.54 -------------------------------------------------------------------------------- C2 $9.51 $9.55 -------------------------------------------------------------------------------- K $9.54 $9.57 -------------------------------------------------------------------------------- Y $9.51 $9.54 -------------------------------------------------------------------------------- Distributions per Share: 9/1/16-2/28/17 -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Net Investment Short-Term Long-Term Class Income Capital Gains Capital Gains -------------------------------------------------------------------------------- A $0.1080 $-- $-- -------------------------------------------------------------------------------- C $0.0958 $-- $-- -------------------------------------------------------------------------------- C2 $0.0960 $-- $-- -------------------------------------------------------------------------------- K $0.1230 $-- $-- -------------------------------------------------------------------------------- Y $0.1181 $-- $-- -------------------------------------------------------------------------------- The Bloomberg Barclays One- to Three-Year Government/Credit Index is an unmanaged measure of the performance of the short-term (1 to 3 years) government and investment-grade corporate bond markets. Index returns are calculated monthly, 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 Short Term Income Fund | Semiannual Report | 2/28/17 11 Performance Update | 2/28/17 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 Short Term Income Fund at public offering price during the periods shown, compared to that of the Bloomberg Barclays One- to Three-Year Government/Credit Index. Average Annual Total Returns (As of February 28, 2017) -------------------------------------------------------------------------------- Bloomberg Barclays Net Public One- to Asset Offering Three-Year Value Price Government/ Period (NAV) (POP) Credit Index -------------------------------------------------------------------------------- 10 Years 2.72% 2.46% 2.37% 5 Years 1.69 1.17 0.92 1 Year 2.33 -0.19 1.02 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated December 31, 2016) -------------------------------------------------------------------------------- Gross -------------------------------------------------------------------------------- 0.79% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Bloomberg Barclays Pioneer Short Term One- to Three-Year Income Fund Government/Credit Index 2/07 $ 9,750 $10,000 2/08 $10,240 $10,853 2/09 $ 9,813 $11,109 2/10 $10,999 $11,638 2/11 $11,457 $11,869 2/12 $11,726 $12,077 2/13 $12,138 $12,205 2/14 $12,302 $12,305 2/15 $12,416 $12,403 2/16 $12,458 $12,516 2/17 $12,749 $12,644 Call 1-800-225-6292 or visit us.pioneerinvestments.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. POP returns reflect deduction of maximum 2.50% sales charge. NAV 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. 12 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 Performance Update | 2/28/17 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 Short Term Income Fund during the periods shown, compared to that of the Bloomberg Barclays One- to Three-Year Government/Credit Index. Average Annual Total Returns (As of February 28, 2017) -------------------------------------------------------------------------------- Bloomberg Barclays One- to Three-Year If If Government/ Period Held Redeemed Credit Index -------------------------------------------------------------------------------- 10 Years 2.10% 2.10% 2.37% 5 Years 1.30 1.30 0.92 1 Year 2.07 2.07 1.02 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated December 31, 2016) -------------------------------------------------------------------------------- Gross -------------------------------------------------------------------------------- 1.05% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Bloomberg Barclays Pioneer Short Term One- to Three-Year Income Fund Government/Credit Index 2/07 $10,000 $10,000 2/08 $10,413 $10,853 2/09 $ 9,897 $11,109 2/10 $11,002 $11,638 2/11 $11,372 $11,869 2/12 $11,541 $12,077 2/13 $11,863 $12,205 2/14 $11,967 $12,305 2/15 $12,059 $12,403 2/16 $12,059 $12,516 2/17 $12,309 $12,644 Call 1-800-225-6292 or visit us.pioneerinvestments.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 were subject to a 1% contingent deferred sales charge (CDSC) through July 31, 2013. The CDSC for Class C shares was eliminated effective August 1, 2013. "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 Short Term Income Fund | Semiannual Report | 2/28/17 13 Performance Update | 2/28/17 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 Short Term Income Fund during the periods shown, compared to that of the Bloomberg Barclays One- to Three-Year Government/Credit Index. Average Annual Total Returns (As of February 28, 2017) -------------------------------------------------------------------------------- Bloomberg Barclays One- to Three-Year If If Government/ Period Held Redeemed Credit Index -------------------------------------------------------------------------------- 10 Years 2.11% 2.11% 2.37% 5 Years 1.32 1.32 0.92 1 Year 2.09 2.09 1.02 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated December 31, 2016 -------------------------------------------------------------------------------- Gross -------------------------------------------------------------------------------- 1.04% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Bloomberg Barclays Pioneer Short Term One- to Three-Year Income Fund Government/Credit Index 2/07 $10,000 $10,000 2/08 $10,413 $10,853 2/09 $ 9,897 $11,109 2/10 $11,002 $11,638 2/11 $11,372 $11,869 2/12 $11,541 $12,077 2/13 $11,863 $12,205 2/14 $11,985 $12,305 2/15 $12,068 $12,403 2/16 $12,069 $12,516 2/17 $12,321 $12,644 Call 1-800-225-6292 or visit us.pioneerinvestments.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 periods prior to the inception 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. "If Held" results represent the percent change in net asset value per share. Class C2 shares held for less than one year are also subject to a 1% contingent deferred sales charge (CDSC). "If Redeemed" returns for Class C2 shares shown in the table above reflect the deduction of the 1% CDSC. Class C2 shares held for one year or more are not subject to a CDSC. 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. 14 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 Performance Update | 2/28/17 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 Short Term Income Fund during the periods shown, compared to that of the Bloomberg Barclays One- to Three-Year Government/Credit Index. Average Annual Total Returns (As of February 28, 2017) -------------------------------------------------------------------------------- Bloomberg Barclays Net One- to Asset Three-Year Value Government/ Period (NAV) Credit Index -------------------------------------------------------------------------------- 10 Years 2.80% 2.37% 5 Years 1.85 0.92 1 Year 2.74 1.02 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated December 31, 2016) -------------------------------------------------------------------------------- Gross -------------------------------------------------------------------------------- 0.50% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $5 Million Investment Bloomberg Barclays Pioneer Short Term One- to Three-Year Income Fund Government/Credit Index 2/07 $5,000,000 $5,000,000 2/08 $5,250,408 $5,426,542 2/09 $5,031,795 $5,554,697 2/10 $5,639,995 $5,819,099 2/11 $5,874,844 $5,934,458 2/12 $6,012,653 $6,038,489 2/13 $6,223,863 $6,102,718 2/14 $6,307,875 $6,152,433 2/15 $6,371,673 $6,201,692 2/16 $6,414,147 $6,258,081 2/17 $6,590,198 $6,321,905 Call 1-800-225-6292 or visit us.pioneerinvestments.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 1, 2014, 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 1, 2014, 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 Short Term Income Fund | Semiannual Report | 2/28/17 15 Performance Update | 2/28/17 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 Short Term Income Fund during the periods shown, compared to that of the Bloomberg Barclays One- to Three-Year Government/Credit Index. Average Annual Total Returns (As of February 28, 2017) -------------------------------------------------------------------------------- Bloomberg Barclays Net One- to Asset Three-Year Value Government/ Period (NAV) Credit Index -------------------------------------------------------------------------------- 10 Years 2.99% 2.37% 5 Years 1.94 0.92 1 Year 2.65 1.02 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated December 31, 2016) -------------------------------------------------------------------------------- Gross -------------------------------------------------------------------------------- 0.59% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $5 Million Investment Bloomberg Barclays Pioneer Short Term One- to Three-Year Income Fund Government/Credit Index 2/07 $5,000,000 $5,000,000 2/08 $5,264,614 $5,426,542 2/09 $5,052,566 $5,554,697 2/10 $5,686,438 $5,819,099 2/11 $5,943,637 $5,934,458 2/12 $6,099,173 $6,038,489 2/13 $6,333,946 $6,102,718 2/14 $6,438,213 $6,152,433 2/15 $6,513,132 $6,201,692 2/16 $6,542,224 $6,258,081 2/17 $6,715,671 $6,321,905 Call 1-800-225-6292 or visit us.pioneerinvestments.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 Short Term Income Fund | Semiannual Report | 2/28/17 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 Short Term Income Fund Based on actual returns from September 1, 2016, through February 28, 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 9/1/16 -------------------------------------------------------------------------------- Ending Account $1,008.20 $1,006.90 $1,005.90 $1,009.80 $1,009.30 Value (after expenses) on 2/28/17 -------------------------------------------------------------------------------- Expenses Paid $ 4.08 $ 5.22 $ 5.22 $ 2.44 $ 3.04 During Period* -------------------------------------------------------------------------------- * Expenses are equal to the Fund's annualized net expense ratio of 0.82%, 1.05%, 1.05%, 0.49%, and 0.61% 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 181/365, (to reflect the one-half year period). Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 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 Short Term Income Fund Based on a hypothetical 5% return per year before expenses, reflecting the period from September 1, 2016, through February 28, 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 9/1/16 -------------------------------------------------------------------------------- Ending Account $1,020.73 $1,019.59 $1,019.59 $1,022.36 $1,021.77 Value (after expenses) on 2/28/17 -------------------------------------------------------------------------------- Expenses Paid $ 4.11 $ 5.26 $ 5.26 $ 2.46 $ 3.06 During Period* -------------------------------------------------------------------------------- * Expenses are equal to the Fund's annualized net expense ratio of 0.82%, 1.05%, 1.05%, 0.49%, and 0.61% 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 181/365, (to reflect the one-half year period). 18 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 Schedule of Investments | 2/28/17 (unaudited) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- ASSET BACKED SECURITIES -- 12.8% ENERGY -- 0.4% Oil & Gas Exploration & Production -- 0.4% 499,954 AXIS Equipment Finance Receivables IV LLC, 4.67%, 3/20/22 (144A) $ 492,671 106,629 1.52 Equity One Mortgage Pass-Through Trust 2003-1, Floating Rate Note, 8/25/33 106,335 750,000 2.28 NCF Dealer Floorplan Master Trust, Floating Rate Note, 10/20/20 (144A) 742,696 661,115 PRPM 2016-1 LLC, 4.0%, 9/27/21 (Step) (144A) 658,510 -------------- $ 2,000,212 -------------- Total Energy $ 2,000,212 ----------------------------------------------------------------------------------------------------- TRANSPORTATION -- 0.1% Trucking -- 0.1% 71,605 1.17 Hertz Fleet Lease Funding LP, Floating Rate Note, 4/10/28 (144A) $ 71,590 500,000 4.12 Hertz Fleet Lease Funding LP, Floating Rate Note, 4/10/30 (144A) 517,711 -------------- $ 589,301 -------------- Total Transportation $ 589,301 ----------------------------------------------------------------------------------------------------- CONSUMER SERVICES -- 0.0%+ Hotels, Resorts & Cruise Lines -- 0.0%+ 39,195 Westgate Resorts 2012-A LLC, 3.75%, 8/20/25 (144A) $ 39,114 216,516 Westgate Resorts 2014-1 LLC, 2.15%, 12/20/26 (144A) 214,419 -------------- $ 253,533 -------------- Total Consumer Services $ 253,533 ----------------------------------------------------------------------------------------------------- HEALTH CARE EQUIPMENT & SERVICES -- 0.1% Health Care Distributors -- 0.1% 300,000 OneMain Financial Issuance Trust 2015-1, 3.19%, 3/18/26 (144A) $ 302,680 -------------- Total Health Care Equipment & Services $ 302,680 ----------------------------------------------------------------------------------------------------- BANKS -- 10.8% Thrifts & Mortgage Finance -- 10.8% 309,945 1.00 321 Henderson Receivables I LLC, Floating Rate Note, 11/15/40 (144A) $ 294,230 46,476 Access Point Funding I 2015-A LLC, 2.61%, 4/15/20 (144A) 46,694 19,717 1.38 Accredited Mortgage Loan Trust 2005-2, Floating Rate Note, 7/25/35 19,691 111,152 1.50 Aegis Asset Backed Securities Trust Mortgage Pass- Through Ctfs Series 2004-3, Floating Rate Note, 9/25/34 110,863 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 19 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 36,190 1.88 Aegis Asset Backed Securities Trust Mortgage Pass- Through Ctfs Series 2004-3, Floating Rate Note, 9/25/34 $ 36,159 36,631 1.15 Aegis Asset Backed Securities Trust Mortgage Pass- Through Ctfs Ser 2005-4, Floating Rate Note, 10/25/35 36,365 665,000 2.12 American Homes 4 Rent 2014-SFR1, Floating Rate Note, 6/17/31 662,746 439,940 1.20 Ameriquest Mortgage Securities Inc Asset-Backed Pass-Through Ctfs Ser 2004-R6, Floating Rate Note, 7/25/34 435,439 288,414 1.11 Ameriquest Mortgage Securities, Inc., Asset Backed Pass-Through Ctfs Series 2005-R11, Floating Rate Note, 1/25/36 285,657 1,894 4.53 Ameriquest Mortgage Securities, Inc., Asset-Backed Pass-Through Ctfs Series 03-AR3, Floating Rate Note, 6/25/33 1,893 44,670 1.45 Ameriquest Mortgage Securities, Inc., Asset-Backed Pass-Through Ctfs Series 2005-R1, Floating Rate Note, 3/25/35 44,677 510,000 Ascentium Equipment Receivables 2015-1 LLC, 3.24%, 1/10/22 (144A) 514,048 200,000 Ascentium Equipment Receivables 2015-1 LLC, 5.92%, 6/12/23 (144A) 206,358 200,000 Ascentium Equipment Receivables 2016-2 Trust, 4.2%, 9/10/22 (144A) 197,542 219,562 4.30 Asset Backed Securities Corp Home Equity Loan Trust Series 2003-HE1, Floating Rate Note, 1/15/33 221,445 158,124 1.50 Asset Backed Securities Corp Home Equity Loan Trust Series 2004-HE6, Floating Rate Note, 9/25/34 157,294 8,313 1.48 Asset Backed Securities Corp Home Equity Loan Trust Series 2005-HE3, Floating Rate Note, 4/25/35 8,302 30,041 0.98 Asset Backed Securities Corp Home Equity Loan Trust Series AEG 2006-HE1, Floating Rate Note, 1/25/36 29,471 299,996 Axis Equipment Finance Receivables III LLC, 3.41%, 4/20/20 (144A) 286,851 782,989 Axis Equipment Finance Receivables III LLC, 5.27%, 5/20/20 (144A) 750,691 600,000 1.16 BA Credit Card Trust, Floating Rate Note, 10/15/21 602,837 500,000 1.11 Barclays Dryrock Issuance Trust, Floating Rate Note, 3/16/20 500,185 148,807 4.91 Bayview Financial Asset Trust 2003-A, Floating Rate Note, 2/25/33 (144A) 149,015 The accompanying notes are an integral part of these financial statements. 20 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 509,944 1.53 Bayview Financial Mortgage Pass-Through Trust 2005-C, Floating Rate Note, 6/28/44 $ 508,676 31,013 1.08 Bayview Financial Mortgage Pass-Through Trust 2006-B, Floating Rate Note, 4/28/36 30,923 4,346 1.05 Bayview Financial Mortgage Pass-Through Trust 2006-B, Floating Rate Note, 4/28/36 4,333 221,717 1.53 Bear Stearns Asset Backed Securities I Trust 2005-FR1, Floating Rate Note, 6/25/35 220,446 13,706 1.98 Bear Stearns Asset Backed Securities Trust 2004-2, Floating Rate Note, 8/25/34 13,721 103,063 1.27 Bear Stearns Asset Backed Securities Trust 2006-SD2, Floating Rate Note, 6/25/36 101,280 99,119 1.78 Bear Stearns Structured Products Trust 2007-EMX1, Floating Rate Note, 3/25/37 (144A) 98,401 894,561 CAM Mortgage Trust 2016-2, 3.25%, 6/15/57 (Step) (144A) 888,270 540,000 CarMax Auto Owner Trust 2013-3, 2.15%, 5/15/19 542,053 528,764 0.96 Carrington Mortgage Loan Trust Series 2006-OPT1, Floating Rate Note, 12/26/35 519,027 306,124 1.40 CDC Mortgage Capital Trust 2002-HE1, Floating Rate Note, 1/25/33 284,756 62,928 1.32 Chase Funding Trust Series 2003-3, Floating Rate Note, 4/25/33 57,290 155,197 Chase Funding Trust Series 2003-6, 4.277%, 11/27/34 (Step) 158,575 200,000 1.92 Chesapeake Funding II LLC, Floating Rate Note, 3/15/28 (144A) 201,072 500,000 1.93 Citibank Credit Card Issuance Trust, Floating Rate Note, 1/23/20 504,716 200,000 1.20 Citibank Credit Card Issuance Trust, Floating Rate Note, 9/10/20 200,804 61,079 0.98 Citigroup Mortgage Loan Trust 2006-SHL1, Floating Rate Note, 11/27/45 (144A) 60,944 46,830 1.80 Citigroup Mortgage Loan Trust, Inc., Floating Rate Note, 11/25/34 45,437 125,569 1.53 Citigroup Mortgage Loan Trust, Inc., Floating Rate Note, 5/25/35 (144A) 125,133 157,848 CNH Equipment Trust 2013-B, 0.99%, 11/15/18 157,809 186,041 Colony American Finance 2015-1, Ltd., 2.896%, 10/18/47 (144A) 185,517 700,000 2.62 Colony American Homes 2014-1, Floating Rate Note, 5/19/31 (144A) 700,030 200,000 3.42 Colony Starwood Homes 2016-1 Trust, Floating Rate Note, 7/17/33 (144A) 204,042 62,689 Conn's Receivables Funding 2016-A LLC, 4.68%, 4/16/18 (144A) 62,812 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 21 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 345,507 Conn's Receivables Funding 2016-B LLC, 3.73%, 10/15/18 (144A) $ 346,601 591,846 2.27 Conseco Finance Home Equity Loan Trust 2002-C, Floating Rate Note, 4/15/32 581,872 21,497 Consumer Credit Origination Loan Trust 2015-1, 2.82%, 3/15/21 (144A) 21,504 384,528 1.68 Countrywide Asset-Backed Certificates, Floating Rate Note, 3/25/35 381,298 359,128 1.88 Countrywide Asset-Backed Certificates, Floating Rate Note, 9/25/34 (144A) 346,074 300,000 CPS Auto Receivables Trust 2016-C, 2.48%, 9/15/20 (144A) 300,002 250,000 Credit Acceptance Auto Loan Trust 2016-2, 4.29%, 11/15/24 (144A) 256,686 68,771 1.05 Credit Suisse Mortgage Capital Certificates, Floating Rate Note, 10/27/36 (144A) 68,229 499,510 CRG Issuer 2015-1, 4.07%, 7/11/22 (144A) 495,764 1,110,153 1.01 CWABS Asset-Backed Certificates Trust 2005-14, Floating Rate Note, 4/25/36 1,102,871 161,832 Diamond Resorts Owner Trust 2014-1, 2.54%, 5/20/27 (144A) 159,810 291,137 2.58 DRB Prime Student Loan Trust 2016-B, Floating Rate Note, 6/25/40 (144A) 297,314 400,000 Drive Auto Receivables Trust 2016-C, 3.02%, 11/15/21 (144A) 404,623 378,545 3.87 Drug Royalty II LP 2, Floating Rate Note, 7/15/23 (144A) 381,099 400,000 DT Auto Owner Trust 2017-1, 2.26%, 2/15/21 (144A) 399,960 51,366 1.68 Ellington Loan Acquisition Trust 2007-1, Floating Rate Note, 5/26/37 (144A) 51,298 400,000 Elm 2016-1 Trust, 4.163%, 6/20/25 (144A) 401,312 500,000 Engs Commercial Finance Trust 2016-1, 3.45%, 3/22/22 (144A) 490,030 400,000 Enterprise Fleet Financing LLC, 1.74%, 2/22/22 (144A) 399,263 148,998 4.14 Equity One Mortgage Pass-Through Trust 2004-1, Floating Rate Note, 4/25/34 149,274 486,710 4.62 Equity One Mortgage Pass-Through Trust 2004-2, Floating Rate Note, 7/25/34 488,654 1,401,584 1.02 Fieldstone Mortgage Investment Trust Series 2005-3, Floating Rate Note, 2/25/36 1,377,293 46,892 2.28 First Franklin Mortgage Loan Trust 2002-FFA, Floating Rate Note, 9/25/32 47,483 277,082 2.08 First Franklin Mortgage Loan Trust 2003-FFC, Floating Rate Note, 11/25/32 273,092 56,647 1.54 First Franklin Mortgage Loan Trust 2005-FFH3, Floating Rate Note, 9/25/35 56,624 300,000 First Investors Auto Owner Trust 2013-3, 2.32%, 10/15/19 (144A) 300,483 The accompanying notes are an integral part of these financial statements. 22 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 700,000 Flagship Credit Auto Trust 2013-1, 5.38%, 7/15/20 (144A) $ 704,798 205,051 Flagship Credit Auto Trust 2016-3, 1.61%, 12/15/19 (144A) 204,964 283,975 FNA 2015-1 Trust, 3.24%, 12/10/23 (144A) 282,237 100,000 Ford Credit Auto Owner Trust 2013-D, 1.54%, 3/15/19 99,967 553,000 2.88 Four Corners CLO II, Ltd., Floating Rate Note, 1/26/20 (144A) 551,093 364,373 Foursight Capital Automobile Receivables Trust 2016-1, 2.87%, 10/15/21 (144A) 365,038 4,462 1.26 Gale Force 3 CLO, Ltd., Floating Rate Note, 4/19/21 (144A) 4,458 118,210 GCAT 2015-1 LLC, 3.625%, 5/26/20 (Step) (144A) 118,257 86,739 GLC Trust 2013-1, 3.0%, 7/15/21 (144A) 85,611 465,158 GMAT 2013-1 Trust, 6.9669%, 8/25/53 (Step) 466,238 533,449 GMAT 2015-1 Trust, 4.25%, 9/25/20 (Step) (144A) 534,085 122,351 GO Financial Auto Securitization Trust 2015-2, 3.27%, 11/15/18 (144A) 122,492 200,000 Green Tree Agency Advance Funding Trust I, 3.0949%, 10/15/48 (144A) 200,016 500,000 Green Tree Agency Advance Funding Trust I, 4.0575%, 10/15/48 (144A) 496,425 493,566 1.21 GSAA Trust, Floating Rate Note, 6/25/35 468,274 60,102 1.53 GSAMP Trust 2005-HE1, Floating Rate Note, 12/25/34 59,796 9,352 1.07 GSAMP Trust 2006-SEA1, Floating Rate Note, 5/25/36 (144A) 9,345 175,255 2.13 GSRPM Mortgage Loan Trust 2003-2, Floating Rate Note, 6/25/33 170,214 102,931 1.08 GSRPM Mortgage Loan Trust 2006-1, Floating Rate Note, 3/25/35 (144A) 101,364 84,048 1.08 GSRPM Mortgage Loan Trust 2006-2, Floating Rate Note, 9/25/36 (144A) 83,158 290,307 Harley-Davidson Motorcycle Trust 2014-1, 1.1%, 9/15/19 290,121 200,000 Hero Residual Funding 2016-1R, 4.5%, 9/21/42 (144A) 202,040 47,500 HOA Funding LLC, 4.846%, 8/22/44 (144A) 42,174 10,815 0.95 Home Equity Asset Trust 2006-4, Floating Rate Note, 8/25/36 10,771 130,039 Home Equity Mortgage Trust, 5.821%, 4/25/35 (Step) 131,696 217,878 2.43 Home Equity Mortgage Trust, Floating Rate Note, 8/25/34 213,286 24,205 Home Loan Trust 2003-HI1, 5.77%, 4/25/28 (Step) 24,254 343,688 2.42 Home Partners of America 2016-1 Trust, Floating Rate Note, 3/17/33 (144A) 345,723 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 23 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 520,000 4.07 Home Partners of America 2016-1 Trust, Floating Rate Note, 3/18/33 (144A) $ 524,932 500,000 3.17 Home Partners of America 2016-2 Trust, Floating Rate Note, 10/17/33 (144A) 502,238 468,421 1.52 HomeBanc Mortgage Trust 2004-2, Floating Rate Note, 12/25/34 440,763 250,745 Honor Automobile Trust Securitization 2016-1A, 2.94%, 11/15/19 (144A) 251,052 500,000 Hyundai Auto Receivables Trust 2014-B, 2.1%, 11/15/19 501,192 470,944 1.64 Impac Secured Assets CMN Owner Trust, Floating Rate Note, 2/25/35 471,611 600,000 2.37 Invitation Homes 2014-SFR2 Trust, Floating Rate Note, 9/19/31 (144A) 600,615 355,000 Invitation Homes Trust 2014-SFR3 Class D, 3.51%, 12/17/31 354,999 170,301 2.28 Irwin Whole Loan Home Equity Trust 2003-C, Floating Rate Note, 6/25/28 168,613 117,256 3.78 Irwin Whole Loan Home Equity Trust 2003-C, Floating Rate Note, 6/25/28 116,479 34,275 5.28 Irwin Whole Loan Home Equity Trust 2003-D, Floating Rate Note, 11/25/28 34,258 357,665 1.48 Irwin Whole Loan Home Equity Trust 2005-B, Floating Rate Note, 12/25/29 354,488 1,638 1.46 IXIS Real Estate Capital Trust 2005-HE4, Floating Rate Note, 2/25/36 1,636 61,189 0.92 JP Morgan Mortgage Acquisition Trust 2006-ACC1, Floating Rate Note, 5/25/36 61,147 310,000 3.52 Kabbage Funding 2014-1 Resecuritization Trust, Floating Rate Note, 3/8/18 (144A) 309,758 300,000 Leaf Receivables Funding 11 LLC, 4.89%, 1/15/23 (144A) 297,236 256,022 1.22 Lehman ABS Manufactured Housing Contract Trust 2002-A, Floating Rate Note, 6/15/33 253,060 230,624 Marriott Vacation Club Owner Trust 2012-1, 3.5%, 5/20/30 (144A) 233,292 88,996 1.41 Morgan Stanley ABS Capital I, Inc. Trust 2005-NC2, Floating Rate Note, 3/25/35 88,869 392,148 MVW Owner Trust 2014-1, 2.7%, 9/22/31 (144A) 389,136 854,113 Nations Equipment Finance Funding II LLC, 3.276%, 1/22/19 (144A) 855,175 219,628 Nations Equipment Finance Funding III LLC, 3.61%, 2/22/21 (144A) 221,047 500,000 Navitas Equipment Receivables LLC 2015-1, 3.4%, 11/15/18 (144A) 504,117 600,000 Navitas Equipment Receivables LLC 2016-1, 5.05%, 12/15/21 (144A) 605,867 The accompanying notes are an integral part of these financial statements. 24 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 500,000 6.28 NCF Dealer Floorplan Master Trust, Floating Rate Note, 3/21/22 (144A) $ 490,170 334,713 1.48 New Century Home Equity Loan Trust 2005-1, Floating Rate Note, 3/25/35 333,265 73,384 4.38 New Century Home Equity Loan Trust, Floating Rate Note, 8/25/34 73,418 300,000 NextGear Floorplan Master Owner Trust, 2.61%, 10/15/19 (144A) 299,694 400,000 1.87 NextGear Floorplan Master Owner Trust, Floating Rate Note, 9/15/21 (144A) 400,363 560,000 2.35 NovaStar Mortgage Funding Trust Series 2004-3, Floating Rate Note, 12/25/34 534,110 644,372 2.42 NovaStar Mortgage Funding Trust Series 2004-4, Floating Rate Note, 3/25/35 640,893 130,774 1.42 NovaStar Mortgage Funding Trust Series 2005-2, Floating Rate Note, 10/25/35 130,333 168,355 NYCTL 2016-A Trust, 1.47%, 11/10/29 (144A) 167,183 500,000 Ocwen Master Advance Receivables Trust, 2.5207%, 8/17/48 (144A) 496,981 500,000 Ocwen Master Advance Receivables Trust, 3.704%, 11/15/47 (144A) 502,010 600,000 Oportun Funding III LLC, 3.69%, 7/8/21 (144A) 602,061 24,740 1.04 Option One Mortgage Loan Trust 2005-4 Asset-Backed Certificates Series 2005-4, Floating Rate Note, 11/25/35 24,721 115,881 Orange Lake Timeshare Trust 2012-A, 4.87%, 3/10/27 (144A) 117,974 451,778 OSAT 2016-NPL1 Trust, 3.75%, 7/25/56 (Step) (144A) 452,950 355,675 2.47 Oscar US Funding Trust IV, Floating Rate Note, 7/15/20 (144A) 355,860 569,431 1.90 Park Place Securities Inc Asset-Backed Pass-Through Certificates Series 2004-MHQ, Floating Rate Note, 12/25/34 567,779 124,866 1.15 Park Place Securities, Inc. Asset-Backed Pass-Through Certificates Series 2005-WHQ4, Floating Rate Note, 9/25/35 124,420 750,000 2.52 PFS Financing Corp., Floating Rate Note, 2/18/20 (144A) 755,121 387,522 Popular ABS Mortgage Pass-Through Trust 2004-4, 4.59504%, 9/25/34 (Step) 368,930 300,000 Prestige Auto Receivables Trust 2013-1, 3.04%, 7/15/20 (144A) 301,174 664,471 Pretium Mortgage Credit Partners I 2016-NPL1, 4.375%, 2/27/31 (Step) (144A) 670,122 332,002 Pretium Mortgage Credit Partners I 2016-NPL4 LLC, 4.0%, 7/25/31 (Step) (144A) 332,467 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 25 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 350,000 Progreso Receivables Funding IV LLC, 3.0%, 7/8/20 (144A) $ 349,995 500,000 3.27 Progress Residential 2016-SFR1 Trust, Floating Rate Note, 9/17/33 (144A) 506,431 110,584 Purchasing Power Funding 2015-A LLC, 3.5%, 12/15/19 (144A) 110,446 398,538 1.44 Quest Trust REMICS, Floating Rate Note, 3/25/34 (144A) 391,471 45,342 1.73 RAAC Series 2005-RP1 Trust, Floating Rate Note, 7/25/37 (144A) 45,207 141,653 1.03 RAAC Series 2006-RP2 Trust, Floating Rate Note, 2/25/37 (144A) 140,645 81,238 5.06 RAMP Series 2003-RS9 Trust, Floating Rate Note, 10/25/33 80,223 59,023 1.71 RAMP Series 2004-RS11 Trust, Floating Rate Note, 11/25/34 59,058 237,316 RBSHD 2013-1 Trust, 7.6853%, 10/25/47 (Step) (144A) 237,463 54,730 3.02 RFSC Series 2004-RP1 Trust, Floating Rate Note, 11/25/42 54,221 179,266 1.60 SASCO Mortgage Loan Trust 2005-GEL1, Floating Rate Note, 12/25/34 175,930 117,421 1.24 Saxon Asset Securities Trust 2005-3, Floating Rate Note, 11/25/35 116,704 30,020 1.01 Saxon Asset Securities Trust 2005-4, Floating Rate Note, 11/25/37 30,011 255,746 Sierra Auto Receivables Securitization Trust 2016-1, 2.85%, 1/18/22 (144A) 257,303 750,000 2.82 Silver Bay Realty 2014-1 Trust, Floating Rate Note, 9/18/31 (144A) 749,070 400,000 Skopos Auto Receivables Trust 2015-1, 5.43%, 12/15/23 (144A) 400,934 154,387 Skopos Auto Receivables Trust 2015-2, 3.55%, 2/17/20 (144A) 154,683 335,709 SNAAC Auto Receivables Trust 2013-1, 4.56%, 4/15/20 (144A) 336,148 300,000 Sofi Consumer Loan Program 2017-1 LLC, 3.28%, 1/26/26 (144A) 301,279 170,948 1.87 SoFi Professional Loan Program 2016-C LLC, Floating Rate Note, 10/25/36 (144A) 173,112 85,454 1.04 Soundview Home Loan Trust 2005-OPT4, Floating Rate Note, 12/25/35 84,644 730,927 1.08 Specialty Underwriting & Residential Finance Trust Series 2006-BC1, Floating Rate Note, 12/25/36 723,681 500,000 SPS Servicer Advance Receivables Trust Advance Receivables Backed Notes 2015-T3, 3.41%, 7/15/47 (144A) 502,288 The accompanying notes are an integral part of these financial statements. 26 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 300,000 SPS Servicer Advance Receivables Trust Advance Receivables Backed Notes 2016-T2, 3.1%, 11/15/49 (144A) $ 296,974 320,990 STORE Master Funding LLC, 5.77%, 8/20/42 (144A) 331,711 207,836 1.50 Structured Asset Investment Loan Trust 2005-6, Floating Rate Note, 7/25/35 207,399 136,729 Sunset Mortgage Loan Co 2014-NPL2 LLC, 3.721%, 11/16/44 (Step) (144A) 136,695 419,009 SVO 2012-A VOI Mortgage LLC, 2.0%, 9/20/29 (144A) 415,119 682,293 2.07 SWAY Residential 2014-1 Trust, Floating Rate Note, 1/20/32 (144A) 683,917 415,825 Tax Ease Funding LLC Series 16-1A, 3.13%, 6/15/28 413,036 60,789 Terwin Mortgage Trust Series TMTS 2005-14HE, 4.8492%, 8/25/36 (Step) 61,599 2,122 Tidewater Auto Receivables Trust 2016-A, 2.3%, 9/15/19 (144A) 2,122 700,000 1.72 Trafigura Securitisation Finance Plc. 2014-1, Floating Rate Note, 4/16/18 (144A) 698,713 500,000 United Auto Credit Securitization Trust 2016-1, 3.55%, 8/15/19 (144A) 503,157 400,000 United Auto Credit Securitization Trust 2016-2, 2.2%, 5/10/19 (144A) 399,889 1,000,000 VOLT LIV LLC, 3.5%, 2/25/47 (Step) (144A) 1,000,000 78,829 VOLT XIX LLC, 3.875%, 4/26/55 (Step) (144A) 78,983 437,392 VOLT XLVII LLC, 3.75%, 6/25/46 (Step) (144A) 437,262 741,211 VOLT XXV LLC, 3.5%, 6/26/45 (Step) (144A) 741,112 357,045 VOLT XXXIII LLC, 3.5%, 3/25/55 (Step) (144A) 357,713 819,111 VOLT XXXIX LLC, 4.125%, 10/25/45 (Step) (144A) 822,969 721,226 VOLT XXXV, 3.5%, 9/25/46 (Step) (144A) 718,112 359,211 VOLT XXXVI LLC, 3.625%, 7/25/45 (Step) (144A) 360,081 223,810 VOLT XXXVII LLC, 3.625%, 7/25/45 (Step) (144A) 223,838 714,654 VOLT XXXVIII LLC, 3.875%, 9/25/45 (Step) (144A) 716,413 600,000 Westlake Automobile Receivables Trust 2016-1, 3.29%, 9/15/21 (144A) 605,114 -------------- $ 60,517,382 -------------- Total Banks $ 60,517,382 ----------------------------------------------------------------------------------------------------- DIVERSIFIED FINANCIALS -- 1.3% Other Diversified Financial Services -- 0.7% 424,284 0.97 321 Henderson Receivables I LLC, Floating Rate Note, 6/15/41 (144A) $ 413,185 700,000 American Credit Acceptance Receivables Trust 2014-1, 5.2%, 4/12/21 (144A) 707,011 1,050,000 American Credit Acceptance Receivables Trust 2014-2, 4.96%, 5/10/21 (144A) 1,061,027 27,698 BCC Funding VIII LLC, 1.794%, 6/22/20 (144A) 27,698 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 27 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Other Diversified Financial Services -- (continued) 600,000 2.67 Colony American Homes 2014-2, Floating Rate Note, 7/19/31 (144A) $ 600,038 179,167 Diamond Resorts Owner Trust 2013-2, 2.62%, 5/20/26 (144A) 178,396 105,778 1.01 Mastr Asset Backed Securities Trust 2006-AB1 REMICS, Floating Rate Note, 2/25/36 105,534 149,262 1.08 Mastr Specialized Loan Trust, Floating Rate Note, 1/25/36 (144A) 146,752 271,324 PFS Tax Lien Trust 2014-1, 1.44%, 5/15/29 (144A) 269,536 182,701 Sierra Timeshare 2012-3 Receivables Funding LLC, 1.87%, 8/20/29 (144A) 181,643 68,674 Sierra Timeshare 2013-1 Receivables Funding LLC, 2.39%, 11/20/29 (144A) 68,555 56,169 Sierra Timeshare 2013-2 Receivables Funding LLC, 2.92%, 11/20/25 (144A) 56,118 126,379 Sierra Timeshare 2013-2 Receivables Funding LLC, 4.75%, 11/20/25 (144A) 124,078 119,234 TAL Advantage V LLC, 1.7%, 5/20/39 (144A) 118,087 -------------- $ 4,057,658 ----------------------------------------------------------------------------------------------------- Specialized Finance -- 0.0%+ 94,906 Alterna Funding I LLC, 1.639%, 2/15/21 (144A) $ 93,008 ----------------------------------------------------------------------------------------------------- Consumer Finance -- 0.6% 760,000 1.57 American Express Credit Account Secured Note Trust 2012-4, Floating Rate Note, 5/15/20 (144A) $ 761,697 500,000 AmeriCredit Automobile Receivables Trust 2012-4, 3.82%, 2/10/20 (144A) 501,156 550,000 AmeriCredit Automobile Receivables Trust 2013-4, 3.31%, 10/8/19 558,212 106,627 CPS Auto Receivables Trust 2013-A, 1.89%, 6/15/20 (144A) 106,593 30,466 CPS Auto Receivables Trust 2013-B, 1.82%, 9/15/20 (144A) 30,459 181,000 CPS Auto Receivables Trust 2014-C, 3.77%, 8/17/20 (144A) 181,603 1,000,000 Credit Acceptance Auto Loan Trust 2014-2, 2.67%, 9/15/22 (144A) 1,004,416 -------------- $ 3,144,136 ----------------------------------------------------------------------------------------------------- Investment Banking & Brokerage -- 0.0%+ 262,762 1.20 Chesapeake Funding LLC, Floating Rate Note, 3/9/26 (144A) $ 262,021 -------------- Total Diversified Financials $ 7,556,823 ----------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 28 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- UTILITIES -- 0.0%+ Independent Power Producers & Energy Traders -- 0.0%+ 30,441 Centerpoint Energy Transition Bond Co. II LLC, 5.17%, 8/1/19 $ 30,931 -------------- Total Utilities $ 30,931 ----------------------------------------------------------------------------------------------------- REAL ESTATE -- 0.1% Specialized REIT -- 0.1% 326,863 Hilton Grand Vacations Trust 2014-A, 2.07%, 11/25/26 (144A) $ 323,042 ----------------------------------------------------------------------------------------------------- Real Estate Services -- 0.0%+ 22,786 0.97 HSI Asset Securitization Corp. Trust 2006-OPT1, Floating Rate Note, 12/25/35 $ 22,696 -------------- Total Real Estate $ 345,738 ----------------------------------------------------------------------------------------------------- GOVERNMENT -- 0.0%+ Government -- 0.0%+ 156,135 1.07 FHLMC Structured Pass Through Securities, Floating Rate Note, 12/25/29 $ 152,843 -------------- Total Government $ 152,843 ----------------------------------------------------------------------------------------------------- TOTAL ASSET BACKED SECURITIES (Cost $71,679,364) $ 71,749,443 ----------------------------------------------------------------------------------------------------- COLLATERALIZED MORTGAGE OBLIGATIONS -- 28.8% ENERGY -- 0.1% Oil & Gas Exploration & Production -- 0.1% 300,000 2.47 Arbor Realty Commercial Real Estate Notes 2016-FL1, Ltd., Floating Rate Note, 9/15/26 (144A) $ 301,254 -------------- Total Energy $ 301,254 ----------------------------------------------------------------------------------------------------- CAPITAL GOODS -- 0.0%+ Construction & Engineering -- 0.0%+ 284,989 3.22 Velocity Commercial Capital Loan Trust 2016-1, Floating Rate Note, 4/25/46 (144A) $ 288,473 -------------- Total Capital Goods $ 288,473 ----------------------------------------------------------------------------------------------------- CONSUMER SERVICES -- 0.1% Hotels, Resorts & Cruise Lines -- 0.1% 309,319 Welk Resorts 2013-A LLC, 3.1%, 3/15/29 (144A) $ 309,253 -------------- Total Consumer Services $ 309,253 ----------------------------------------------------------------------------------------------------- BANKS -- 17.2% Diversified Banks -- 0.1% 700,708 5.89 CD 2007-CD5 Mortgage Trust REMICS, Floating Rate Note, 11/15/44 $ 707,407 ----------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- 17.1% 136,410 A10 Term Asset Financing 2013-2 LLC, 2.62%, 11/15/27 (144A) $ 136,031 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 29 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 154,097 1.34 Adjustable Rate Mortgage Trust 2005-5, Floating Rate Note, 9/25/35 $ 151,291 44,809 1.23 Alternative Loan Trust 2003-14T1, Floating Rate Note, 8/25/18 40,132 179,771 1.36 Alternative Loan Trust 2004-6CB, Floating Rate Note, 4/25/34 178,600 462,260 3.02 AMSR 2016-SFR1 Trust, Floating Rate Note, 11/17/33 (144A) 463,273 500,000 2.52 Arbor Realty Collateralized Loan Obligation 2015-FL1, Ltd., Floating Rate Note, 3/17/25 (144A) 493,498 800,000 2.97 BAMLL Commercial Mortgage Securities Trust 2014-FL1, Floating Rate Note, 12/17/31 (144A) 803,437 580,000 1.87 BAMLL Commercial Mortgage Securities Trust 2014-ICTS, Floating Rate Note, 6/15/28 (144A) 580,092 930,000 3.37 BAMLL Commercial Mortgage Securities Trust 2014-INLD REMICS, Floating Rate Note, 12/17/29 (144A) 942,330 775,000 3.30 BAMLL Commercial Mortgage Securities Trust 2014-INLD, Floating Rate Note, 12/17/29 (144A) 747,815 1,100,000 3.77 BAMLL Commercial Mortgage Securities Trust 2016-ASHF, Floating Rate Note, 3/15/28 (144A) 1,117,735 800,000 1.24 BAMLL Re-REMIC Trust 2014-FRR5, Floating Rate Note, 3/29/45 (144A) 786,651 486,096 3.03 BAMLL Re-REMIC Trust 2014-FRR7, Floating Rate Note, 10/26/44 (144A) 485,836 500,000 5.62 Banc of America Commercial Mortgage Trust 2006-1, Floating Rate Note, 9/10/45 499,445 573,985 6.20 Banc of America Commercial Mortgage Trust 2008-1, Floating Rate Note, 2/10/51 586,232 233,713 1.40 Banc of America Funding 2005-A Trust, Floating Rate Note, 2/20/35 227,897 1,442,414 Bayview Commercial Asset Trust 2007-2, 7/27/37 (Step) (144A) (c) 1 386,666 2.53 Bayview Opportunity Master Fund IVb Trust 2016-CRT1, Floating Rate Note, 10/27/27 (144A) 386,529 450,000 2.93 Bayview Opportunity Master Fund IVb Trust 2017-CRT1, Floating Rate Note, 10/25/28 (144A) 449,599 750,000 2.77 BBCMS Trust 2015-SLP, Floating Rate Note, 2/15/28 (144A) 741,326 143,668 3.42 BCAP LLC 2009-RR13-I Trust, Floating Rate Note, 9/26/35 (144A) 144,600 179,897 1.62 Bear Stearns ALT-A Trust 2004-11, Floating Rate Note, 11/25/34 175,954 560,245 1.48 Bear Stearns ALT-A Trust 2004-12, Floating Rate Note, 1/25/35 544,300 199,523 1.62 Bear Stearns ALT-A Trust 2004-12, Floating Rate Note, 1/25/35 189,317 The accompanying notes are an integral part of these financial statements. 30 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 618,250 1.62 Bear Stearns ALT-A Trust 2004-12, Floating Rate Note, 1/25/35 $ 587,691 73,049 1.52 Bear Stearns ALT-A Trust 2004-13, Floating Rate Note, 11/25/34 71,629 777,420 1.38 Bear Stearns ALT-A Trust 2004-4, Floating Rate Note, 6/25/34 766,124 127,587 1.28 Bear Stearns ALT-A Trust 2005-2, Floating Rate Note, 3/25/35 125,170 152,644 3.06 Bear Stearns ARM Trust 2003-3, Floating Rate Note, 5/25/33 152,275 56,861 3.32 Bear Stearns ARM Trust 2004-3, Floating Rate Note, 7/25/34 55,132 480,494 5.21 Bear Stearns Commercial Mortgage Securities Trust 2005-PWR7, Floating Rate Note, 2/11/41 479,935 745,051 5.70 Bear Stearns Commercial Mortgage Securities Trust 2007-PWR16 REMICS, Floating Rate Note, 6/11/40 745,168 59,971 3.35 Bear Stearns Mortgage Securities, Inc., Floating Rate Note, 6/25/30 60,782 900,000 2.73 BHMS 2014-ATLS Mortgage Trust REMICS, Floating Rate Note, 7/8/33 (144A) 885,696 1,610,000 2.12 BLCP Hotel Trust, Floating Rate Note, 8/15/29 (144A) 1,602,181 800,000 3.62 BXHTL 2015-JWRZ Mortgage Trust, Floating Rate Note, 5/15/29 (144A) 804,006 1,340,000 3.27 CDGJ Commercial Mortgage Trust 2014-BXCH, Floating Rate Note, 12/15/27 (144A) 1,334,550 149,389 Cendant Mortgage Corp., 6.25%, 3/25/32 (144A) 151,099 500,000 1.72 Cent CDO 14, Ltd., Floating Rate Note, 4/15/21 (144A) 469,142 963,306 Cent CLO, 2.52%, 8/1/24 (144A) 965,898 800,000 2.92 CFCRE 2015-RUM Mortgage Trust, Floating Rate Note, 7/15/30 (144A) 786,610 765,000 5.37 CFCRE 2015-RUM Mortgage Trust, Floating Rate Note, 7/15/30 (144A) 747,381 75,320 1.72 CG-CCRE Commercial Mortgage Trust 2014-FL1, Floating Rate Note, 6/16/31 (144A) 75,303 480,281 2.42 CGGS Commercial Mortgage Trust 2016-RND, Floating Rate Note, 2/15/33 (144A) 481,416 500,000 3.87 CGWF Commercial Mortgage Trust 2013-RKWH REMICS, Floating Rate Note, 11/15/30 (144A) 498,272 91,754 2.78 CHL Mortgage Pass-Through Trust 2004-14, Floating Rate Note, 8/25/34 88,403 39,172 Citicorp Mortgage Securities REMIC Pass-Through Certificates Trust Series 2005-4, 5.0%, 7/25/20 40,222 80,908 Citicorp Mortgage Securities REMIC Pass-Through Certificates Trust Series 2005-7, 5.0%, 10/25/35 81,344 396,692 6.04 Citigroup Commercial Mortgage Trust 2008-C7, Floating Rate Note, 12/10/49 402,356 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 31 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 300,000 4.07 Citigroup Commercial Mortgage Trust 2015-SHP2, Floating Rate Note, 7/15/27 (144A) $ 301,955 1,500,000 2.87 Citigroup Commercial Mortgage Trust 2015-SSHP REMICS, Floating Rate Note, 9/15/27 (144A) 1,476,559 148,219 Citigroup Mortgage Loan Trust 2010-4 REMICS, 5.0%, 10/25/35 (144A) 150,188 16,651 Citigroup Mortgage Loan Trust, Inc., 7.0%, 10/25/19 16,557 150,876 3.09 Citigroup Mortgage Loan Trust, Inc., Floating Rate Note, 2/25/35 109,993 400,000 Colony American Finance 2016-1, Ltd., 5.972%, 6/15/48 (Step) (144A) 409,529 216,196 2.73 Colony Mortgage Capital Series 2015-FL3, Ltd., Floating Rate Note, 9/5/32 (144A) 215,115 400,000 2.52 Colony Starwood Homes 2016-2 Trust, Floating Rate Note, 12/19/33 (144A) 401,281 349,155 2.72 COMM 2014-FL4 Mortgage Trust, Floating Rate Note, 7/15/31 (144A) 350,700 1,410,000 2.92 COMM 2014-FL5 Mortgage Trust, Floating Rate Note, 10/15/31 (144A) 1,401,766 400,000 1.57 COMM 2014-PAT Mortgage Trust REMICS, Floating Rate Note, 8/13/27 (144A) 400,125 820,000 2.36 COMM 2014-PAT Mortgage Trust, Floating Rate Note, 8/13/27 (144A) 805,208 1,850,000 2.37 COMM 2014-TWC Mortgage Trust, Floating Rate Note, 2/13/32 (144A) 1,852,892 500,000 3.42 Cosmopolitan Hotel Trust 2016-COSMO, Floating Rate Note, 11/15/33 (144A) 506,874 132,002 Credit Suisse First Boston Mortgage Securities Corp., 4.877%, 4/15/37 128,536 22,334 Credit Suisse First Boston Mortgage Securities Corp., 5.5%, 6/25/33 22,585 223,495 Credit Suisse First Boston Mortgage Securities Corp., 7.5%, 5/25/32 237,663 21,960 CSFB Mortgage-Backed Trust Series 2004-7, 5.25%, 10/25/19 22,210 400,000 3.02 CSMC 2015-TWNI Trust, Floating Rate Note, 3/15/28 (144A) 399,731 900,164 2.50 CSMC Series 2013-14R REMICS, Floating Rate Note, 10/27/37 (144A) 897,913 920,734 3.00 CSMC Trust 2014-OAK1, Floating Rate Note, 11/25/44 (144A) 918,687 900,000 2.62 CSMC Trust 2015-DEAL, Floating Rate Note, 4/16/29 (144A) 901,687 750,000 3.62 CSMC Trust 2015-SAND, Floating Rate Note, 8/15/30 (144A) 752,426 540,000 2.38 EQTY 2014-INNS Mortgage Trust REMICS, Floating Rate Note, 5/8/31 (144A) 538,356 The accompanying notes are an integral part of these financial statements. 32 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 1,020,000 1.98 EQTY 2014-INNS Mortgage Trust, Floating Rate Note, 5/8/31 (144A) $ 1,018,162 52,936 3.09 First Horizon Mortgage Pass-Through Trust 2004-AR1, Floating Rate Note, 2/25/34 52,311 645,091 3.00 FirstKey Mortgage Trust 2014-1 REMICS, Floating Rate Note, 11/25/44 (144A) 646,603 971,033 2.28 FORT CRE 2016-1 LLC, Floating Rate Note, 5/21/36 (144A) 971,033 500,000 2.13 Freddie Mac Structured Agency Credit Risk Debt Notes, Floating Rate Note, 8/25/29 501,097 397,766 Freddie Mac, 3.0%, 10/15/25 404,252 86,032 2.07 GAHR Commercial Mortgage Trust 2015-NRF, Floating Rate Note, 12/15/34 (144A) 86,370 750,000 2.42 Gale Force 3 Clo, Ltd., Floating Rate Note, 4/19/21 (144A) 735,439 139,423 Global Mortgage Securitization, Ltd., 5.25%, 4/25/32 (144A) 136,477 438,592 1.05 Global Mortgage Securitization, Ltd., Floating Rate Note, 4/25/32 (144A) 415,767 189,424 3.77 GMACM Mortgage Loan Trust 2004-AR1, Floating Rate Note, 6/25/34 188,492 1,000,000 2.07 GP Portfolio Trust 2014-GGP, Floating Rate Note, 2/15/27 (144A) 1,001,425 1,000,000 4.02 GS Mortgage Securities Corp Trust 2016-ICE2, Floating Rate Note, 2/15/33 (144A) 1,014,676 400,000 6.52 GS Mortgage Securities Corp Trust 2016-ICE2, Floating Rate Note, 2/15/33 (144A) 413,002 490,275 5.87 GS Mortgage Securities Trust 2007-GG10 REMICS, Floating Rate Note, 8/10/45 490,493 495,000 2.52 GS Mortgage Securities Trust 2014-GSFL, Floating Rate Note, 7/15/31 (144A) 490,061 217,489 1.56 GSAA Home Equity Trust 2004-6, Floating Rate Note, 6/25/34 212,533 250,000 3.22 Holmes Master Issuer Plc, Floating Rate Note, 10/15/54 (144A) 252,632 1,370,880 1.02 HomeBanc Mortgage Trust 2005-3, Floating Rate Note, 7/25/35 1,349,112 258,301 1.88 Homestar Mortgage Acceptance Corp. REMICS, Floating Rate Note, 9/25/34 253,169 1,091,078 1.42 Homestar Mortgage Acceptance Corp., Floating Rate Note, 3/25/34 1,044,237 150,922 1.48 Homestar Mortgage Acceptance Corp., Floating Rate Note, 6/25/34 148,401 109,077 1.68 Homestar Mortgage Acceptance Corp., Floating Rate Note, 7/25/34 107,941 433,491 1.40 Impac CMB Trust Series 2004-4, Floating Rate Note, 9/25/34 409,172 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 33 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 60,260 3.40 Impac CMB Trust Series 2004-8, Floating Rate Note, 8/25/34 $ 57,861 73,523 3.57 IndyMac INDX Mortgage Loan Trust 2004-AR6, Floating Rate Note, 10/25/34 70,617 250,000 4.02 Invitation Homes 2014-SFR1 Trust REMICS, Floating Rate Note, 6/17/31 (144A) 249,999 1,000,000 2.27 J.P. Morgan Chase Commercial Mortgage Securities Trust 2016-ASH, Floating Rate Note, 10/15/34 (144A) 1,004,689 500,000 2.87 J.P. Morgan Chase Commercial Mortgage Securities Trust 2016-WPT, Floating Rate Note, 10/15/33 (144A) 505,620 950,000 2.12 J.P. Morgan Chase Commercial Mortgage Securities Trust 2016-WSP, Floating Rate Note, 8/15/33 (144A) 949,721 69,007 4.84 JP Morgan Chase Commercial Mortgage Securities Trust 2004-LN2, Floating Rate Note, 7/15/41 (144A) 68,883 76,315 0.92 JP Morgan Chase Commercial Mortgage Securities Trust 2006-LDP9, Floating Rate Note, 5/15/47 75,823 500,205 5.79 JP Morgan Chase Commercial Mortgage Securities Trust 2007-CIBC20, Floating Rate Note, 2/12/51 505,568 829,224 5.88 JP Morgan Chase Commercial Mortgage Securities Trust 2007-LDP12, Floating Rate Note, 2/15/51 835,925 849,995 JP Morgan Chase Commercial Mortgage Securities Trust 2010-C2, 3.6159%, 11/15/43 (144A) 860,279 563,472 3.50 JP Morgan Chase Commercial Mortgage Securities Trust 2013-A5, Floating Rate Note, 7/25/20 570,713 1,670,000 2.02 JP Morgan Chase Commercial Mortgage Securities Trust 2014-BXH, Floating Rate Note, 4/15/27 (144A) 1,655,422 700,000 2.72 JP Morgan Chase Commercial Mortgage Securities Trust 2014-CBM, Floating Rate Note, 10/15/29 (144A) 696,486 270,000 2.97 JP Morgan Chase Commercial Mortgage Securities Trust 2014-FL4 REMICS, Floating Rate Note, 12/16/30 (144A) 267,432 144,152 2.52 JP Morgan Chase Commercial Mortgage Securities Trust 2014-FL4, Floating Rate Note, 12/16/30 (144A) 143,806 650,000 2.87 JP Morgan Chase Commercial Mortgage Securities Trust 2014-FL5 REMICS, Floating Rate Note, 7/15/31 (144A) 642,951 490,000 2.12 JP Morgan Chase Commercial Mortgage Securities Trust 2014-FL5, Floating Rate Note, 7/15/31 (144A) 492,155 948,324 2.17 JP Morgan Chase Commercial Mortgage Securities Trust 2014-FL6, Floating Rate Note, 11/17/31 (144A) 949,511 900,000 1.69 JP Morgan Chase Commercial Mortgage Securities Trust 2014-INN, Floating Rate Note, 6/15/29 (144A) 900,846 650,000 2.47 JP Morgan Chase Commercial Mortgage Securities Trust 2014-INN, Floating Rate Note, 6/15/29 (144A) 649,999 1,100,000 2.37 JP Morgan Chase Commercial Mortgage Securities Trust 2014-PHH, Floating Rate Note, 8/16/27 (144A) 1,099,979 143,455 2.02 JP Morgan Chase Commercial Mortgage Securities Trust 2015-FL7 REMICS, Floating Rate Note, 5/15/28 (144A) 143,213 The accompanying notes are an integral part of these financial statements. 34 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 850,000 2.57 JP Morgan Chase Commercial Mortgage Securities Trust 2015-FL7, Floating Rate Note, 5/15/28 (144A) $ 846,024 500,000 3.52 JP Morgan Chase Commercial Mortgage Securities Trust 2015-SGP, Floating Rate Note, 7/15/36 (144A) 504,377 70,352 JP Morgan Mortgage Trust 2004-S1, 5.0%, 9/25/34 72,013 1,022,343 1.28 JP Morgan Seasoned Mortgage Trust 2014-1, Floating Rate Note, 5/25/33 (144A) 969,933 451,656 4.00 La Hipotecaria Panamanian Mortgage Trust 2007-1, Floating Rate Note, 12/23/36 (144A) 439,800 268,321 5.86 LB-UBS Commercial Mortgage Trust 2007-C6, Floating Rate Note, 7/15/40 269,452 715,840 5.87 LB-UBS Commercial Mortgage Trust 2007-C7 REMICS, Floating Rate Note, 9/15/45 728,816 98,775 1.00 Lehman Brothers Small Balance Commercial Mortgage Trust 2006-1, Floating Rate Note, 4/25/31 (144A) 94,908 95,705 1.01 Lehman Brothers Small Balance Commercial Mortgage Trust 2006-1, Floating Rate Note, 4/25/31 (144A) 92,330 37,863 1.73 Lehman Brothers Small Balance Commercial Mortgage Trust 2007-3 Class 1A4, Floating Rate Note, 10/25/37 (144A) 37,390 60,002 1.83 Lehman Brothers Small Balance Commercial Mortgage Trust 2007-3, Floating Rate Note, 10/25/37 (144A) 59,679 1,520,946 2.77 LSTAR Commercial Mortgage Trust 2016-7, Floating Rate Note, 12/1/21 (144A) 1,505,737 1,299,784 2.77 LSTAR Securities Investment Trust 2016-5, Floating Rate Note, 11/1/21 (144A) 1,295,008 689,622 2.78 LSTAR Securities Investment, Ltd. 2015-7, Floating Rate Note, 7/1/17 (144A) 687,036 427,478 2.78 LSTAR Securities Investment, Ltd. 2015-8, Floating Rate Note, 8/3/20 (144A) 428,775 511,115 2.78 LSTAR Securities Investment, Ltd. 2016-1, Floating Rate Note, 1/1/21 (144A) 504,270 785,846 2.78 LSTAR Securities Investment, Ltd. 2016-2 REMICS, Floating Rate Note, 3/1/21 (144A) 782,530 959,663 2.77 LSTAR Securities Investment, Ltd. 2016-3, Floating Rate Note, 9/1/21 (144A) 950,666 1,340,457 2.77 LSTAR Securities Investment, Ltd. 2016-4, Floating Rate Note, 10/1/21 (144A) 1,331,091 1,461,846 2.78 LSTAR Securities Investment, Ltd. 2016-6, Floating Rate Note, 11/1/21 (144A) 1,444,872 1,291,816 2.78 LSTAR Securities Investment, Ltd. 2017-1, Floating Rate Note, 1/1/22 (144A) 1,277,313 1,000,000 2.77 LSTAR Securities Investment, Ltd. 2017-2, Floating Rate Note, 2/1/22 (144A) 987,632 102,942 1.13 MASTR Alternative Loan Trust 2005-1, Floating Rate Note, 2/25/35 102,133 20,367 1.18 MASTR Asset Securitization Trust 2003-6, Floating Rate Note, 7/25/18 19,956 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 35 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 440,334 1.52 Merrill Lynch Mortgage Investors Trust Series MLCC 2003-A, Floating Rate Note, 3/25/28 $ 417,864 174,592 2.18 Merrill Lynch Mortgage Investors Trust Series MLCC 2003-A, Floating Rate Note, 3/25/28 163,482 391,967 1.44 Merrill Lynch Mortgage Investors Trust Series MLCC 2003-C REMICS, Floating Rate Note, 6/25/28 373,170 442,176 2.02 Merrill Lynch Mortgage Investors Trust Series MLCC 2003-C, Floating Rate Note, 6/25/28 436,042 133,089 1.42 Merrill Lynch Mortgage Investors Trust Series MLCC 2003-G, Floating Rate Note, 1/25/29 127,449 31,135 2.67 Merrill Lynch Mortgage Investors Trust Series MLCC 2003-G, Floating Rate Note, 1/25/29 30,885 261,995 1.42 Merrill Lynch Mortgage Investors Trust Series MLCC 2003-H, Floating Rate Note, 1/25/29 257,411 391,927 1.34 Merrill Lynch Mortgage Investors Trust Series MLCC 2004-C, Floating Rate Note, 7/25/29 364,565 427,380 1.97 Merrill Lynch Mortgage Investors Trust Series MLCC 2004-E, Floating Rate Note, 11/25/29 412,999 452,277 1.34 Merrill Lynch Mortgage Investors Trust Series MLCC 2004-G, Floating Rate Note, 1/25/30 427,220 146,962 1.92 Merrill Lynch Mortgage Investors Trust Series MLCC 2004-G, Floating Rate Note, 1/25/30 141,989 296,352 1.24 Merrill Lynch Mortgage Investors Trust Series MLCC 2005-A, Floating Rate Note, 3/25/30 287,483 102,841 5.39 Merrill Lynch Mortgage Trust 2005-CKI1, Floating Rate Note, 11/12/37 102,765 885,465 5.83 Merrill Lynch Mortgage Trust 2007-C1, Floating Rate Note, 6/12/50 889,520 142,636 5.52 ML-CFC Commercial Mortgage Trust 2006-3, Floating Rate Note, 7/12/46 142,533 562,631 Morgan Stanley Capital I Trust 2007-HQ13, 5.569%, 12/15/44 570,356 488,417 5.57 Morgan Stanley Capital I Trust 2007-TOP25, Floating Rate Note, 11/12/49 487,551 500,000 2.97 Morgan Stanley Capital I Trust 2015-XLF1, Floating Rate Note, 8/14/31 (144A) 500,923 600,000 3.52 Morgan Stanley Capital I Trust 2015-XLF1, Floating Rate Note, 8/17/26 (144A) 599,973 500,000 2.12 Morgan Stanley Capital I Trust 2017-PRME, Floating Rate Note, 2/15/34 (144A) 496,792 463,744 1.32 Morgan Stanley Mortgage Loan Trust 2005-5AR, Floating Rate Note, 9/25/35 460,467 282,648 1.06 Morgan Stanley Mortgage Loan Trust 2005-6AR, Floating Rate Note, 11/25/35 277,021 31,927 1.05 Morgan Stanley Mortgage Loan Trust 2005-6AR, Floating Rate Note, 11/25/35 31,886 565,941 1.56 MortgageIT Trust 2004-1, Floating Rate Note, 11/25/34 552,854 The accompanying notes are an integral part of these financial statements. 36 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 216,330 0.92 Nomura Resecuritization Trust 2014-1R, Floating Rate Note, 10/26/36 (144A) $ 212,057 840,402 1.17 Opteum Mortgage Acceptance Corp Asset Backed Pass-Through Certificates 2005-4, Floating Rate Note, 11/25/35 798,762 500,000 3.14 Palmer Square Loan Funding 2016-2, Ltd., Floating Rate Note, 6/21/24 (144A) 499,984 138,094 2.22 PFP 2015-2, Ltd., Floating Rate Note, 7/14/34 (144A) 137,994 884,307 Pretium Mortgage Credit Partners I 2016-NPL5 LLC, 3.875%, 9/27/31 (Step) (144A) 884,915 400,000 2.52 Progress Residential 2016-SFR2 Trust, Floating Rate Note, 1/17/34 (144A) 400,439 307,047 RAAC Series 2004-SP2 Trust, 6.0%, 1/25/32 309,247 23,559 1.33 RALI Series 2002-QS16 Trust, Floating Rate Note, 10/25/17 23,452 9,058 RALI Series 2003-QS14 Trust, 5.0%, 7/25/18 9,078 468,192 1.38 RALI Series 2005-QA1 Trust, Floating Rate Note, 1/25/35 449,634 1,470 6.65 RAMP Series 2004-SL4 Trust, Floating Rate Note, 5/25/18 1,467 882,131 2.22 RESI Finance LP 2003-CB1, Floating Rate Note, 7/9/35 755,074 252,200 1.65 RESI MAC, 2014-1A, Floating Rate Note, 6/12/19 251,353 459,693 1.82 Resource Capital Corp 2014-CRE2, Ltd., Floating Rate Note, 4/15/32 (144A) 458,783 90,892 RREF 2015-LT7 LLC, 3.0%, 12/27/32 (144A) 90,892 128,685 2.65 Sequoia Mortgage Trust 2004-7, Floating Rate Note, 8/20/34 129,722 198,122 2.25 Sequoia Mortgage Trust 2013-8, Floating Rate Note, 6/25/43 189,864 101,453 3.00 Sequoia Mortgage Trust 2013-8, Floating Rate Note, 6/25/43 99,908 80,613 2.07 Sequoia Mortgage Trust, Floating Rate Note, 9/25/42 77,291 133,415 SilverLeaf Finance XVII LLC, 2.68%, 3/15/26 (144A) 132,222 145,000 2.69 Silverstone Master Issuer Plc, Floating Rate Note, 1/21/55 (144A) 145,489 254,299 1.68 Structured Asset Mortgage Investments Trust 2002-AR5, Floating Rate Note, 5/19/33 249,966 22,314 Structured Asset Securities Corp. Mortgage Loan Trust 2005-2XS, 4.65%, 2/25/35 (Step) 22,645 54,212 1.28 Structured Asset Securities Corp. Mortgage Pass-Through Certificates Series 2003-35, Floating Rate Note, 12/25/33 54,087 74,079 2.14 Thornburg Mortgage Securities Trust 2004-1, Floating Rate Note, 3/25/44 72,894 137,579 2.68 Thornburg Mortgage Securities Trust 2004-4, Floating Rate Note, 12/25/44 136,129 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 37 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 258,737 2.76 Velocity Commercial Capital Loan Trust 2014-1, Floating Rate Note, 9/25/44 (144A) $ 260,354 519,936 3.20 Velocity Commercial Capital Loan Trust 2015-1, Floating Rate Note, 6/25/45 (144A) 522,585 129,191 5.98 Wachovia Bank Commercial Mortgage Trust Series 2007-C33 REMICS, Floating Rate Note, 2/15/51 129,441 1,250,000 2.62 Wells Fargo Commercial Mortgage Trust 2014-TISH REMICS, Floating Rate Note, 2/15/27 (144A) 1,251,956 800,000 4.27 Wells Fargo Commercial Mortgage Trust 2014-TISH, Floating Rate Note, 1/15/27 (144A) 773,530 42,105 1.38 Wells Fargo Mortgage Backed Securities 2005-4 Trust, Floating Rate Note, 4/25/35 41,561 7,806 1.26 Westwood CDO II, Ltd., Floating Rate Note, 4/25/22 (144A) 7,798 -------------- $ 95,854,111 -------------- Total Banks $ 96,561,518 ----------------------------------------------------------------------------------------------------- DIVERSIFIED FINANCIALS -- 1.1% Other Diversified Financial Services -- 1.0% 750,000 5.63 Banc of America Commercial Mortgage Trust 2007-3, Floating Rate Note, 6/10/49 $ 751,529 358,324 5.64 Credit Suisse Commercial Mortgage Trust Series 2007-C3, Floating Rate Note, 6/15/39 359,150 671,180 5.94 Credit Suisse Commercial Mortgage Trust Series 2007-C4 REMICS, Floating Rate Note, 9/15/39 676,533 700,000 5.94 Credit Suisse Commercial Mortgage Trust Series 2007-C4, Floating Rate Note, 9/15/39 707,833 564,973 5.64 Morgan Stanley Capital I Trust 2007-TOP27 REMICS, Floating Rate Note, 6/11/42 566,833 957,255 6.29 Morgan Stanley Capital I Trust 2008-TOP29 REMICS, Floating Rate Note, 1/11/43 984,891 4,168 Rialto Capital Management LLC, 2.85%, 5/15/24 (144A) 4,161 943,300 2.86 Sequoia Mortgage Trust 2012-1, Floating Rate Note, 1/25/42 951,694 618,332 3.47 Sequoia Mortgage Trust 2012-1, Floating Rate Note, 1/25/42 630,654 -------------- $ 5,633,278 ----------------------------------------------------------------------------------------------------- Specialized Finance -- 0.1% 800,000 2.77 BAMLL Commercial Mortgage Securities Trust 2015-ASHF REMICS, Floating Rate Note, 1/15/28 (144A) $ 793,421 -------------- Total Diversified Financials $ 6,426,699 ----------------------------------------------------------------------------------------------------- GOVERNMENT -- 10.3% Government -- 10.3% 9,291 1.73 Collateralized Mortgage Obligation Trust 44, Floating Rate Note, 7/1/18 $ 9,313 The accompanying notes are an integral part of these financial statements. 38 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Government -- (continued) 359,720 2.78 Fannie Mae Connecticut Avenue Securities, Floating Rate Note, 10/25/23 $ 363,022 390,440 1.73 Fannie Mae Connecticut Avenue Securities, Floating Rate Note, 5/25/24 391,706 411,007 1.98 Fannie Mae Connecticut Avenue Securities, Floating Rate Note, 7/25/24 411,948 412,864 2.92 Fannie Mae Connecticut Avenue Securities, Floating Rate Note, 9/25/28 417,989 171,735 2.72 Fannie Mae Trust 2005-W4, Floating Rate Note, 6/26/45 183,494 450,069 1.04 Fannie Mae Whole Loan, Floating Rate Note, 11/25/46 450,898 159,549 Fannie Mae, 2.5%, 1/25/30 161,637 241,508 Fannie Mae, 2.5%, 11/25/25 245,029 116,381 Fannie Mae, 2.5%, 3/25/24 117,238 235,678 Fannie Mae, 2.5%, 6/25/24 238,275 226,190 Fannie Mae, 2.75%, 3/25/21 230,803 231,037 Fannie Mae, 3.0%, 1/25/29 233,524 234,748 Fannie Mae, 3.0%, 11/25/18 236,986 1,483,038 Fannie Mae, 3.0%, 6/25/22 1,509,831 49,468 Fannie Mae, 3.5%, 10/25/23 49,617 125,510 Fannie Mae, 3.5%, 6/25/21 128,070 399,132 Fannie Mae, 3.5%, 8/25/25 407,078 188,265 Fannie Mae, 4.0%, 10/25/24 192,781 624,489 Fannie Mae, 4.25%, 3/25/25 640,475 765,000 Fannie Mae, 4.5%, 4/25/24 799,759 76,209 Fannie Mae, 4.5%, 9/25/35 76,740 601,319 Fannie Mae, 5.0%, 3/25/24 627,498 1,466,512 1.23 Fannie Mae, Floating Rate Note, 11/25/32 1,468,478 140,014 Federal Home Loan Banks, 2.9%, 4/20/17 140,450 20,389 Federal Home Loan Mortgage Corp. REMICS, 3.5%, 10/15/18 20,620 40,358 1.07 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 1/15/36 40,271 480,860 1.07 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 1/15/37 478,567 17,284 0.97 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 10/15/20 17,323 151,118 1.35 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 10/15/37 152,225 124,748 1.12 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 11/15/36 124,565 60,589 1.12 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 11/15/36 60,480 279,442 1.14 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 11/15/37 278,787 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 39 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Government -- (continued) 49,504 1.17 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 12/15/32 $ 49,682 68,062 1.17 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 12/15/32 68,352 218,550 1.09 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 12/15/35 217,813 178,191 1.47 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 12/15/39 178,993 124,550 1.07 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 2/15/30 124,726 145,642 1.77 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 2/15/32 148,560 161,605 1.17 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 2/15/33 161,749 122,867 1.07 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 2/15/36 122,313 75,395 1.07 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 2/15/39 75,646 179,856 1.27 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 2/15/41 179,108 117,286 1.32 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 2/15/42 118,421 102,418 1.77 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 3/15/32 104,952 174,316 1.77 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 3/15/32 179,612 139,549 1.17 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 3/15/38 139,915 335,593 1.17 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 3/15/41 336,953 156,746 1.32 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 4/15/27 158,858 153,492 1.27 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 4/15/28 154,151 75,133 1.07 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 4/15/36 74,973 211,972 1.19 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 4/15/41 211,940 80,558 1.17 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 5/15/36 80,314 56,305 1.17 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 5/15/41 56,237 77,576 1.19 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 6/15/36 77,572 177,736 1.20 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 6/15/41 177,732 The accompanying notes are an integral part of these financial statements. 40 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Government -- (continued) 93,751 1.17 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 7/15/23 $ 94,183 142,255 1.27 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 7/15/36 142,706 27,007 1.37 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 8/15/18 27,099 154,329 1.02 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 8/15/25 154,577 72,410 0.97 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 8/15/26 72,425 55,240 1.02 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 8/15/35 54,984 129,198 1.02 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 8/15/36 128,350 134,200 1.07 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 9/15/26 134,495 49,065 1.22 Federal Home Loan Mortgage Corp. REMICS, Floating Rate Note, 9/15/33 49,069 253,075 Federal Home Loan Mortgage Corp., 2.75%, 11/15/25 257,051 215,484 Federal Home Loan Mortgage Corp., 3.0%, 1/15/30 221,097 384,623 Federal Home Loan Mortgage Corp., 3.0%, 12/15/24 388,064 49,992 Federal Home Loan Mortgage Corp., 3.5%, 8/15/28 51,021 97,277 Federal Home Loan Mortgage Corp., 4.0%, 1/15/34 98,825 1,009,662 1.27 Federal Home Loan Mortgage Corp., Floating Rate Note, 1/15/33 1,013,948 132,902 1.02 Federal Home Loan Mortgage Corp., Floating Rate Note, 1/15/35 132,250 49,607 1.09 Federal Home Loan Mortgage Corp., Floating Rate Note, 11/15/36 49,434 214,087 1.22 Federal Home Loan Mortgage Corp., Floating Rate Note, 2/17/32 215,953 210,294 1.12 Federal Home Loan Mortgage Corp., Floating Rate Note, 3/15/30 211,073 225,567 1.34 Federal Home Loan Mortgage Corp., Floating Rate Note, 3/15/32 226,604 734,210 1.08 Federal Home Loan Mortgage Corp., Floating Rate Note, 4/15/33 731,461 369,221 1.12 Federal Home Loan Mortgage Corp., Floating Rate Note, 4/15/36 368,449 19,361 0.92 Federal Home Loan Mortgage Corp., Floating Rate Note, 7/15/19 19,330 212,493 1.27 Federal Home Loan Mortgage Corp., Floating Rate Note, 7/15/28 214,847 388,338 1.27 Federal Home Loan Mortgage Corp., Floating Rate Note, 7/15/31 390,267 68,820 1.07 Federal Home Loan Mortgage Corp., Floating Rate Note, 8/15/19 68,738 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 41 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Government -- (continued) 681,505 3.78 Federal National Mortgage Association 2004-T2, Floating Rate Note, 7/25/43 $ 723,763 69,093 Federal National Mortgage Association REMICS, 1.5%, 11/25/20 69,038 149,032 Federal National Mortgage Association REMICS, 1.75%, 12/25/22 148,454 245,263 Federal National Mortgage Association REMICS, 3.0%, 1/25/21 248,910 66,663 Federal National Mortgage Association REMICS, 3.0%, 4/25/40 67,722 136,846 Federal National Mortgage Association REMICS, 3.5%, 10/25/39 139,413 64,786 Federal National Mortgage Association REMICS, 6.0%, 6/25/29 73,419 43,019 1.43 Federal National Mortgage Association REMICS, Floating Rate Note, 1/18/32 43,718 56,089 1.28 Federal National Mortgage Association REMICS, Floating Rate Note, 1/25/33 56,207 113,918 1.08 Federal National Mortgage Association REMICS, Floating Rate Note, 10/25/35 113,342 249,381 1.18 Federal National Mortgage Association REMICS, Floating Rate Note, 10/25/36 249,021 107,441 2.00 Federal National Mortgage Association REMICS, Floating Rate Note, 10/25/38 109,452 51,949 0.98 Federal National Mortgage Association REMICS, Floating Rate Note, 10/27/37 51,916 277,751 1.78 Federal National Mortgage Association REMICS, Floating Rate Note, 11/18/32 284,380 197,012 1.14 Federal National Mortgage Association REMICS, Floating Rate Note, 11/25/36 196,523 244,163 1.48 Federal National Mortgage Association REMICS, Floating Rate Note, 11/25/39 246,681 189,842 1.18 Federal National Mortgage Association REMICS, Floating Rate Note, 12/18/32 190,013 375,882 1.78 Federal National Mortgage Association REMICS, Floating Rate Note, 12/25/23 380,090 87,638 1.68 Federal National Mortgage Association REMICS, Floating Rate Note, 12/25/31 88,859 428,414 1.28 Federal National Mortgage Association REMICS, Floating Rate Note, 12/25/32 430,460 90,079 1.40 Federal National Mortgage Association REMICS, Floating Rate Note, 12/25/37 90,361 140,732 1.13 Federal National Mortgage Association REMICS, Floating Rate Note, 2/25/33 141,835 129,334 1.09 Federal National Mortgage Association REMICS, Floating Rate Note, 2/25/35 128,887 81,502 1.03 Federal National Mortgage Association REMICS, Floating Rate Note, 2/25/37 80,918 The accompanying notes are an integral part of these financial statements. 42 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Government -- (continued) 113,449 0.98 Federal National Mortgage Association REMICS, Floating Rate Note, 2/25/37 $ 112,457 4,816 1.23 Federal National Mortgage Association REMICS, Floating Rate Note, 2/25/38 4,818 100,495 1.28 Federal National Mortgage Association REMICS, Floating Rate Note, 3/25/24 101,615 214,678 1.18 Federal National Mortgage Association REMICS, Floating Rate Note, 3/25/34 214,744 124,461 1.18 Federal National Mortgage Association REMICS, Floating Rate Note, 3/25/34 124,535 93,171 1.13 Federal National Mortgage Association REMICS, Floating Rate Note, 3/25/35 93,527 822,825 1.08 Federal National Mortgage Association REMICS, Floating Rate Note, 3/25/36 818,488 158,288 1.03 Federal National Mortgage Association REMICS, Floating Rate Note, 3/25/37 157,151 111,405 1.14 Federal National Mortgage Association REMICS, Floating Rate Note, 3/25/37 111,957 77,574 1.03 Federal National Mortgage Association REMICS, Floating Rate Note, 3/25/37 77,100 163,609 1.13 Federal National Mortgage Association REMICS, Floating Rate Note, 3/25/37 162,441 593,477 1.00 Federal National Mortgage Association REMICS, Floating Rate Note, 3/25/45 575,950 379,756 1.68 Federal National Mortgage Association REMICS, Floating Rate Note, 4/25/32 385,372 384,000 1.78 Federal National Mortgage Association REMICS, Floating Rate Note, 4/25/32 395,933 42,796 1.18 Federal National Mortgage Association REMICS, Floating Rate Note, 4/25/34 42,836 185,367 1.03 Federal National Mortgage Association REMICS, Floating Rate Note, 4/25/36 184,296 422,784 1.28 Federal National Mortgage Association REMICS, Floating Rate Note, 5/18/32 424,589 62,994 1.28 Federal National Mortgage Association REMICS, Floating Rate Note, 5/25/33 63,110 68,088 1.13 Federal National Mortgage Association REMICS, Floating Rate Note, 5/25/36 67,861 98,260 1.18 Federal National Mortgage Association REMICS, Floating Rate Note, 5/25/37 97,479 154,558 1.33 Federal National Mortgage Association REMICS, Floating Rate Note, 5/25/40 155,743 131,576 1.23 Federal National Mortgage Association REMICS, Floating Rate Note, 6/25/36 131,651 156,978 1.02 Federal National Mortgage Association REMICS, Floating Rate Note, 6/25/37 155,613 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 43 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Government -- (continued) 55,270 1.03 Federal National Mortgage Association REMICS, Floating Rate Note, 6/25/37 $ 54,864 174,254 1.03 Federal National Mortgage Association REMICS, Floating Rate Note, 6/25/37 172,968 41,665 1.28 Federal National Mortgage Association REMICS, Floating Rate Note, 6/25/38 41,857 73,761 1.18 Federal National Mortgage Association REMICS, Floating Rate Note, 7/25/34 73,797 110,795 1.08 Federal National Mortgage Association REMICS, Floating Rate Note, 7/25/35 110,296 267,799 1.03 Federal National Mortgage Association REMICS, Floating Rate Note, 7/25/35 266,741 203,950 1.68 Federal National Mortgage Association REMICS, Floating Rate Note, 7/25/38 207,897 396,858 1.08 Federal National Mortgage Association REMICS, Floating Rate Note, 8/25/40 399,013 307,498 1.28 Federal National Mortgage Association REMICS, Floating Rate Note, 9/25/33 308,167 100,384 1.13 Federal National Mortgage Association REMICS, Floating Rate Note, 9/25/36 100,067 63,081 1.35 Federal National Mortgage Association REMICS, Floating Rate Note, 9/25/36 63,216 185,124 1.35 Federal National Mortgage Association REMICS, Floating Rate Note, 9/25/37 187,545 202,409 1.36 Federal National Mortgage Association REMICS, Floating Rate Note, 9/25/37 204,984 49,485 1.35 Federal National Mortgage Association REMICS, Floating Rate Note, 9/25/37 50,100 47,186 1.33 Federal National Mortgage Association REMICS, Floating Rate Note, 9/25/39 47,545 131,657 Federal National Mortgage Association, 1.233%, 3/25/18 130,963 53,861 Federal National Mortgage Association, 2.5%, 4/25/36 54,417 116,744 Federal National Mortgage Association, 2.75%, 6/25/20 117,624 117,280 Federal National Mortgage Association, 3.0%, 6/25/39 118,231 5,779 Federal National Mortgage Association, 3.5%, 7/25/24 5,778 216,795 1.13 Federal National Mortgage Association, Floating Rate Note, 10/18/32 218,447 315,461 1.08 Federal National Mortgage Association, Floating Rate Note, 11/25/27 317,178 223,149 1.63 Federal National Mortgage Association, Floating Rate Note, 2/25/23 223,918 43,539 1.08 Federal National Mortgage Association, Floating Rate Note, 3/25/18 43,512 256,198 1.13 Federal National Mortgage Association, Floating Rate Note, 3/25/36 255,836 562,321 1.28 Federal National Mortgage Association, Floating Rate Note, 4/25/33 564,610 The accompanying notes are an integral part of these financial statements. 44 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Government -- (continued) 156,583 3.06 Federal National Mortgage Association, Floating Rate Note, 4/25/35 $ 162,166 354,053 1.28 Federal National Mortgage Association, Floating Rate Note, 6/25/32 358,163 476,950 1.18 Federal National Mortgage Association, Floating Rate Note, 6/25/36 476,410 229,995 1.08 Federal National Mortgage Association, Floating Rate Note, 8/25/35 228,866 58,461 2.22 Federal National Mortgage Association, Floating Rate Note, 9/25/22 58,407 1,104,173 Freddie Mac REMICS, 3.5%, 11/15/25 1,154,549 501,899 1.72 Freddie Mac REMICS, Floating Rate Note, 2/15/32 516,074 69,861 1.12 Freddie Mac Strips, Floating Rate Note, 12/15/36 69,622 171,485 1.07 Freddie Mac Strips, Floating Rate Note, 8/15/36 170,725 170,365 2.23 Freddie Mac Structured Agency Credit Risk Debt Notes, Floating Rate Note, 11/25/23 170,849 56,929 1.78 Freddie Mac Structured Agency Credit Risk Debt Notes, Floating Rate Note, 2/25/24 56,952 700,000 3.67 Freddie Mac Structured Agency Credit Risk Debt Notes, Floating Rate Note, 7/25/28 728,726 525,928 Freddie Mac, 1.4%, 7/15/23 514,808 138,826 Freddie Mac, 2.0%, 11/15/20 140,073 1,003,117 Freddie Mac, 2.0%, 2/15/25 1,015,020 153,380 Freddie Mac, 2.0%, 8/15/20 154,402 142,397 Freddie Mac, 2.0%, 8/15/20 143,462 362,360 Freddie Mac, 2.0%, 9/15/25 364,506 868,544 Freddie Mac, 2.5%, 5/15/25 885,396 397,173 Freddie Mac, 3.0%, 2/15/24 401,851 270,826 Freddie Mac, 3.0%, 2/15/25 273,417 89,745 Freddie Mac, 3.0%, 4/15/24 90,213 364,639 Freddie Mac, 3.0%, 5/15/29 371,230 856,595 Freddie Mac, 3.0%, 8/15/25 872,434 593,997 Freddie Mac, 3.1%, 2/15/25 601,597 369,585 Freddie Mac, 3.5%, 10/15/28 373,573 114,233 Freddie Mac, 3.5%, 11/15/28 117,116 283,585 Freddie Mac, 3.5%, 2/15/25 287,858 538,078 Freddie Mac, 3.5%, 3/15/25 557,676 273,462 Freddie Mac, 3.5%, 6/15/24 277,949 31,304 Freddie Mac, 4.0%, 5/15/37 31,399 40,081 Freddie Mac, 4.5%, 11/15/24 40,198 270,495 Freddie Mac, 4.5%, 2/15/20 278,126 148,393 Freddie Mac, 4.5%, 3/15/19 151,279 469,535 1.17 Freddie Mac, Floating Rate Note, 9/15/31 468,780 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 45 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Government -- (continued) 1,000,000 4.88 FREMF Mortgage Trust 2011-K703, Floating Rate Note, 7/25/44 (144A) $ 1,030,671 500,000 2.90 FREMF Mortgage Trust 2013-K502, Floating Rate Note, 3/27/45 (144A) 500,201 571,504 4.03 FREMF Mortgage Trust 2014-KF04 REMICS, Floating Rate Note, 6/25/21 (144A) 577,522 853,707 4.78 FREMF Mortgage Trust 2014-KF05 REMICS, Floating Rate Note, 9/25/21 (144A) 828,494 896,238 3.35 FREMF Mortgage Trust 2014-KS02 REMICS, Floating Rate Note, 8/25/23 (144A) 892,315 944,513 2.58 FREMF Mortgage Trust 2015-KLSF REMICS, Floating Rate Note, 11/25/22 (144A) 953,802 1,576,811 Government National Mortgage Association REMICS, 2.0%, 1/16/46 1,576,132 896,151 Government National Mortgage Association REMICS, 4.0%, 9/20/37 918,067 266,783 Government National Mortgage Association, 2.0%, 3/16/23 267,582 166,100 Government National Mortgage Association, 2.75%, 12/20/37 167,473 30,170 Government National Mortgage Association, 3.0%, 12/20/38 30,495 154,046 Government National Mortgage Association, 3.0%, 4/20/41 157,670 273,341 Government National Mortgage Association, 3.5%, 5/20/39 280,441 49,679 Government National Mortgage Association, 3.5%, 8/20/38 49,966 76,010 Government National Mortgage Association, 4.5%, 11/20/37 76,445 232,702 Government National Mortgage Association, 4.5%, 2/20/38 240,993 28,525 Government National Mortgage Association, 5.0%, 4/20/36 29,221 178,080 1.02 Government National Mortgage Association, Floating Rate Note, 1/16/35 177,147 453,729 1.32 Government National Mortgage Association, Floating Rate Note, 1/16/40 456,905 604,672 1.32 Government National Mortgage Association, Floating Rate Note, 12/16/26 613,301 174,476 1.03 Government National Mortgage Association, Floating Rate Note, 2/20/35 173,571 121,832 1.28 Government National Mortgage Association, Floating Rate Note, 2/20/38 122,338 181,448 1.07 Government National Mortgage Association, Floating Rate Note, 4/16/31 181,952 The accompanying notes are an integral part of these financial statements. 46 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Government -- (continued) 98,902 1.27 Government National Mortgage Association, Floating Rate Note, 4/16/32 $ 99,733 467,398 1.32 Government National Mortgage Association, Floating Rate Note, 4/16/32 473,463 495,416 1.07 Government National Mortgage Association, Floating Rate Note, 5/16/33 496,723 547,289 1.17 Government National Mortgage Association, Floating Rate Note, 6/16/32 551,569 313,969 1.08 Government National Mortgage Association, Floating Rate Note, 8/20/40 310,286 213,583 1.30 NCUA Guaranteed Notes Trust REMICS, Floating Rate Note, 3/9/21 213,226 42,729 1.27 Structured Asset Mortgage Investments II Trust 2005-F1 REMICS, Floating Rate Note, 8/26/35 42,510 -------------- $ 58,026,654 -------------- Total Government $ 58,026,654 ----------------------------------------------------------------------------------------------------- TOTAL COLLATERALIZED MORTGAGE OBLIGATIONS (Cost $162,555,287) $ 161,913,851 ----------------------------------------------------------------------------------------------------- CORPORATE BONDS -- 39.5% ENERGY -- 3.2% Oil & Gas Equipment & Services -- 0.4% 580,000 Halliburton Co., 6.15%, 9/15/19 $ 640,370 775,000 National Oilwell Varco, Inc., 1.35%, 12/1/17 772,409 550,000 Schlumberger Holdings Corp., 1.9%, 12/21/17 (144A) 552,350 585,000 Schlumberger Holdings Corp., 2.35%, 12/21/18 (144A) 589,743 -------------- $ 2,554,872 ----------------------------------------------------------------------------------------------------- Integrated Oil & Gas -- 1.1% 560,000 Chevron Corp., 1.991%, 3/3/20 $ 560,000 600,000 1.42 Chevron Corp., Floating Rate Note, 11/16/18 603,191 600,000 1.41 Chevron Corp., Floating Rate Note, 5/16/18 603,000 585,000 CNOOC Nexen Finance 2014 ULC, 1.625%, 4/30/17 584,921 1,000,000 ConocoPhillips Co., 1.05%, 12/15/17 997,052 1,000,000 1.54 Exxon Mobil Corp., Floating Rate Note, 2/28/18 1,006,056 585,000 1.46 Shell International Finance BV, Floating Rate Note, 11/10/18 588,490 500,000 1.20 Shell International Finance BV, Floating Rate Note, 9/12/19 503,046 600,000 Statoil ASA, 3.125%, 8/17/17 605,101 -------------- $ 6,050,857 ----------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 47 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Oil & Gas Exploration & Production -- 0.2% 600,000 Canadian Natural Resources, Ltd., 1.75%, 1/15/18 $ 600,295 570,000 Canadian Natural Resources, Ltd., 5.7%, 5/15/17 574,941 175,000 WPX Energy, Inc., 7.5%, 8/1/20 188,562 -------------- $ 1,363,798 ----------------------------------------------------------------------------------------------------- Oil & Gas Refining & Marketing -- 0.3% 500,000 GS Caltex Corp., 3.25%, 10/1/18 (144A) $ 508,125 750,000 Phillips 66, 2.95%, 5/1/17 752,015 200,000 Valero Energy Corp., 9.375%, 3/15/19 229,026 -------------- $ 1,489,166 ----------------------------------------------------------------------------------------------------- Oil & Gas Storage & Transportation -- 1.2% 500,000 Buckeye Partners LP, 6.05%, 1/15/18 $ 517,644 1,150,000 Energy Transfer Partners LP, 2.5%, 6/15/18 1,158,050 750,000 Enterprise Products Operating LLC, 1.65%, 5/7/18 748,435 500,000 Enterprise Products Operating LLC, 2.55%, 10/15/19 506,015 700,000 Kinder Morgan, Inc. Delaware, 2.0%, 12/1/17 701,393 750,000 Spectra Energy Capital LLC, 6.2%, 4/15/18 784,218 500,000 Tennessee Gas Pipeline Co LLC, 7.5%, 4/1/17 502,430 495,000 TransCanada PipeLines, Ltd., 1.625%, 11/9/17 495,306 875,000 TransCanada PipeLines, Ltd., 1.875%, 1/12/18 876,611 500,000 1.66 TransCanada PipeLines, Ltd., Floating Rate Note, 1/12/18 502,672 -------------- $ 6,792,774 -------------- Total Energy $ 18,251,467 ----------------------------------------------------------------------------------------------------- MATERIALS -- 0.2% Fertilizers & Agricultural Chemicals -- 0.2% 1,000,000 Monsanto Co., 1.15%, 6/30/17 $ 999,043 -------------- Total Materials $ 999,043 ----------------------------------------------------------------------------------------------------- CAPITAL GOODS -- 1.2% Aerospace & Defense -- 0.6% 500,000 Precision Castparts Corp., 1.25%, 1/15/18 $ 499,974 1,050,000 The Boeing Co., 0.95%, 5/15/18 1,046,981 575,000 United Technologies Corp., 1.5%, 11/1/19 572,226 500,000 United Technologies Corp., 1.778%, 5/4/18 (Step) 500,622 580,000 United Technologies Corp., 1.8%, 6/1/17 581,011 -------------- $ 3,200,814 ----------------------------------------------------------------------------------------------------- Industrial Conglomerates -- 0.1% 575,000 Honeywell International, Inc., 1.4%, 10/30/19 $ 571,304 ----------------------------------------------------------------------------------------------------- Industrial Machinery -- 0.0%+ 360,000 Stanley Black & Decker, Inc., 1.622%, 11/17/18 $ 359,237 ----------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 48 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Trading Companies & Distributors -- 0.5% 1,100,000 Aircastle, Ltd., 6.75%, 4/15/17 $ 1,105,500 750,000 Aviation Capital Group Corp., 2.875%, 9/17/18 (144A) 758,438 750,000 GATX Corp., 1.25%, 3/4/17 749,998 -------------- $ 2,613,936 -------------- Total Capital Goods $ 6,745,291 ----------------------------------------------------------------------------------------------------- TRANSPORTATION -- 0.2% Railroads -- 0.2% 535,000 Burlington Northern Santa Fe LLC, 5.75%, 3/15/18 $ 557,996 500,000 TTX Co., 2.25%, 2/1/19 (144A) 500,634 -------------- $ 1,058,630 -------------- Total Transportation $ 1,058,630 ----------------------------------------------------------------------------------------------------- AUTOMOBILES & COMPONENTS -- 2.5% Automobile Manufacturers -- 2.5% 575,000 Daimler Finance North America LLC, 1.75%, 10/30/19 (144A) $ 571,143 565,000 Daimler Finance North America LLC, 2.3%, 1/6/20 (144A) 566,675 750,000 1.30 Daimler Finance North America LLC, Floating Rate Note, 3/10/17 (144A) 750,052 617,000 1.37 Daimler Finance North America LLC, Floating Rate Note, 8/1/17 (144A) 617,824 500,000 Ford Motor Credit Co LLC, 2.681%, 1/9/20 505,378 700,000 Ford Motor Credit Co. LLC, 1.724%, 12/6/17 700,309 250,000 Ford Motor Credit Co. LLC, 2.375%, 1/16/18 251,507 1,000,000 Ford Motor Credit Co. LLC, 2.875%, 10/1/18 1,014,325 500,000 1.48 Ford Motor Credit Co. LLC, Floating Rate Note, 3/27/17 500,230 750,000 1.36 Ford Motor Credit Co. LLC, Floating Rate Note, 9/8/17 750,545 1,145,000 Nissan Motor Acceptance Corp., 1.55%, 9/13/19 (144A) 1,128,880 1,000,000 Nissan Motor Acceptance Corp., 2.65%, 9/26/18 (144A) 1,011,051 500,000 1.49 Nissan Motor Acceptance Corp., Floating Rate Note, 3/3/17 (144A) 500,000 575,000 1.48 Nissan Motor Acceptance Corp., Floating Rate Note, 9/13/19 (144A) 575,844 1,455,000 Toyota Motor Credit Corp., 1.125%, 5/16/17 1,455,349 600,000 Toyota Motor Credit Corp., 1.25%, 10/5/17 600,488 575,000 Toyota Motor Credit Corp., 1.55%, 10/18/19 571,603 300,000 Toyota Motor Credit Corp., 1.75%, 5/22/17 300,518 877,000 1.41 Toyota Motor Credit Corp., Floating Rate Note, 1/17/19 879,349 600,000 1.73 Toyota Motor Credit Corp., Floating Rate Note, 2/19/19 606,744 500,000 Volkswagen International Finance NV, 1.6%, 11/20/17 (144A) 499,452 -------------- $ 14,357,266 -------------- Total Automobiles & Components $ 14,357,266 ----------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 49 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- CONSUMER DURABLES & APPAREL -- 0.1% Homebuilding -- 0.1% 650,000 DR Horton, Inc., 4.0%, 2/15/20 $ 676,000 -------------- Total Consumer Durables & Apparel $ 676,000 ----------------------------------------------------------------------------------------------------- MEDIA -- 0.2% Broadcasting -- 0.2% 575,000 NBCUniversal Enterprise, Inc., 1.974%, 4/15/19 (144A) $ 576,907 580,000 1.56 NBCUniversal Enterprise, Inc., Floating Rate Note, 4/15/18 (144A) 584,489 -------------- $ 1,161,396 -------------- Total Media $ 1,161,396 ----------------------------------------------------------------------------------------------------- RETAILING -- 0.3% Home Improvement Retail -- 0.1% 750,000 1.33 The Home Depot, Inc., Floating Rate Note, 9/15/17 $ 751,724 ----------------------------------------------------------------------------------------------------- Automotive Retail -- 0.2% 625,000 AutoZone, Inc., 1.625%, 4/21/19 $ 620,324 500,000 Volkswagen Group of America Finance LLC, 1.65%, 5/22/18 (144A) 498,582 -------------- $ 1,118,906 -------------- Total Retailing $ 1,870,630 ----------------------------------------------------------------------------------------------------- FOOD & STAPLES RETAILING -- 0.2% Food Retail -- 0.1% 380,000 The Kroger Co., 1.5%, 9/30/19 $ 375,271 ----------------------------------------------------------------------------------------------------- Hypermarkets & Super Centers -- 0.1% 740,000 Costco Wholesale Corp., 1.125%, 12/15/17 $ 739,185 -------------- Total Food & Staples Retailing $ 1,114,456 ----------------------------------------------------------------------------------------------------- FOOD, BEVERAGE & TOBACCO -- 1.1% Brewers -- 0.3% 800,000 2.29 Anheuser-Busch InBev Finance, Inc., Floating Rate Note, 2/1/21 $ 823,610 585,000 Anheuser-Busch InBev Worldwide, Inc., 1.375%, 7/15/17 585,304 -------------- $ 1,408,914 ----------------------------------------------------------------------------------------------------- Packaged Foods & Meats -- 0.7% 575,000 Danone SA, 1.691%, 10/30/19 (144A) $ 567,526 580,000 Kraft Heinz Foods Co., 2.0%, 7/2/18 581,611 575,000 Mondelez International Holdings Netherlands BV, 1.625%, 10/28/19 (144A) 567,051 585,000 1.50 Mondelez International Holdings Netherlands BV, Floating Rate Note, 10/28/19 (144A) 587,169 575,000 Smithfield Foods, Inc., 2.7%, 1/31/20 (144A) 577,582 1,000,000 Wm Wrigley Jr Co., 2.0%, 10/20/17 (144A) 1,003,738 -------------- $ 3,884,677 ----------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 50 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Tobacco -- 0.1% 840,000 Reynolds American, Inc., 2.3%, 8/21/17 $ 843,331 -------------- Total Food, Beverage & Tobacco $ 6,136,922 ----------------------------------------------------------------------------------------------------- HOUSEHOLD & PERSONAL PRODUCTS -- 0.1% Household Products -- 0.1% 500,000 Reckitt Benckiser Treasury Services Plc, 2.125%, 9/21/18 (144A) $ 501,812 -------------- Total Household & Personal Products $ 501,812 ----------------------------------------------------------------------------------------------------- HEALTH CARE EQUIPMENT & SERVICES -- 1.2% Health Care Equipment -- 0.5% 1,024,000 Becton Dickinson and Co., 1.8%, 12/15/17 $ 1,026,276 500,000 Boston Scientific Corp., 2.65%, 10/1/18 506,306 1,270,000 1.65 Medtronic, Inc., Floating Rate Note, 3/15/20 1,291,925 -------------- $ 2,824,507 ----------------------------------------------------------------------------------------------------- Health Care Distributors -- 0.3% 1,765,000 McKesson Corp., 1.292%, 3/10/17 $ 1,765,109 ----------------------------------------------------------------------------------------------------- Managed Health Care -- 0.4% 600,000 Aetna, Inc., 1.7%, 6/7/18 $ 600,433 625,000 Coventry Health Care, Inc., 5.95%, 3/15/17 626,050 585,000 UnitedHealth Group, Inc., 1.4%, 12/15/17 585,431 295,000 UnitedHealth Group, Inc., 1.45%, 7/17/17 295,299 -------------- $ 2,107,213 -------------- Total Health Care Equipment & Services $ 6,696,829 ----------------------------------------------------------------------------------------------------- PHARMACEUTICALS, BIOTECHNOLOGY & LIFE SCIENCES -- 1.3% Biotechnology -- 0.6% 575,000 AbbVie, Inc., 2.0%, 11/6/18 $ 577,955 600,000 Amgen, Inc., 2.125%, 5/15/17 601,197 600,000 1.30 Amgen, Inc., Floating Rate Note, 5/22/17 600,358 607,000 1.52 Amgen, Inc., Floating Rate Note, 5/22/19 611,787 600,000 Celgene Corp., 2.125%, 8/15/18 603,143 750,000 Gilead Sciences, Inc., 1.85%, 9/4/18 753,837 -------------- $ 3,748,277 ----------------------------------------------------------------------------------------------------- Pharmaceuticals -- 0.5% 750,000 Bayer US Finance LLC, 1.5%, 10/6/17 (144A) $ 749,840 605,000 Perrigo Co Plc, 2.3%, 11/8/18 606,136 750,000 1.19 Pfizer, Inc., Floating Rate Note, 5/15/17 750,468 575,000 Shire Acquisitions Investments Ireland DAC, 1.9%, 9/23/19 570,571 -------------- $ 2,677,015 ----------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 51 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Life Sciences Tools & Services -- 0.2% 1,000,000 Thermo Fisher Scientific, Inc., 2.4%, 2/1/19 $ 1,009,969 -------------- Total Pharmaceuticals, Biotechnology & Life Sciences $ 7,435,261 ----------------------------------------------------------------------------------------------------- BANKS -- 10.4% Diversified Banks -- 7.5% 1,155,000 ABN AMRO Bank NV, 1.8%, 9/20/19 (144A) $ 1,143,216 570,000 ABN AMRO Bank NV, 2.1%, 1/18/19 (144A) 571,040 66,783 1.06 American Express Bank FSB, Floating Rate Note, 6/12/17 66,824 1,000,000 Bank of America Corp., 2.0%, 1/11/18 1,004,649 1,135,000 Bank of America Corp., 2.6%, 1/15/19 1,149,426 600,000 Bank of America Corp., 3.875%, 3/22/17 600,877 300,000 Bank of America Corp., 5.75%, 12/1/17 309,396 585,000 2.07 Bank of America Corp., Floating Rate Note, 3/22/18 589,808 408,000 1.54 Bank of America Corp., Floating Rate Note, 8/25/17 408,683 750,000 Bank of America NA, 1.75%, 6/5/18 752,460 470,000 1.13 Bank of Montreal, Floating Rate Note, 7/14/17 470,569 585,000 1.53 Bank of Montreal, Floating Rate Note, 7/18/19 587,372 625,000 Banque Federative du Credit Mutuel SA, 2.0%, 4/12/19 (144A) 622,254 575,000 BPCE SA, 1.625%, 1/26/18 574,260 600,000 Citigroup, Inc., 1.35%, 3/10/17 600,013 750,000 Citigroup, Inc., 1.8%, 2/5/18 752,064 600,000 Citigroup, Inc., 2.05%, 12/7/18 601,742 1,450,000 1.58 Citigroup, Inc., Floating Rate Note, 4/27/18 1,456,437 1,220,000 2.74 Citigroup, Inc., Floating Rate Note, 5/15/18 1,240,147 560,000 Citizens Bank NA, 2.25%, 3/2/20 559,940 600,000 Citizens Bank NA, 2.5%, 3/14/19 605,222 650,000 1.21 Commonwealth Bank of Australia, Floating Rate Note, 3/13/17 (144A) 650,111 750,000 1.11 Commonwealth Bank of Australia, Floating Rate Note, 9/8/17 (144A) 750,521 580,000 1.55 Cooperatieve Rabobank UA New York, Floating Rate Note, 8/9/19 580,984 500,000 1.39 Credit Agricole SA London, Floating Rate Note, 6/12/17 (144A) 500,452 575,000 1.42 Danske Bank AS, Floating Rate Note, 9/6/19 (144A) 575,036 575,000 Discover Bank, 2.0%, 2/21/18 576,781 1,725,000 Discover Bank, 2.6%, 11/13/18 1,744,148 585,000 HSBC USA, Inc., 1.7%, 3/5/18 585,502 750,000 1.16 HSBC USA, Inc., Floating Rate Note, 6/23/17 750,690 580,000 ING Bank NV, 2.0%, 11/26/18 (144A) 580,029 600,000 2.13 ING Bank NV, Floating Rate Note, 3/22/19 (144A) 607,358 The accompanying notes are an integral part of these financial statements. 52 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Diversified Banks -- (continued) 560,000 1.65 ING Bank NV, Floating Rate Note, 8/15/19 (144A) $ 560,391 1,150,000 1.94 JPMorgan Chase & Co., Floating Rate Note, 1/25/18 1,157,814 500,000 3.69 JPMorgan Chase & Co., Floating Rate Note, 2/25/21 501,400 585,000 1.31 JPMorgan Chase Bank NA, Floating Rate Note, 9/21/18 586,802 575,000 Nordea Bank AB, 1.625%, 9/30/19 (144A) 567,968 600,000 Nordea Bank AB, 3.125%, 3/20/17 (144A) 600,682 585,000 1.36 Nordea Bank AB, Floating Rate Note, 4/4/17 585,048 295,000 Royal Bank of Canada, 1.25%, 6/16/17 295,277 560,000 Royal Bank of Canada, 2.125%, 3/2/20 559,597 1,000,000 1.09 Royal Bank of Canada, Floating Rate Note, 6/16/17 1,000,429 580,000 1.37 Royal Bank of Canada, Floating Rate Note, 7/29/19 580,838 750,000 1.41 Santander UK Plc, Floating Rate Note, 9/29/17 749,774 570,000 1.53 Skandinaviska Enskilda Banken AB, Floating Rate Note, 9/13/19 (144A) 570,830 575,000 Sumitomo Mitsui Banking Corp., 1.762%, 10/19/18 573,128 565,000 1.56 Sumitomo Mitsui Banking Corp., Floating Rate Note, 1/11/19 565,763 565,000 1.46 Sumitomo Mitsui Banking Corp., Floating Rate Note, 1/16/18 566,642 560,000 Sumitomo Mitsui Trust Bank, Ltd., 2.05%, 3/6/19 (144A) 559,949 750,000 1.33 Svenska Handelsbanken AB, Floating Rate Note, 9/6/19 751,995 500,000 The Bank of Nova Scotia, 1.45%, 4/25/18 499,738 585,000 The Bank of Nova Scotia, 1.65%, 6/14/19 581,870 261,000 1.19 The Bank of Nova Scotia, Floating Rate Note, 4/11/17 261,124 305,000 The Bank of Tokyo-Mitsubishi UFJ, Ltd., 2.7%, 9/9/18 (144A) 308,057 500,000 1.26 The Bank of Tokyo-Mitsubishi UFJ, Ltd., Floating Rate Note, 3/10/17 (144A) 500,068 500,000 1.15 The Bank of Tokyo-Mitsubishi UFJ, Ltd., Floating Rate Note, 9/8/17 (144A) 499,990 500,000 1.31 The Huntington National Bank, Floating Rate Note, 4/24/17 500,189 500,000 The Toronto-Dominion Bank, 1.4%, 4/30/18 500,028 500,000 1.12 The Toronto-Dominion Bank, Floating Rate Note, 5/2/17 500,176 600,000 1.55 The Toronto-Dominion Bank, Floating Rate Note, 8/13/19 602,686 750,000 1.44 US Bancorp, Floating Rate Note, 4/25/19 752,050 600,000 Wells Fargo & Co., 1.15%, 6/2/17 599,981 600,000 Wells Fargo & Co., 5.625%, 12/11/17 619,094 575,000 1.51 Wells Fargo & Co., Floating Rate Note, 4/23/18 577,542 1,000,000 1.24 Westpac Banking Corp., Floating Rate Note, 5/19/17 1,000,869 -------------- $ 42,205,800 ----------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 53 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Regional Banks -- 2.9% 103,000 BB&T Corp., 1.6%, 8/15/17 $ 103,129 500,000 Branch Banking & Trust Co., 1.35%, 10/1/17 500,250 560,000 Branch Banking & Trust Co., 2.1%, 1/15/20 561,001 500,000 Branch Banking & Trust Co., 2.3%, 10/15/18 504,862 250,000 1.22 Branch Banking & Trust Co., Floating Rate Note, 5/23/17 250,080 500,000 Capital One NA, 1.85%, 9/13/19 496,710 550,000 Capital One NA, 2.35%, 1/31/20 551,263 750,000 Capital One NA, 2.35%, 8/17/18 755,160 485,000 Fifth Third Bank Cincinnati Ohio, 1.35%, 6/1/17 485,152 585,000 KeyBank NA Cleveland Ohio, 1.6%, 8/22/19 578,159 600,000 KeyBank NA Cleveland Ohio, 2.35%, 3/8/19 605,643 250,000 KeyCorp, 2.3%, 12/13/18 251,374 300,000 Manufacturers & Traders Trust Co., 1.45%, 3/7/18 299,818 1,000,000 1.18 Manufacturers & Traders Trust Co., Floating Rate Note, 7/25/17 1,001,500 1,000,000 MUFG Union Bank NA, 2.625%, 9/26/18 1,011,194 600,000 PNC Bank NA, 1.6%, 6/1/18 600,214 575,000 PNC Bank NA, 1.7%, 12/7/18 575,821 750,000 1.19 PNC Bank NA, Floating Rate Note, 8/1/17 750,692 560,000 SunTrust Bank, 2.25%, 1/31/20 562,001 750,000 1.29 The Toronto-Dominion Bank, Floating Rate Note, 7/2/19 752,767 565,000 US Bank NA Cincinnati Ohio, 2.0%, 1/24/20 566,414 1,450,000 1.62 US Bank NA Cincinnati Ohio, Floating Rate Note, 1/29/18 1,454,962 575,000 1.50 US Bank NA Cincinnati Ohio, Floating Rate Note, 8/23/17 575,826 1,077,000 1.12 Wachovia Corp., Floating Rate Note, 6/15/17 1,077,402 575,000 Wells Fargo Bank NA, 1.75%, 5/24/19 574,382 580,000 1.38 Wells Fargo Bank NA, Floating Rate Note, 9/7/17 581,146 -------------- $ 16,026,922 -------------- Total Banks $ 58,232,722 ----------------------------------------------------------------------------------------------------- DIVERSIFIED FINANCIALS -- 3.8% Other Diversified Financial Services -- 0.2% 600,000 General Electric Co., 2.3%, 4/27/17 $ 601,708 750,000 1.32 General Electric Co., Floating Rate Note, 5/15/17 750,409 -------------- $ 1,352,117 ----------------------------------------------------------------------------------------------------- Multi-Sector Holdings -- 0.4% 575,000 Berkshire Hathaway Finance Corp., 1.3%, 8/15/19 $ 569,422 580,000 Berkshire Hathaway Finance Corp., 1.6%, 5/15/17 580,891 1,000,000 1.16 Berkshire Hathaway Finance Corp., Floating Rate Note, 8/14/17 1,000,395 -------------- $ 2,150,708 ----------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 54 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Specialized Finance -- 0.4% 1,414,000 MassMutual Global Funding II, 1.55%, 10/11/19 (144A) $ 1,399,277 625,000 MassMutual Global Funding II, 2.0%, 4/5/17 (144A) 625,581 150,000 NYSE Holdings LLC, 2.0%, 10/5/17 150,633 -------------- $ 2,175,491 ----------------------------------------------------------------------------------------------------- Consumer Finance -- 1.5% 500,000 Ally Financial, Inc., 3.6%, 5/21/18 $ 508,750 600,000 American Express Credit Corp., 1.125%, 6/5/17 599,931 600,000 1.11 American Express Credit Corp., Floating Rate Note, 6/5/17 600,414 1,000,000 1.17 American Express Credit Corp., Floating Rate Note, 9/22/17 1,001,240 750,000 American Honda Finance Corp., 1.2%, 7/14/17 750,188 174,000 American Honda Finance Corp., 1.55%, 12/11/17 174,256 750,000 1.16 American Honda Finance Corp., Floating Rate Note, 12/11/17 751,448 580,000 1.45 American Honda Finance Corp., Floating Rate Note, 9/20/17 581,566 600,000 Capital One Bank USA NA, 1.3%, 6/5/17 600,018 750,000 Capital One NA, 1.65%, 2/5/18 750,776 625,000 General Motors Financial Co, Inc., 2.4%, 5/9/19 629,518 585,000 General Motors Financial Co, Inc., 3.1%, 1/15/19 595,631 429,000 2.34 General Motors Financial Co, Inc., Floating Rate Note, 5/9/19 435,821 485,000 1.03 PACCAR Financial Corp., Floating Rate Note, 6/6/17 485,210 -------------- $ 8,464,767 ----------------------------------------------------------------------------------------------------- Asset Management & Custody Banks -- 0.4% 550,000 1.95 State Street Corp., Floating Rate Note, 8/18/20 $ 559,989 750,000 The Bank of New York Mellon Corp., 1.969%, 6/20/17 (Step) 751,839 240,000 1.45 The Bank of New York Mellon Corp., Floating Rate Note, 8/1/18 240,692 587,000 1.59 The Goldman Sachs Group, Inc., Floating Rate Note, 5/22/17 587,824 -------------- $ 2,140,344 ----------------------------------------------------------------------------------------------------- Investment Banking & Brokerage -- 0.7% 580,000 Morgan Stanley, 2.45%, 2/1/19 $ 585,348 750,000 1.60 Morgan Stanley, Floating Rate Note, 1/5/18 753,078 275,000 3.10 Morgan Stanley, Floating Rate Note, 11/9/18 275,747 500,000 2.26 Morgan Stanley, Floating Rate Note, 2/1/19 508,746 650,000 North American Development Bank, 2.3%, 10/10/18 658,650 575,000 The Goldman Sachs Group, Inc., 2.9%, 7/19/18 583,827 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 55 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Investment Banking & Brokerage -- (continued) 650,000 2.09 The Goldman Sachs Group, Inc., Floating Rate Note, 4/30/18 $ 656,787 -------------- $ 4,022,183 ----------------------------------------------------------------------------------------------------- Diversified Capital Markets -- 0.2% 750,000 2.70 ICBCIL Finance Co, Ltd., Floating Rate Note, 11/13/18 (144A) $ 758,277 -------------- $ 758,277 -------------- Total Diversified Financials $ 21,063,887 ----------------------------------------------------------------------------------------------------- INSURANCE -- 8.3% Life & Health Insurance -- 0.9% 560,000 Jackson National Life Global Funding, 2.2%, 1/30/20 (144A) $ 559,140 575,000 Pricoa Global Funding I, 2.2%, 5/16/19 (144A) 577,957 750,000 Principal Life Global Funding II, 1.2%, 5/19/17 (144A) 750,147 565,000 Principal Life Global Funding II, 2.15%, 1/10/20 (144A) 565,661 1,400,000 1.43 Principal Life Global Funding II, Floating Rate Note, 12/1/17 (144A) 1,405,260 413,000 Protective Life Corp., 7.375%, 10/15/19 465,468 565,000 Prudential Financial, Inc., 5.375%, 6/21/20 618,828 -------------- $ 4,942,461 ----------------------------------------------------------------------------------------------------- Multi-line Insurance -- 1.2% 575,000 American International Group, Inc., 2.3%, 7/16/19 $ 578,012 500,000 Metropolitan Life Global Funding I, 1.55%, 9/13/19 (144A) 494,134 585,000 Metropolitan Life Global Funding I, 1.75%, 12/19/18 (144A) 585,058 900,000 1.26 Metropolitan Life Global Funding I, Floating Rate Note, 4/10/17 (144A) 900,508 1,150,000 New York Life Global Funding, 1.125%, 3/1/17 (144A) 1,150,000 750,000 New York Life Global Funding, 1.45%, 12/15/17 (144A) 750,038 585,000 New York Life Global Funding, 1.5%, 10/24/19 (144A) 578,683 750,000 1.13 New York Life Global Funding, Floating Rate Note, 12/15/17 (144A) 751,940 600,000 The Hartford Financial Services Group, Inc., 5.375%, 3/15/17 600,878 -------------- $ 6,389,251 ----------------------------------------------------------------------------------------------------- Property & Casualty Insurance -- 0.1% 550,000 CNA Financial Corp., 7.35%, 11/15/19 $ 621,886 ----------------------------------------------------------------------------------------------------- Reinsurance -- 6.1% 1,150,000 6.88 Alamo Re, Ltd., Floating Rate Note, 6/7/17 (Cat Bond) (144A) $ 1,156,440 350,000 6.11 Alamo Re, Ltd., Floating Rate Note, 6/7/18 (Cat Bond) (144A) 363,230 The accompanying notes are an integral part of these financial statements. 56 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Reinsurance -- (continued) 250,000 3.36 Aozora Re, Ltd., Floating Rate Note, 4/7/23 (Cat Bond) (144A) $ 255,075 100,000 Arlington Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 8/31/16 (f) (g) 4,860 150,000 Arlington Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 8/31/17 (f) (g) 165,495 500,000 4.19 Atlas IX Capital DAC, Floating Rate Note, 1/17/19 (Cat Bond) (144A) 507,550 300,000 Berwick 2016-1 Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 2/1/18 (f) (g) 38,010 300,000 Berwick 2017-1 Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 2/1/19 (f) (g) 304,260 250,000 14.11 Blue Halo Re, Ltd., Floating Rate Note, 6/21/19 (Cat Bond) (144A) 251,850 600,000 4.26 Bonanza RE, Ltd., Floating Rate Note, 12/31/19 (Cat Bond) (144A) 593,580 400,000 5.50 Caelus Re IV, Ltd., Floating Rate Note, 3/6/20 (Cat Bond) (144A) 420,960 750,000 7.06 Caelus Re, Ltd., Floating Rate Note, 4/7/17 (Cat Bond) (144A) 752,700 250,000 Carnosutie 2016-N,Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 11/30/20 (f) (g) 29,925 250,000 Carnosutie 2017,Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 11/30/21 (f) (g) 250,500 1,500,000 5.35 Citrus Re, Ltd., Floating Rate Note, 4/18/17 (Cat Bond) (144A) 1,504,650 1,400,000 4.48 Citrus Re, Ltd., Floating Rate Note, 4/24/17 (Cat Bond) (144A) 1,403,500 250,000 Cypress Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 7/10/17 (f) (g) 220,075 600,000 Denning 2016 Segregated Account (Artex), Variable Rate Notes, 7/7/17 (f) (g) 594,540 500,000 2.65 East Lane Re VI, Ltd., Floating Rate Note, 3/14/18 (Cat Bond) (144A) 501,650 594,000 Eden Re II,Variable Rate Notes, 3/22/21 (f) (g) 602,435 527 Eden Re II, Variable Rate Notes, 4/23/19 (f) (g) 6,455 3,400,000 7.97 Everglades Re, Ltd., Floating Rate Note, 4/28/17 (Cat Bond) (144A) 3,421,760 250,000 0.00 Galilei Re, Ltd., Floating Rate Note, 1/8/20 (Cat Bond) (144A) 250,175 350,000 0.00 Galilei Re, Ltd., Floating Rate Note, 1/8/20 (Cat Bond) (144A) 350,945 250,000 0.00 Galilei Re, Ltd., Floating Rate Note, 1/8/20 (Cat Bond) (144A) 249,425 250,000 0.00 Galilei Re, Ltd., Floating Rate Note, 1/8/21 (Cat Bond) (144A) 250,775 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 57 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Reinsurance -- (continued) 52,500 6.47 Gator Re, Ltd., Floating Rate Note, 1/9/20 (Cat Bond) (144A) $ 7,875 300,000 Gleneagles Segregated Account (Artex SAC Ltd), Variable Rate Notes, 11/30/20 (f) (g) 50,460 750,000 2.52 Golden State Re II, Ltd., Floating Rate Note, 1/8/19 (Cat Bond) (144A) 747,375 600,000 Gullane Segregated Account (Artex SAC Ltd.), Variable Rate Note 11/30/20 (f) (g) 25,140 550,000 Gullane Segregated Account (Artex SAC Ltd.), Variable Rate Note 11/30/21 (f) (g) 554,675 750,000 4.24 Kilimanjaro Re, Ltd., Floating Rate Note, 11/25/19 (Cat Bond) (144A) 760,425 250,000 6.75 Kilimanjaro Re, Ltd., Floating Rate Note, 12/6/19 (Cat Bond) (144A) 255,700 250,000 9.25 Kilimanjaro Re, Ltd., Floating Rate Note, 12/6/19 (Cat Bond) (144A) 260,525 650,000 5.24 Kilimanjaro Re, Ltd., Floating Rate Note, 4/30/18 (Cat Bond) (144A) 656,695 350,000 5.00 Kilimanjaro Re, Ltd., Floating Rate Note, 4/30/18 (Cat Bond) (144A) 352,660 350,000 Kingsbarns Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 5/15/17 (f) (g) 345,310 450,000 2.50 Kizuna Re II, Ltd., Floating Rate Note, 4/6/18 (Cat Bond) (144A) 450,855 250,000 Lahinch Re, Variable Rate Notes, 5/10/21 (f) (g) 4,450 300,000 0.00 Limestone Re, Ltd., Floating Rate Note, 8/31/21 (Cat Bond) 300,210 750,000 4.03 Long Point Re III, Ltd., Floating Rate Note, 5/23/18 (Cat Bond) (144A) 758,700 250,000 Lorenz Re, Ltd., Variable Rate Notes, 3/31/18 (f) (g) 1,450 600,000 Lorenz Re, Ltd., Variable Rate Notes, 3/31/19 (f) (g) 645,900 300,000 Madison Re. Variable Rate Notes, 3/31/19 (f) (g) 323,430 650,000 2.25 Merna Re V, Ltd., Floating Rate Note, 4/7/17 (Cat Bond) (144A) 649,675 550,000 3.07 Nakama Re, Ltd., Floating Rate Note, 10/13/21 (Cat Bond) (144A) 556,930 1,000,000 Pangaea Re, Series 2015-1, Principal at Risk Notes, 2/1/19 (f) (g) 4,500 1,000,000 Pangaea Re, Series 2015-2, Principal at Risk Notes, 11/30/19 (f) (g) 80,700 500,000 Pangaea Re, Series 2016-2, Principal at Risk Notes, 11/30/20 (f) (g) 566,250 500,000 Pangaea Re., Variable Rate Notes, 11/30/21 (f) (g) 508,550 800,000 Pangaea Re., Variable Rate Notes, 2/1/20 (f) (g) 111,200 850,000 6.50 Pelican Re, Ltd., Floating Rate Note, 5/15/17 (Cat Bond) (144A) 856,205 The accompanying notes are an integral part of these financial statements. 58 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Reinsurance -- (continued) 500,000 4.81 PennUnion Re, Ltd., Floating Rate Note, 12/7/18 (Cat Bond) (144A) $ 504,250 500,000 Pinehurst Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 1/16/18 (f) (g) 476,050 300,000 Port Rush RE, Variable Rate Notes, 6/15/17 (f) (g) 68,490 500,000 5.75 Queen Street X Re, Ltd., Floating Rate Note, 6/8/18 (Cat Bond) (144A) 501,700 250,000 6.15 Queen Street XI Re Dac, Floating Rate Note, 6/7/19 (Cat Bond) (144A) 253,325 250,000 9.75 Residential Reinsurance 2013, Ltd., Floating Rate Note, 6/6/17 (Cat Bond) (144A) 252,775 250,000 3.61 Residential Reinsurance 2014, Ltd., Floating Rate Note, 6/6/18 (Cat Bond) (144A) 251,350 500,000 0.00 Residential Reinsurance 2016, Ltd., Floating Rate Note, 12/6/23 (Cat Bond) (144A) 486,500 250,000 0.00 Resilience Re, Ltd., 1/12/18 (Cat Bond) 234,900 350,000 0.00 Resilience Re, Ltd., 4/7/17 (Cat Bond) 352,800 250,000 0.00 Resilience Re, Ltd., 6/12/17 (Cat Bond) 249,650 250,000 4.50 Resilience Re, Ltd., Floating Rate Note, 1/9/19 (Cat Bond) 250,000 250,000 3.30 Resilience Re, Ltd., Floating Rate Note, 1/9/19 (Cat Bond) 250,000 750,000 4.00 Sanders Re, Ltd., Floating Rate Note, 5/5/17 (Cat Bond) (144A) 749,925 750,000 4.21 Sanders Re, Ltd., Floating Rate Note, 5/5/17 (Cat Bond) (144A) 750,300 650,000 3.97 Sanders Re, Ltd., Floating Rate Note, 6/7/17 (Cat Bond) (144A) 651,040 250,000 Sector Re V, Ltd., 12/1/21 (144A) (f) (g) 253,200 300,000 Sector Re V, Ltd., 3/1/21 (f) (g) 337,470 1,185 Sector Re V, Ltd., Variable Rate Notes, 12/1/20 (144A) (f) (g) 54,099 1,250 Sector Re V, Ltd., Variable Rate Notes, 3/1/20 (144A) (f) (g) 28,318 500,000 Shenandoah 2017-1 Segregated Account (Artex), Variable Rate Notes, 7/7/17 (f) (g) 490,050 250,000 Silverton Re, Ltd., 9/18/19 (144A) (f) (g) 254,600 400,000 Silverton Re, Ltd., Variable Rate Notes, 9/18/17 (144A) (f) (g) 800 250,000 Silverton Re, Ltd., Variable Rate Notes, 9/18/18 (144A) (f) (g) 12,200 500,000 12.00 Skyline Re, Ltd., Floating Rate Note, 1/6/20 (Cat Bond) 498,125 300,000 St. Andrews Segregated Account (Artex SAC Ltd.), Variable Rate Notes, 2/1/19 (f) (g) 303,540 300,000 St. Andrews Segregated Account (Artex SAC Ltd.), Variance Rate Notes, 2/1/18 (f) (g) 42,180 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 59 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Reinsurance -- (continued) 250,000 5.50 Tradewynd Re, Ltd., Floating Rate Note, 1/8/18 (Cat Bond) (144A) $ 251,750 600,000 Versutus 2016, Class A-1, Variable Rate Notes, 11/30/20 (f) (g) 24,480 450,000 Versutus Ltd., Series 2017-A, Variable RateNotes, 11/30/2021 (f) (g) 453,465 500,000 2.01 Vitality Re V, Ltd., Floating Rate Note, 1/7/19 (Cat Bond) (144A) 498,700 250,000 2.83 Vitality Re VII, Ltd., Floating Rate Note, 1/7/20 (Cat Bond) (144A) 254,050 400,000 2.47 Vitality Re VII, Ltd., Floating Rate Note, 1/7/20 (Cat Bond) (144A) 403,400 -------------- $ 34,730,147 -------------- Total Insurance $ 46,683,745 ----------------------------------------------------------------------------------------------------- SOFTWARE & SERVICES -- 0.4% Systems Software -- 0.4% 875,000 Microsoft Corp., 1.1%, 8/8/19 $ 866,344 300,000 Oracle Corp., 2.25%, 10/8/19 304,350 500,000 Oracle Corp., 2.375%, 1/15/19 508,226 575,000 1.07 Oracle Corp., Floating Rate Note, 7/7/17 575,621 -------------- $ 2,254,541 -------------- Total Software & Services $ 2,254,541 ----------------------------------------------------------------------------------------------------- TECHNOLOGY HARDWARE & EQUIPMENT -- 0.3% Technology Hardware, Storage & Peripherals -- 0.3% 585,000 Apple, Inc., 1.7%, 2/22/19 $ 587,410 550,000 Apple, Inc., 1.9%, 2/7/20 551,210 650,000 1.74 Apple, Inc., Floating Rate Note, 2/22/19 659,888 -------------- $ 1,798,508 -------------- Total Technology Hardware & Equipment $ 1,798,508 ----------------------------------------------------------------------------------------------------- SEMICONDUCTORS & SEMICONDUCTOR EQUIPMENT -- 0.5% Semiconductors -- 0.5% 500,000 Altera Corp., 2.5%, 11/15/18 $ 508,170 570,000 Broadcom Corp., 2.375%, 1/15/20 (144A) 570,529 700,000 Intel Corp., 1.35%, 12/15/17 700,685 200,000 Micron Semiconductor Asia Pte, Ltd., 1.258%, 1/15/19 198,635 500,000 Texas Instruments, Inc., 0.875%, 3/12/17 499,998 575,000 TSMC Global, Ltd., 1.625%, 4/3/18 (144A) 573,454 -------------- $ 3,051,471 -------------- Total Semiconductors & Semiconductor Equipment $ 3,051,471 ----------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 60 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- TELECOMMUNICATION SERVICES -- 0.9% Integrated Telecommunication Services -- 0.9% 650,000 AT&T, Inc., 1.7%, 6/1/17 $ 650,658 600,000 1.85 AT&T, Inc., Floating Rate Note, 11/27/18 605,035 575,000 British Telecommunications Plc, 2.35%, 2/14/19 579,202 300,000 Deutsche Telekom International Finance BV, 1.5%, 9/19/19 (144A) 295,073 570,000 1.60 Deutsche Telekom International Finance BV, Floating Rate Note, 1/17/20 (144A) 571,311 1,000,000 GTP Acquisition Partners I LLC, 2.35%, 6/15/45 (144A) 991,530 575,000 Orange SA, 1.625%, 11/3/19 565,540 575,000 Verizon Communications, Inc., 1.375%, 8/15/19 567,168 -------------- $ 4,825,517 -------------- Total Telecommunication Services $ 4,825,517 ----------------------------------------------------------------------------------------------------- UTILITIES -- 2.4% Electric Utilities -- 1.6% 500,000 American Electric Power Co., Inc., 1.65%, 12/15/17 $ 500,898 215,000 Duke Energy Corp., 2.1%, 6/15/18 216,082 1,740,000 1.38 Duke Energy Corp., Floating Rate Note, 4/3/17 1,740,853 440,000 1.11 Duke Energy Progress LLC, Floating Rate Note, 11/20/17 440,605 411,000 1.04 Duke Energy Progress LLC, Floating Rate Note, 3/6/17 411,017 1,180,000 Exelon Corp., 1.55%, 6/9/17 1,180,290 560,000 Georgia Power Company, 2% 3/30/2 559,731 575,000 NextEra Energy Capital Holdings, Inc., 1.649%, 9/1/18 574,320 750,000 NextEra Energy Capital Holdings, Inc., 2.056%, 9/1/17 752,842 600,000 NextEra Energy Capital Holdings, Inc., 2.3%, 4/1/19 605,575 755,000 PECO Energy Co., 5.35%, 3/1/18 784,111 575,000 PPL Capital Funding, Inc., 1.9%, 6/1/18 575,113 660,000 Southern California Edison Co., 1.125%, 5/1/17 660,152 -------------- $ 9,001,589 ----------------------------------------------------------------------------------------------------- Gas Utilities -- 0.1% 600,000 DCP Midstream Operating LP, 2.5%, 12/1/17 $ 600,000 ----------------------------------------------------------------------------------------------------- Multi-Utilities -- 0.7% 1,021,000 Dominion Resources, Inc. Virginia, 1.25%, 3/15/17 $ 1,021,059 320,000 Dominion Resources, Inc. Virginia, 1.6%, 8/15/19 316,100 850,000 Dominion Resources, Inc. Virginia, 1.875%, 1/15/19 850,180 575,000 Dominion Resources, Inc. Virginia, 1.9%, 6/15/18 574,813 575,000 Sempra Energy, 2.3%, 4/1/17 575,522 500,000 Sempra Energy, 9.8%, 2/15/19 574,938 -------------- $ 3,912,612 -------------- Total Utilities $ 13,514,201 ----------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 61 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- REAL ESTATE -- 0.7% Office REIT -- 0.3% 575,000 Alexandria Real Estate Equities, Inc., 2.75%, 1/15/20 $ 577,459 585,000 Highwoods Realty LP, 5.85%, 3/15/17 585,863 575,000 Highwoods Realty LP, 7.5%, 4/15/18 609,787 -------------- $ 1,773,109 ----------------------------------------------------------------------------------------------------- Health Care REIT -- 0.1% 500,000 Welltower, Inc., 2.25%, 3/15/18 $ 502,417 ----------------------------------------------------------------------------------------------------- Specialized REIT -- 0.3% 550,000 Ventas Realty LP, 2.7%, 4/1/20 $ 554,921 1,070,000 Ventas Realty LP, 4.0%, 4/30/19 1,110,210 -------------- $ 1,665,131 -------------- Total Real Estate $ 3,940,657 ----------------------------------------------------------------------------------------------------- TOTAL CORPORATE BONDS (Cost $221,766,286) $ 222,370,252 ----------------------------------------------------------------------------------------------------- U.S. GOVERNMENT AND AGENCY OBLIGATIONS -- 10.4% 1,152,940 Fannie Mae, 2.0%, 11/1/23 $ 1,159,672 1,212,234 Fannie Mae, 2.5%, 3/1/28 1,229,274 242,291 Fannie Mae, 2.5%, 6/1/23 246,698 768,543 Fannie Mae, 3.0%, 10/1/27 793,178 997,568 Fannie Mae, 3.0%, 11/1/27 1,029,589 446,298 Fannie Mae, 3.0%, 5/1/21 459,403 235,494 Fannie Mae, 4.0%, 12/1/19 242,555 161,521 Fannie Mae, 4.5%, 1/1/41 173,985 299,888 Fannie Mae, 4.5%, 5/1/39 325,773 499,302 Fannie Mae, 4.5%, 5/1/39 542,280 392,376 Fannie Mae, 5.0%, 10/1/41 430,595 114,834 Fannie Mae, 5.0%, 11/1/20 121,783 33,521 Fannie Mae, 5.5%, 12/1/35 37,540 183,298 Fannie Mae, 5.5%, 8/1/37 205,814 251,399 Fannie Mae, 6.0%, 10/1/22 268,043 15,897 Fannie Mae, 6.0%, 2/1/34 17,985 18,129 Fannie Mae, 6.0%, 4/1/38 20,546 199,989 Fannie Mae, 6.5%, 4/1/29 231,290 4,523 Fannie Mae, 6.5%, 7/1/32 5,269 1,705 Fannie Mae, 6.5%, 8/1/17 1,714 10,943 Fannie Mae, 7.0%, 1/1/36 12,317 350 Fannie Mae, 7.0%, 7/1/17 350 43,095 3.33 Fannie Mae, Floating Rate Note, 1/1/25 43,865 73,969 2.66 Fannie Mae, Floating Rate Note, 10/1/29 75,268 289,816 2.82 Fannie Mae, Floating Rate Note, 10/1/36 291,735 The accompanying notes are an integral part of these financial statements. 62 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- U.S. GOVERNMENT AND AGENCY OBLIGATIONS -- (continued) 70,117 3.42 Fannie Mae, Floating Rate Note, 11/1/24 $ 72,787 1,354 2.74 Fannie Mae, Floating Rate Note, 11/1/25 1,418 27,999 2.01 Fannie Mae, Floating Rate Note, 11/1/40 27,853 44,139 2.90 Fannie Mae, Floating Rate Note, 12/1/28 45,968 132,515 4.30 Fannie Mae, Floating Rate Note, 12/1/36 139,073 1,663 3.32 Fannie Mae, Floating Rate Note, 2/1/27 1,674 576 4.23 Fannie Mae, Floating Rate Note, 2/1/33 606 2,777 3.09 Fannie Mae, Floating Rate Note, 4/1/28 2,800 2,463 3.06 Fannie Mae, Floating Rate Note, 4/1/29 2,521 33,415 3.04 Fannie Mae, Floating Rate Note, 7/1/36 35,571 563,109 2.43 Fannie Mae, Floating Rate Note, 7/1/45 574,758 605,000 0.77 Federal Farm Credit Banks, Floating Rate Note, 10/17/17 605,456 645,968 Federal Home Loan Mortgage Corp., 2.5%, 10/1/27 655,416 106,163 Federal Home Loan Mortgage Corp., 4.0%, 5/1/24 111,835 64,437 Federal Home Loan Mortgage Corp., 4.5%, 7/1/19 65,933 61,740 Federal Home Loan Mortgage Corp., 4.5%, 7/1/19 63,174 57,491 Federal Home Loan Mortgage Corp., 5.0%, 12/1/39 62,907 34,638 Federal Home Loan Mortgage Corp., 5.0%, 2/1/21 36,624 23,729 Federal Home Loan Mortgage Corp., 5.5%, 8/1/23 25,443 1,697 2.92 Federal Home Loan Mortgage Corp., Floating Rate Note, 1/1/28 1,780 117,111 3.16 Federal Home Loan Mortgage Corp., Floating Rate Note, 10/1/31 118,753 4,107 2.76 Federal Home Loan Mortgage Corp., Floating Rate Note, 11/1/31 4,328 238,053 3.53 Federal Home Loan Mortgage Corp., Floating Rate Note, 12/1/31 238,714 8,392 3.42 Federal Home Loan Mortgage Corp., Floating Rate Note, 4/1/25 8,620 1,860 3.01 Federal Home Loan Mortgage Corp., Floating Rate Note, 4/1/29 1,882 3,517 2.66 Federal Home Loan Mortgage Corp., Floating Rate Note, 5/1/25 3,520 826 2.88 Federal Home Loan Mortgage Corp., Floating Rate Note, 7/1/18 825 38,898 3.28 Federal Home Loan Mortgage Corp., Floating Rate Note, 8/1/31 40,383 1,200,052 Federal National Mortgage Association, 2.0%, 8/1/23 1,207,053 1,031,616 Federal National Mortgage Association, 2.5%, 9/1/22 1,050,335 423,530 Federal National Mortgage Association, 3.0%, 12/1/21 435,966 401,021 Federal National Mortgage Association, 4.0%, 1/1/20 413,032 486,100 Federal National Mortgage Association, 4.0%, 10/1/20 500,933 511,590 Federal National Mortgage Association, 4.0%, 3/1/21 527,694 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 63 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- U.S. GOVERNMENT AND AGENCY OBLIGATIONS -- (continued) 133,164 Federal National Mortgage Association, 4.0%, 8/1/19 $ 137,127 155,571 Government National Mortgage Association I, 5.0%, 8/15/19 164,340 92,497 Government National Mortgage Association I, 6.0%, 11/15/36 105,865 39,758 Government National Mortgage Association I, 6.0%, 12/15/31 45,114 21,712 Government National Mortgage Association I, 6.5%, 10/15/37 24,848 21,943 Government National Mortgage Association I, 6.5%, 5/15/31 25,599 6,896 Government National Mortgage Association I, 6.5%, 7/15/35 7,864 49,904 Government National Mortgage Association I, 7.5%, 10/15/36 57,313 155,820 Government National Mortgage Association II, 6.0%, 10/20/21 163,022 120,167 Government National Mortgage Association II, 6.0%, 11/20/22 127,212 118,152 Government National Mortgage Association II, 6.0%, 4/20/22 123,649 43,610 Government National Mortgage Association II, 6.0%, 8/20/19 44,811 500,000 U.S. Treasury Bonds, 8.125%, 8/15/21 634,336 1,975,000 U.S. Treasury Notes, 0.625%, 6/30/18 1,964,353 2,250,000 U.S. Treasury Notes, 0.75%, 9/30/18 2,237,432 650,000 U.S. Treasury Notes, 0.875%, 4/15/19 644,719 1,150,000 U.S. Treasury Notes, 1.0%, 3/15/19 1,144,429 1,410,000 U.S. Treasury Notes, 1.0%, 6/30/19 1,399,755 1,970,000 U.S. Treasury Notes, 1.125%, 1/31/19 1,966,923 1,405,000 U.S. Treasury Notes, 1.125%, 5/31/19 1,399,567 2,335,000 U.S. Treasury Notes, 1.125%, 7/31/21 2,264,859 4,100,000 U.S. Treasury Notes, 1.125%, 8/31/21 3,973,807 2,000,000 U.S. Treasury Notes, 1.25%, 11/30/18 2,003,046 550,000 U.S. Treasury Notes, 1.375%, 5/31/21 540,418 2,500,000 U.S. Treasury Notes, 1.5%, 12/31/18 2,514,160 1,945,000 U.S. Treasury Notes, 1.5%, 3/31/19 1,954,422 865,000 U.S. Treasury Notes, 1.625%, 11/30/20 862,905 2,760,000 U.S. Treasury Notes, 1.625%, 6/30/19 2,778,867 1,385,000 U.S. Treasury Notes, 1.625%, 7/31/19 1,394,198 1,415,000 U.S. Treasury Notes, 2.0%, 10/31/21 1,423,015 2,550,000 U.S. Treasury Notes, 2.0%, 8/31/21 2,566,634 565,000 U.S. Treasury Notes, 2.125%, 9/30/21 571,488 3,295,000 U.S. Treasury Notes, 2.25%, 7/31/21 3,353,048 The accompanying notes are an integral part of these financial statements. 64 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- U.S. GOVERNMENT AND AGENCY OBLIGATIONS -- (continued) 1,380,000 U.S. Treasury Notes, 2.625%, 1/31/18 $ 1,401,347 1,575,000 U.S. Treasury Notes, 2.75%, 12/31/17 1,599,487 1,865,000 U.S. Treasury Notes, 3.125%, 5/15/19 1,938,798 ----------------------------------------------------------------------------------------------------- TOTAL U.S. GOVERNMENT AND AGENCY OBLIGATIONS (Cost $58,981,275) $ 58,610,933 ----------------------------------------------------------------------------------------------------- MUNICIPAL BONDS -- 0.7% (e) Municipal Development -- 0.7% 1,480,000 0.62 County of Jackson Mississippi, Floating Rate Note, 6/1/23 $ 1,480,000 2,395,000 0.48 Mississippi Business Finance Corp., Floating Rate Note, 11/1/35 2,395,000 -------------- $ 3,875,000 ----------------------------------------------------------------------------------------------------- TOTAL MUNICIPAL BONDS (Cost $3,875,000) $ 3,875,000 ----------------------------------------------------------------------------------------------------- SENIOR FLOATING RATE LOAN INTERESTS -- 5.9%** MATERIALS -- 0.6% Commodity Chemicals -- 0.1% 440,863 4.50 Tronox Pigments Holland BV, New Term Loan, 3/19/20 $ 443,848 ----------------------------------------------------------------------------------------------------- Diversified Chemicals -- 0.1% 539,024 3.59 Huntsman International LLC, 2021 Term B Loan, 10/1/21 $ 543,067 ----------------------------------------------------------------------------------------------------- Specialty Chemicals -- 0.3% 1,097,820 5.00 MacDermid, Inc., Tranche B-4 Term Loan, 10/13/23 $ 1,112,160 291,136 4.50 MacDermid, Inc., Tranche B-5 Term Loan, 6/7/20 295,139 118,103 3.03 WR Grace & Co-Conn, U.S. Term Loan, 1/23/21 118,989 -------------- $ 1,526,288 ----------------------------------------------------------------------------------------------------- Construction Materials -- 0.1% 20,376 4.25 CeramTec Acquisition Corp., Initial Dollar Term B-2 Loan, 8/30/20 $ 20,452 53,302 4.25 CeramTec GmbH, Dollar Term B-3 Loan, 8/30/20 53,502 174,619 4.25 CeramTec GmbH, Initial Dollar Term B-1 Loan, 8/30/20 175,274 -------------- $ 249,228 ----------------------------------------------------------------------------------------------------- Metal & Glass Containers -- 0.0%+ 76,771 4.75 BWAY Holding Co., Initial Term Loan (2016), 8/14/23 $ 77,018 ----------------------------------------------------------------------------------------------------- Diversified Metals & Mining -- 0.0%+ 22,111 3.75 Fortescue Metals Group Ltd., Bank Loan, 6/30/19 $ 22,259 ----------------------------------------------------------------------------------------------------- Steel -- 0.0%+ 143,204 4.56 TMS International Corp., Term B Loan, 10/2/20 $ 143,920 ----------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 65 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Paper Products -- 0.0%+ 239,867 7.75 Appvion, Inc., Term Commitment, 6/28/19 $ 233,470 -------------- Total Materials $ 3,239,098 ----------------------------------------------------------------------------------------------------- CAPITAL GOODS -- 0.6% Aerospace & Defense -- 0.1% 341,726 3.53 DigitalGlobe, Inc., Term Loan, 12/22/23 $ 343,790 414,502 3.50 Wesco Aircraft Hardare Corp., Tranche B Term Loan (First Lien), 2/24/21 412,257 -------------- $ 756,047 ----------------------------------------------------------------------------------------------------- Building Products -- 0.1% 398,636 4.25 Unifrax Corp., New Term B Loan, 12/31/19 $ 398,387 ----------------------------------------------------------------------------------------------------- Electrical Components & Equipment -- 0.1% 390,741 3.27 Southwire Co., Term Loan, 1/31/21 $ 394,323 334,326 6.50 WireCo WorldGroup, Inc., Initial Term Loan (First Lien), 7/22/23 338,087 -------------- $ 732,410 ----------------------------------------------------------------------------------------------------- Industrial Conglomerates -- 0.1% 326,836 3.00 Milacron LLC, Term Loan (First Lien), 9/25/23 $ 328,879 ----------------------------------------------------------------------------------------------------- Construction & Farm Machinery & Heavy Trucks -- 0.1% 395,000 5.00 Navistar, Inc., Tranche B Term Loan, 8/7/20 $ 398,555 252,520 3.54 Terex Corp., U.S. Term Loan (2017), 1/31/24 254,098 -------------- $ 652,653 ----------------------------------------------------------------------------------------------------- Industrial Machinery -- 0.1% 493,694 5.03 NN, Inc., Tranche B Term Loan, 10/19/22 $ 498,940 ----------------------------------------------------------------------------------------------------- Trading Companies & Distributors -- 0.0%+ 45,413 3.78 WESCO Distribution, Inc., Tranche B-1 Loan, 12/12/19 $ 45,569 -------------- Total Capital Goods $ 3,412,885 ----------------------------------------------------------------------------------------------------- COMMERCIAL SERVICES & SUPPLIES -- 0.3% Environmental & Facilities Services -- 0.2% 938,697 5.00 Wheelabrator, Term B Loan, 10/15/21 $ 948,769 42,146 5.00 Wheelabrator, Term C Loan, 10/15/21 42,598 -------------- $ 991,367 ----------------------------------------------------------------------------------------------------- Office Services & Supplies -- 0.0%+ 174,126 3.28 West Corp., Refinanced Term B-12 Loan, 6/17/23 $ 175,024 ----------------------------------------------------------------------------------------------------- Security & Alarm Services -- 0.1% 469,379 4.00 Garda World Security Corp., Term B Loan, 11/1/20 $ 472,117 120,074 4.00 Garda World Security Corp., Term B Loan, 11/8/20 120,774 -------------- $ 592,891 ----------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 66 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Human Resource & Employment Services -- 0.0%+ 101,477 4.22 On Assignment, Inc., Tranche B-2 Term Loan, 6/5/22 $ 102,238 -------------- Total Commercial Services & Supplies $ 1,861,520 ----------------------------------------------------------------------------------------------------- TRANSPORTATION -- 0.2% Airlines -- 0.2% 735,000 3.27 American Airlines, Inc., 2015 Term Loan, 10/10/21 $ 739,640 96,970 3.27 Delta Air Lines, Inc., 2014 Term B-1 Loan, 10/18/18 97,848 -------------- $ 837,488 ----------------------------------------------------------------------------------------------------- Marine -- 0.0%+ 205,982 5.25 Navios Maritime Partners LP, Term Loan, 6/27/18 $ 205,724 -------------- Total Transportation $ 1,043,212 ----------------------------------------------------------------------------------------------------- AUTOMOBILES & COMPONENTS -- 0.3% Auto Parts & Equipment -- 0.2% 524,000 6.00 BBB Industries US, Initial Term Loan, 10/15/21 $ 527,432 460,528 3.75 MPG Holdco I, Inc., Tranche B-1 Term Loan (2015), 10/20/21 462,053 464,113 3.53 TI Group Automotive Systems LLC, Initial US Term Loan, 6/25/22 467,884 -------------- $ 1,457,369 ----------------------------------------------------------------------------------------------------- Automobile Manufacturers -- 0.1% 345,386 3.28 Chrysler Group LLC, Tranche B Term Loan, 12/29/18 $ 346,465 -------------- Total Automobiles & Components $ 1,803,834 ----------------------------------------------------------------------------------------------------- CONSUMER DURABLES & APPAREL -- 0.0%+ Housewares & Specialties -- 0.0%+ 210,000 3.50 Prestige Brands, Inc., Term B-4 Loan, 1/20/24 $ 212,888 -------------- Total Consumer Durables & Apparel $ 212,888 ----------------------------------------------------------------------------------------------------- CONSUMER SERVICES -- 0.4% Casinos & Gaming -- 0.1% 711,833 4.84 Scientific Games International, Inc., Initial Term B-3 Loan, 10/1/21 $ 722,866 ----------------------------------------------------------------------------------------------------- Hotels, Resorts & Cruise Lines -- 0.1% 21,499 3.50 Hilton Worldwide Finance LLC, Series B-1 Term Loan, 9/23/20 $ 21,690 292,300 3.28 Hilton Worldwide Finance LLC, Series B-2 Term Loan, 10/25/23 295,244 -------------- $ 316,934 ----------------------------------------------------------------------------------------------------- Education Services -- 0.2% 388,896 3.52 Bright Horizons Family Solutions, Term Loan (First Lien), 11/3/23 $ 393,855 734,887 4.55 Nord Anglia Education, Initial Term Loan, 3/31/21 744,532 -------------- $ 1,138,387 -------------- Total Consumer Services $ 2,178,187 ----------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 67 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- MEDIA -- 0.9% Broadcasting -- 0.5% 288,750 3.03 CBS Outdoor Americas Capital llc, Tranche B Term Loan (First Lien), 1/15/21 $ 290,134 310,077 4.51 Entercom Radio LLC, Term B Loan, 11/1/23 312,441 801,032 2.50 Gray Television, Inc., Term B-2 Loan, 2/7/24 808,642 194,458 3.54 Quebecor Media, Inc., Facility B-1 Tranche, 8/17/20 195,390 430,493 3.04 Sinclair Television Group, Inc., Tranche B Term Loan, 1/31/24 432,018 270,172 3.28 The EW Scripps Co., Tranche B Term Loan, 11/26/20 272,423 35,074 4.43 Tribune Media Co., Term B Loan, 12/27/20 35,128 438,249 3.78 Tribune Media Co., Term C Loan, 1/18/24 441,947 -------------- $ 2,788,123 ----------------------------------------------------------------------------------------------------- Cable & Satellite -- 0.3% 389,000 3.00 Mediacom Illinois LLC, Tranche K Term Loan, 2/19/24 $ 391,431 1,025,000 2.50 Ziggo Secured Finance Partnership, Term Loan (First Lien), 4/25/25 1,029,805 -------------- $ 1,421,236 ----------------------------------------------------------------------------------------------------- Movies & Entertainment -- 0.1% 241,913 3.52 AMC Entertainment, Inc., Initial Term Loan, 4/30/20 $ 244,735 498,750 3.31 Live Nation Entertainment, Inc., Term B-2 Loan, 10/27/23 505,296 -------------- $ 750,031 -------------- Total Media $ 4,959,390 ----------------------------------------------------------------------------------------------------- FOOD & STAPLES RETAILING -- 0.1% Food Retail -- 0.1% 451,553 4.30 Albertsons LLC, 2016-1 Term B-6 Loan, 6/23/23 $ 458,751 -------------- Total Food & Staples Retailing $ 458,751 ----------------------------------------------------------------------------------------------------- FOOD, BEVERAGE & TOBACCO -- 0.2% Agricultural Products -- 0.1% 510,563 3.28 Darling International, Inc., Term B USD Loan, 12/19/20 $ 517,902 ----------------------------------------------------------------------------------------------------- Packaged Foods & Meats -- 0.1% 477,086 3.25 JBS USA, Term Loan (First Lien), 10/30/22 $ 479,223 -------------- Total Food, Beverage & Tobacco $ 997,125 ----------------------------------------------------------------------------------------------------- HOUSEHOLD & PERSONAL PRODUCTS -- 0.1% Personal Products -- 0.1% 456,517 3.86 Party City Holdings, Inc., 2016 Replacement Term Loan, 8/19/22 $ 454,968 -------------- Total Household & Personal Products $ 454,968 ----------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 68 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- HEALTH CARE EQUIPMENT & SERVICES -- 0.6% Health Care Supplies -- 0.2% 260,788 3.53 Halyard Health, Inc., Term Loan, 11/1/21 $ 263,722 580,000 4.25 Kinetic Concepts, Inc., Term Loan B, 2/1/24 579,534 296,250 4.25 Sterigenics-Nordion Holdings LLC, Initial Term Loan, 4/27/22 296,802 -------------- $ 1,140,058 ----------------------------------------------------------------------------------------------------- Health Care Services -- 0.2% 496,250 4.00 Envision Healthcare Corp., Initial Term Loan, 11/17/23 $ 501,124 643,500 5.25 US Renal Care, Inc., Initial Term Loan (First Lien), 11/16/22 594,916 -------------- $ 1,096,040 ----------------------------------------------------------------------------------------------------- Health Care Facilities -- 0.1% 84,377 4.18 CHS, Incremental 2018 Term F Loan, 12/31/18 $ 84,248 88,816 3.75 CHS, Incremental 2019 Term G Loan, 12/31/19 88,233 163,419 4.00 CHS, Incremental 2021 Term H Loan, 1/27/21 160,917 269,474 4.31 Kindred Healthcare, Inc., Tranche B Loan (First Lien), 4/10/21 268,012 263,956 5.00 Vizient, Inc., Term B-2 Loan, 2/11/23 267,970 -------------- $ 869,380 ----------------------------------------------------------------------------------------------------- Health Care Technology -- 0.1% 391,000 3.75 Emdeon Inc., Term B-3 Loan, 2.50%, 11/2/18 $ 391,550 -------------- Total Health Care Equipment & Services $ 3,497,028 ----------------------------------------------------------------------------------------------------- PHARMACEUTICALS, BIOTECHNOLOGY & LIFE SCIENCES -- 0.2% Pharmaceuticals -- 0.2% 241,560 3.81 Endo Luxembourg Finance I Co Sarl, 2015 Incremental Term B Loan, 6/24/22 $ 242,818 274,407 3.75 Mallincrodt International Finance, Term Loan (First Lien), 9/24/24 275,951 466,284 5.53 Valeant Pharmaceuticals, Series F-1, 3/11/22 469,927 -------------- $ 988,696 -------------- Total Pharmaceuticals, Biotechnology & Life Sciences $ 988,696 ----------------------------------------------------------------------------------------------------- DIVERSIFIED FINANCIALS -- 0.3% Other Diversified Financial Services -- 0.2% 423,530 3.25 Delos Finance Sarl, Loan, 10/6/23 $ 427,765 335,000 3.79 Fly Funding II Sarl, Loan, 8/9/19 337,792 -------------- $ 765,557 ----------------------------------------------------------------------------------------------------- SPECIALIZED FINANCE -- 0.1% 523,259 3.25 101178 BC ULC, Term Loan (First Lien), 2/17/24 $ 524,370 195,000 3.04 SBA Senior Finance II LLC, Incremental Tranche B-1 Term Loan, 3/31/21 195,655 -------------- $ 720,025 ----------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 69 Schedule of Investments | 2/28/17 (unaudited) (continued) ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- Investment Banking & Brokerage -- 0.0%+ 143,340 4.28 LPL Holdings, Inc., 2021 Tranche B Term Loan, 3/29/21 $ 145,221 -------------- Total Diversified Financials $ 1,630,803 ----------------------------------------------------------------------------------------------------- SOFTWARE & SERVICES -- 0.2% Internet Software & Services -- 0.0%+ 185,786 3.27 Vantiv LLC, Term B Loan, 6/12/21 $ 187,760 ----------------------------------------------------------------------------------------------------- IT Consulting & Other Services -- 0.1% 394,939 3.25 CDW LLC, Term Loan, 8/16/23 $ 397,309 195,000 5.75 Evergreen Skills Lux Sarl, Initial Term Loan (First Lien), 4/23/21 178,974 -------------- $ 576,283 ----------------------------------------------------------------------------------------------------- Application Software -- 0.1% 345,941 4.79 MA FinanceCo LLC, Initial Tranche B-2 Term Loan, 11/20/21 $ 349,895 259,451 3.65 Verint Systems, Inc., Tranche B-2 Term Loan (First Lien), 9/6/19 261,267 -------------- $ 611,162 -------------- Total Software & Services $ 1,375,205 ----------------------------------------------------------------------------------------------------- TECHNOLOGY HARDWARE & EQUIPMENT -- 0.1% Communications Equipment -- 0.0%+ 277,516 3.28 Ciena Corporation, Term Loan (First Lien), 2/25/22 $ 279,250 ----------------------------------------------------------------------------------------------------- Electronic Equipment Manufacturers -- 0.1% 371,136 3.45 Zebra Technologies Corp., Refinancing Term Loan, 12/27/21 $ 376,096 -------------- Total Technology Hardware & Equipment $ 655,346 ----------------------------------------------------------------------------------------------------- SEMICONDUCTORS & SEMICONDUCTOR EQUIPMENT -- 0.1% Semiconductor Equipment -- 0.1% 606,038 3.25 Sensata Technologies BV, Sixth Amendment Term Loan, 10/14/21 $ 610,962 ----------------------------------------------------------------------------------------------------- Semiconductors -- 0.0%+ 199,500 4.03 On Semiconductor Corp., Term Loan (First Lien), 3/31/23 $ 201,855 -------------- Total Semiconductors & Semiconductor Equipment $ 812,817 ----------------------------------------------------------------------------------------------------- TELECOMMUNICATION SERVICES -- 0.2% Integrated Telecommunication Services -- 0.1% 225,000 3.03 Level 3 Financing, Term Loan (First Lien), 2/17/24 $ 226,434 368,342 4.22 GCI Holdings, Inc., New Term B Loan (2016), 2/2/22 370,875 -------------- $ 597,309 ----------------------------------------------------------------------------------------------------- Wireless Telecommunication Services -- 0.1% 235,662 3.52 Virgin Media Bristol LLC, I Facility, 1/31/25 $ 237,283 -------------- Total Telecommunication Services $ 834,592 ----------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 70 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ----------------------------------------------------------------------------------------------------- Floating Principal Rate (b) Amount ($) (unaudited) Value ----------------------------------------------------------------------------------------------------- UTILITIES -- 0.4% Electric Utilities -- 0.4% 912,797 6.00 APLP Holdings LP, Term Loan, 4/12/23 $ 921,925 654,708 3.28 Calpine Construction Finance Co. LP, Term B-2 Loan, 1/3/22 655,117 699,189 5.00 TPF II Power, LLC, Term Loan, 10/2/21 707,003 -------------- $ 2,284,045 -------------- Total Utilities $ 2,284,045 ----------------------------------------------------------------------------------------------------- REAL ESTATE -- 0.1% Hotel & Resort REIT -- 0.1% 312,638 3.28 MGM Growth Properties Operating Partnership LP, Term B Loan, 4/7/23 $ 315,102 -------------- Total Real Estate $ 315,102 ----------------------------------------------------------------------------------------------------- TOTAL SENIOR FLOATING RATE LOAN INTERESTS (Cost $32,658,830) $ 33,015,492 ----------------------------------------------------------------------------------------------------- TEMPORARY CASH INVESTMENTS -- 2.6% Commercial Paper -- 2.6% 500,000 Autozone Inc., Commercial Paper, 3/8/17 (d) $ 499,894 1,250,000 1.67 Bank of Montreal, Floating Rate Note, 3/16/18 1,249,669 500,000 1.46 Bank of Nova Scotia Houston, Floating Rate Note, 5/2/17 500,085 560,000 Bell Canada, Commercial Paper, 5/16/17 (d) 558,692 69,000 BMO Harris Bank NA, 1.0%, 4/24/17 69,041 560,000 Canadian National Resources, Commercial Paper, 3/28/17 (d) 559,504 320,000 1.30 Credit Agricole, Commercial Paper, 7/12/17 320,295 308,000 2.25 Credit Suisse AG New York NY, Floating Rate Note, 3/8/18 308,832 1,500,000 1.05 KBC Bank NV, Commercial Paper, 3/6/17 1,500,079 1,500,000 1.10 Mizuho Bank Limited, Commercial Paper, 5/5/17 1,500,701 600,000 1.72 Mizuho Bank, Ltd. New York, Floating Rate Note, 10/12/17 602,030 2,810,000 Natixis, Commercial Paper, 3/1/17 (d) 2,809,954 550,000 Oneok Partners, Commercial Paper, 3/1/17 (d) 549,986 345,000 1.56 Sumitomo Mitsui Trust Bank, Ltd., Floating Rate Note, 9/20/17 345,922 580,000 1.26 Sumitomo Mitsui, Floating Rate Note, 11/1/16 580,303 755,000 1.50 Sumitomo Mitsui, Floating Rate Note,7/20/17 756,039 540,000 1.36 Svenska Handelsbanken New York NY, Floating Rate Note, 5/26/17 540,084 750,000 0.93 UBS AG, Floating Rate Note, 5/25/17 751,111 550,000 Verizon Communications, Commercial Paper, 3/2/17 549,971 -------------- $ 14,552,192 ----------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 71 Schedule of Investments | 2/28/17 (unaudited) (continued) ------------------------------------------------------------------------------------------------------ Floating Principal Rate (b) Amount ($) (unaudited) Value ------------------------------------------------------------------------------------------------------ TOTAL TEMPORARY CASH INVESTMENTS (Cost $14,548,356) $ 14,552,192 ------------------------------------------------------------------------------------------------------ TOTAL INVESTMENT IN SECURITIES -- 100.7% (Cost $566,064,399) (a) $ 566,087,163 ------------------------------------------------------------------------------------------------------ OTHER ASSETS & LIABILITIES -- (0.7)% $ (4,042,975) ------------------------------------------------------------------------------------------------------ TOTAL NET ASSETS -- 100.0% $ 562,044,188 ====================================================================================================== + Amount rounds to less than 0.1%. (Cat Bond) Catastrophe or event-linked bond. At February 28, 2017, the value of these securities amounted to $26,492,635 or 4.7% of total net assets. See Notes to Financial Statements -- Note 1H. (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 February 28, 2017, the value of these securities amounted to $191,871,599 or 34.1% of total net assets. ARM Adjustable Rate Mortgage. REMICS Real Estate Mortgage Investment Conduits. REIT Real Estate Investment Trust. Strips Separate trading of Registered interest and principal of securities. ** 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) At February 28, 2017, the net unrealized depreciation on investments based on cost for federal income tax purposes of $567,234,747 was as follows: Aggregate gross unrealized appreciation for all investments in which there is an excess of value over tax cost $ 1,816,942 Aggregate gross unrealized depreciation for all investments in which there is an excess of tax cost over value (2,964,526) ------------ Net unrealized depreciation $(1,147,584) ============ (b) Debt obligation with a variable interest rate. Rate shown is rate at period end. (c) Security represents the interest only portion payments on a pool of underlying mortgages or mortgage-backed securities. (d) Security issued with a zero coupon. Income is earned through accretion of discount. (e) Consists of Revenue Bonds unless otherwise indicated. (f) Structured reinsurance investment. At February 28, 2017, the value of these securities amounted to $8,237,512 or 1.5% of total net assets. See Notes to Financial Statements -- Note 1H. (g) Rate to be determined. The accompanying notes are an integral part of these financial statements. 72 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 Purchases and sales of securities (excluding temporary cash investments) for the six months ended February 28, 2017 were as follows: -------------------------------------------------------------------------------- Purchases Sales -------------------------------------------------------------------------------- Long-Term U.S. Government $ 66,811,537 $ 62,502,831 Other Long-Term Securities 146,005,007 161,857,080 The Fund is permitted to engage in purchase and sale transactions ("cross trades") with certain Funds and accounts for which Pioneer Investment Management, Inc. (PIM) serves as the Fund's 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 February 28, 2017, the Fund engaged in purchases and sales pursuant to these procedures amounting to $6,275,116 and $15,658,165, respectively, which resulted in a net realized gain/loss of $(2,599). 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 February 28, 2017, in valuing the Fund's investments: ----------------------------------------------------------------------------------------------- Level 1 Level 2 Level 3 Total ----------------------------------------------------------------------------------------------- Asset Backed Securities $ -- $ 71,749,443 $ -- $ 71,749,443 Collateralized Mortgage Obligations -- 161,913,851 -- 161,913,851 Corporate Bonds Insurance Reinsurance -- 24,855,075 9,875,072 34,730,147 All Other Corporate Bonds -- 187,640,105 -- 187,640,105 U.S. Government Agency Obligations -- 58,610,933 -- 58,610,933 Municipal Bonds -- 3,875,000 -- 3,875,000 Senior Floating Rate Loan Interests -- 33,015,492 -- 33,015,492 Commercial paper -- 14,552,192 -- 14,552,192 ----------------------------------------------------------------------------------------------- Total $ -- $ 556,212,091 $ 9,875,072 $566,087,163 =============================================================================================== Other Financial Instruments Net unrealized appreciation on futures contracts $ 82,985 $ -- $ -- $ 82,985 ----------------------------------------------------------------------------------------------- Total Other Financial Instruments $ 82,985 $ -- $ -- $ 82,985 =============================================================================================== The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 73 Schedule of Investments | 2/28/17 (unaudited) (continued) The following is a reconciliation of assets valued using significant unobservable inputs (Level 3): -------------------------------------------------------------------------------- Corporate Bonds -------------------------------------------------------------------------------- Balance as of 8/31/16 $ 9,834,965 Realized gain (loss)(1) (3,524) Change in unrealized appreciation (depreciation)(2) 120,016 Purchases 5,167,760 Sales (5,244,145) Transfers in to Level 3* -- Transfers out of Level 3* -- -------------------------------------------------------------------------------- Balance as of 2/28/17 $ 9,875,072 ================================================================================ (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 February 28, 2017, there were no transfers between Levels 1, 2 and 3. Net change in unrealized appreciation (depreciation) of investments still held as of 2/28/17 $ 129,194 --------- The accompanying notes are an integral part of these financial statements. 74 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 Statement of Assets and Liabilities | 2/28/17 (unaudited) ASSETS: Investment in securities (cost $566,064,399) $ 566,087,163 Cash 3,363,616 Restricted cash* 513,001 Receivables -- Investment securities sold 349,230 Fund shares sold 2,955,494 Interest 1,777,413 Prepaid expenses 57,561 -------------------------------------------------------------------------------------------------- Total assets $ 575,103,478 -------------------------------------------------------------------------------------------------- LIABILITIES: Payables -- Investment securities purchased $ 10,506,007 Fund shares repurchased 2,036,396 Distributions 164,066 Variation margin for futures contracts 34,133 Trustee fees 4,148 Due to affiliates 31,619 Accrued expenses 282,921 -------------------------------------------------------------------------------------------------- Total liabilities $ 13,059,290 -------------------------------------------------------------------------------------------------- NET ASSETS: Paid-in capital $578,196,427 Undistributed net investment income (1,489,845) Accumulated net realized loss on investments (14,768,143) Net unrealized depreciation on investments 22,764 Unrealized depreciation on futures contracts 82,985 -------------------------------------------------------------------------------------------------- Total net assets $562,044,188 -------------------------------------------------------------------------------------------------- NET ASSET VALUE PER SHARE: (No par value, unlimited number of shares authorized) Class A (based on $172,704,717/18,125,424 shares) $ 9.53 Class C (based on $84,636,135/8,898,669 shares) $ 9.51 Class C2 (based on $2,788,301/293,073 shares) $ 9.51 Class K (based on $15,524,533/1,627,521 shares) $ 9.54 Class Y (based on $286,390,502/30,127,006 shares) $ 9.51 MAXIMUM OFFERING PRICE: Class A ($9.53 (divided by) 97.5%) $ 9.77 ================================================================================================== * Represents restricted cash deposited at the custodian and/or counterparty for derivative contracts. The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 75 Statement of Operations (unaudited) For the six months ended 2/28/17 INVESTMENT INCOME: Interest $6,861,458 --------------------------------------------------------------------------------------------------- Total investment income $ 6,861,458 --------------------------------------------------------------------------------------------------- EXPENSES: Management fees $ 994,484 Transfer agent fees Class A 115,795 Class C 30,448 Class C2 964 Class K 41 Class Y 181,828 Distribution fees Class A 176,821 Class C 228,062 Class C2 7,172 Shareholder communications expense 7,906 Administrative expense 104,524 Custodian fees 54,969 Registration fees 50,995 Professional fees 34,748 Printing expense 10,718 Fees and expenses of nonaffiliated Trustees 11,552 Miscellaneous 110,300 --------------------------------------------------------------------------------------------------- Total expenses $ 2,121,327 --------------------------------------------------------------------------------------------------- Net investment income $ 4,740,131 --------------------------------------------------------------------------------------------------- REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS AND FUTURES CONTRACTS Net realized gain (loss) on: Investments $ (266,176) Futures contracts (566,856) $ (833,032) --------------------------------------------------------------------------------------------------- Change in net unrealized appreciation (depreciation) on: Investments $ 641,659 Futures contracts 136,081 $ 777,740 --------------------------------------------------------------------------------------------------- Net realized and unrealized gain (loss) on investments and futures contracts $ (55,292) --------------------------------------------------------------------------------------------------- Net increase in net assets resulting from operations $ 4,684,839 =================================================================================================== The accompanying notes are an integral part of these financial statements. 76 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 Statements of Changes in Net Assets ----------------------------------------------------------------------------------------------------- Semi-Annual 2/28/17 Year Ended (unaudited) 8/31/16 ----------------------------------------------------------------------------------------------------- FROM OPERATIONS: Net investment income (loss) $ 4,740,131 $ 8,719,199 Net realized gain (loss) on investments (833,032) (1,065,864) Change in net unrealized appreciation (depreciation) on investments 777,740 1,792,249 ----------------------------------------------------------------------------------------------------- Net increase (decrease) in net assets resulting from operations $ 4,684,839 $ 9,445,584 ----------------------------------------------------------------------------------------------------- DISTRIBUTIONS TO SHAREOWNERS: Net investment income: Class A ($0.11 and $0.15 per share, respectively) $ (2,008,812) $ (3,226,254) Class C ($0.10 and $0.00 per share, respectively) (917,134) (1,384,199) Class C2 ($0.10 and $0.13 per share, respectively) (28,795) (44,578) Class K ($0.12 and $0.13 per share, respectively) (201,076) (277,479) Class Y ($0.12 and $0.18 per share, respectively) (3,509,789) (4,913,027) ----------------------------------------------------------------------------------------------------- Total distributions to shareowners $ (6,665,606) $ (9,845,537) ===================================================================================================== FROM FUND SHARE TRANSACTIONS: Net proceeds from sale or exchange of shares $ 122,678,323 $ 320,569,300 Reinvestment of distributions 5,513,014 8,167,268 Cost of shares repurchased (139,186,954) (350,725,882) ----------------------------------------------------------------------------------------------------- Net decrease in net assets resulting from Fund share transactions $ (10,995,617) $ (21,989,314) ----------------------------------------------------------------------------------------------------- Net decrease in net assets $ (12,976,384) $ (22,389,267) NET ASSETS: Beginning of year $ 575,020,572 $ 597,409,839 ----------------------------------------------------------------------------------------------------- End of year $ 562,044,188 $ 575,020,572 ----------------------------------------------------------------------------------------------------- Undistributed (distributions in excess of) net investment income $ (1,489,845) $ 435,630 ===================================================================================================== The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 77 Statements of Changes in Net Assets (continued) ------------------------------------------------------------------------------------------------ Semi-Annual Year Ended 2/28/17 2/28/17 Year Ended Year Ended Shares Amount 8/31/16 8/31/16 (unaudited) (unaudited) Shares Amount ------------------------------------------------------------------------------------------------ Class A Shares sold 2,836,129 $ 27,052,005 7,920,973 $ 75,411,797 Reinvestment of distributions 182,764 1,742,116 298,715 2,848,521 Less shares repurchased (3,703,828) (35,328,555) (10,872,579) (103,673,378) ------------------------------------------------------------------------------------------------ Net decrease (684,935) $ (6,534,434) (2,652,891) $ (25,413,060) ================================================================================================ Class C Shares sold 1,370,540 $ 13,041,057 5,709,801 $ 54,341,633 Reinvestment of distributions 93,495 889,639 140,618 1,338,300 Less shares repurchased (2,731,682) (26,016,408) (6,001,794) (57,127,721) ------------------------------------------------------------------------------------------------ Net decrease (1,267,647) $(12,085,712) (151,375) $ (1,447,788) ================================================================================================ Class C2 Shares sold 26,209 $ 249,665 161,411 $ 1,535,562 Reinvestment of distributions 1,299 12,363 1,951 18,584 Less shares repurchased (41,332) (394,275) (171,799) (1,636,013) ------------------------------------------------------------------------------------------------ Net decrease (13,824) $ (132,247) (8,437) $ (81,867) ================================================================================================ Class K Shares sold 98,610 $ 936,191 1,776,384 $ 16,995,201 Reinvestment of distributions 252 2,407 -- -- Less shares repurchased (195,359) (1,869,272) (287,286) (2,738,090) ------------------------------------------------------------------------------------------------ Net increase (decrease) (96,497) $ (930,674) 1,489,098 $ 14,257,111 ================================================================================================ Class Y Shares sold 8,556,832 $ 81,399,405 18,121,505 $ 172,285,107 Reinvestment of distributions 301,334 2,866,489 416,374 3,961,863 Less shares repurchased (7,942,454) (75,578,444) (19,487,306) (185,550,680) ------------------------------------------------------------------------------------------------ Net increase (decrease) 915,712 $ 8,687,450 (949,427) $ (9,303,710) ================================================================================================ The accompanying notes are an integral part of these financial statements. 78 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 Financial Highlights ---------------------------------------------------------------------------------------------------------------------------------- Six Months Ended Year Year Year Year Year 2/28/17 Ended Ended Ended Ended Ended (unaudited) 8/31/16 8/31/15 8/31/14 8/31/13 8/31/12 ---------------------------------------------------------------------------------------------------------------------------------- Class A Net asset value, beginning of period $ 9.56 $ 9.57 $ 9.66 $ 9.66 $ 9.72 $ 9.64 ---------------------------------------------------------------------------------------------------------------------------------- Increase (decrease) from investment operations: Net investment income (loss) $ 0.08(a) $ 0.13(a) $ 0.10 $ 0.13 $ 0.21 $ 0.28 Net realized and unrealized gain (loss) on investments 0.00(b) 0.01 (0.03) 0.02 (0.04) 0.10 ---------------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) from investment operations $ 0.08 $ 0.14 $ 0.07 $ 0.15 $ 0.17 $ 0.38 ---------------------------------------------------------------------------------------------------------------------------------- Distributions to shareowners: Net investment income $ (0.11) $ (0.15) $ (0.16) $ (0.15) $ (0.23) $ (0.30) ---------------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) in net asset value $ (0.03) $ (0.01) $ (0.09) $ -- $ (0.06) $ 0.08 ---------------------------------------------------------------------------------------------------------------------------------- Net asset value, end of period $ 9.53 $ 9.56 $ 9.57 $ 9.66 $ 9.66 $ 9.72 ================================================================================================================================== Total return* 0.82% 1.50% 0.74% 1.58% 1.71% 4.00% Ratio of total expenses to average net assets 0.82%** 0.79% 0.82% 0.79% 0.88% 0.90% Ratio of net investment income (loss) to average net assets 1.59%** 1.41% 1.12% 1.34% 1.95% 2.94% Portfolio turnover rate 76%** 44% 48% 41% 28% 43% Net assets, end of period (in thousands) $172,705 $179,870 $205,451 $ 230,938 $169,587 $55,212 Ratios with no waiver of fees and assumption of expenses by PIM and no reduction for fees paid indirectly: Total expenses to average net assets 0.82%** 0.79% 0.82% 0.79% 0.98% 1.30% Net investment income (loss) to average net assets 1.59%** 1.41% 1.12% 1.34% 1.85% 2.54% ================================================================================================================================== * 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. (b) Amount rounds to less than $0.01 per share. The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 79 Financial Highlights (continued) --------------------------------------------------------------------------------------------------------------------------------- Six Months Ended Year Year Year Year Year 2/28/17 Ended Ended Ended Ended Ended (unaudited) 8/31/16 8/31/15 8/31/14 8/31/13 8/31/12 --------------------------------------------------------------------------------------------------------------------------------- Class C Net asset value, beginning of period $ 9.54 $ 9.55 $ 9.65 $ 9.65 $ 9.70 $ 9.62 --------------------------------------------------------------------------------------------------------------------------------- Increase (decrease) from investment operations: Net investment income (loss) $ 0.06(a) $ 0.11(a) $ 0.08 $ 0.11 $ 0.15 $ 0.20 Net realized and unrealized gain (loss) on investments 0.01 0.01 (0.04) 0.02 (0.04) 0.10 --------------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) from investment operations $ 0.07 $ 0.12 $ 0.04 $ 0.13 $ 0.11 $ 0.30 --------------------------------------------------------------------------------------------------------------------------------- Distributions to shareowners: Net investment income $ (0.10) $ (0.13) $ (0.14) $ (0.13) $ (0.16) $ (0.22) --------------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) in net asset value $ (0.03) $ (0.01) $ (0.10) $ -- $ (0.05) $ 0.08 --------------------------------------------------------------------------------------------------------------------------------- Net asset value, end of period $ 9.51 $ 9.54 $ 9.55 $ 9.65 $ 9.65 $ 9.70 ================================================================================================================================= Total return* 0.69% 1.25% 0.40% 1.31% 1.09% 3.18% Ratio of total expenses to average net assets 1.05%** 1.05% 1.06% 1.06% 1.53% 1.71% Ratio of net investment income (loss) to average net assets 1.36%** 1.16% 0.87% 1.07% 1.39% 2.08% Portfolio turnover rate 76%** 44% 48% 41% 28% 43% Net assets, end of period (in thousands) $84,636 $97,028 $98,585 $ 93,355 $52,072 $24,830 Ratios with no waiver of fees and assumption of expenses by PIM and no reduction for fees paid indirectly: Total expenses to average net assets 1.05%** 1.05% 1.06% 1.06% 1.54% 1.71% Net investment income (loss) to average net assets 1.36%** 1.16% 0.87% 1.07% 1.38% 2.08% ================================================================================================================================= * 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. 80 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ------------------------------------------------------------------------------------------------------------------------ Six Months Ended Year Year Year 2/28/17 Ended Ended Ended 8/1/13 (unaudited) 8/31/16 8/31/15 8/31/14 to 8/31/13 ------------------------------------------------------------------------------------------------------------------------ Class C2 Net asset value, beginning of period $ 9.55 $ 9.56 $ 9.65 $ 9.65 $ 9.65 ------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ 0.06(a) $ 0.11(a) $ 0.08 $ 0.13 $ 0.02 Net realized and unrealized gain (loss) on investments 0.00(b) 0.01 (0.03) 0.00(b) (0.01) ------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $ 0.06 $ 0.12 $ 0.05 $ 0.13 $ 0.01 ------------------------------------------------------------------------------------------------------------------------ Distributions to shareowners: Net investment income $ (0.10) $ (0.13) $ (0.14) $ (0.13) $ (0.01) ------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ (0.04) $ (0.01) $ (0.09) $ -- $ -- ------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 9.51 $ 9.55 $ 9.56 $ 9.65 $ 9.65 ======================================================================================================================== Total return* 0.59% 1.28% 0.51% 1.37% 0.15% Ratio of total expenses to average net assets 1.05%** 1.04% 1.04% 1.05% 1.01%** Ratio of net investment income (loss) to average net assets 1.37%** 1.17% 0.90% 1.13% 2.07%** Portfolio turnover rate 76%** 44% 48% 41% 28%** Net assets, end of period (in thousands) $ 2,788 $ 2,930 $ 3,014 $ 2,934 $ 26 ======================================================================================================================== * 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. (b) Amount rounds to less than $0.01 per share. The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 81 Financial Highlights (continued) ------------------------------------------------------------------------------------- Six Months Ended 2/28/17 Year Ended 12/1/14 to (unaudited) 8/31/16 8/31/15 ------------------------------------------------------------------------------------- Class K Net asset value, beginning of period $ 9.57 $ 9.58 $ 9.65 ------------------------------------------------------------------------------------- Increase (decrease) from investment operations: Net investment income (loss) $ 0.09(a) $ 0.17(a) $ (0.18) Net realized and unrealized gain (loss) on investments 0.00(b) 0.00(b) 0.26 ------------------------------------------------------------------------------------- Net increase (decrease) from investment operations $ 0.09 $ 0.17 $ 0.08 ------------------------------------------------------------------------------------- Distribution to shareowners: Net investment income $ (0.12) $ (0.18) $ (0.15) ------------------------------------------------------------------------------------- Net increase (decrease) in net asset value $ (0.03) $ (0.01) $ (0.07) ------------------------------------------------------------------------------------- Net asset value, end of period $ 9.54 $ 9.57 $ 9.58 ===================================================================================== Total return* 0.98% 1.81% 0.84%*** Ratio of total expenses to average net assets 0.49%** 0.50% 0.50%** Ratio of net investment income (loss) to average net assets 1.93%** 1.74% 1.26%** Portfolio turnover rate 76%** 44% 48% Net assets, end of period (in thousands) $15,525 $16,502 $ 2,251 ===================================================================================== * 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. *** Not annualized. (a) The per-share data presented above is based on the average shares outstanding for the period presented. (b) Amount rounds to less than $0.01 per share. The accompanying notes are an integral part of these financial statements. 82 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ---------------------------------------------------------------------------------------------------------------------------------- Six Months Ended Year Year Year Year Year 2/28/17 Ended Ended Ended Ended Ended (unaudited) 8/31/16 8/31/15 8/31/14 8/31/13 8/31/12 ---------------------------------------------------------------------------------------------------------------------------------- Class Y Net asset value, beginning of period $ 9.54 $ 9.55 $ 9.64 $ 9.64 $ 9.70 $ 9.63 ---------------------------------------------------------------------------------------------------------------------------------- Increase (decrease) from investment operations: Net investment income (loss) $ 0.09(a) $ 0.15(a) $ 0.11 $ 0.16 $ 0.24 $ 0.31 Net realized and unrealized gain (loss) on investments 0.00(b) 0.01 (0.02) 0.02 (0.04) 0.09 ---------------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) from investment operations $ 0.09 $ 0.16 $ 0.09 $ 0.18 $ 0.20 $ 0.40 ---------------------------------------------------------------------------------------------------------------------------------- Distributions to shareowners: Net investment income $ (0.12) $ (0.17) $ (0.18) $ (0.18) $ (0.26) $ (0.33) ---------------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) in net asset value $ (0.03) $ (0.01) $ (0.09) $ -- $ (0.06) $ 0.07 ---------------------------------------------------------------------------------------------------------------------------------- Net asset value, end of period $ 9.51 $ 9.54 $ 9.55 $ 9.64 $ 9.64 $ 9.70 ================================================================================================================================== Total return* 0.93% 1.71% 0.97% 1.84% 2.03% 4.24% Ratio of total expenses to average net assets 0.61%** 0.59% 0.60% 0.57% 0.59% 0.61% Ratio of net investment income (loss) to average net assets 1.80%** 1.61% 1.33% 1.57% 2.34% 3.18% Portfolio turnover rate 76%** 44% 48% 41% 28% 43% Net assets, end of period (in thousands) $286,391 $278,689 $288,108 $ 403,710 $264,018 $132,645 ================================================================================================================================== * 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. (b) Amount rounds to less than $0.01 per share. The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 83 Notes to Financial Statements | 2/28/17 (unaudited) 1. Organization and Significant Accounting Policies Pioneer Short Term Income Fund (the Fund) is a Delaware statutory trust 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 Y shares. 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: 84 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 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 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. Futures contracts are generally valued at the closing settlement price established by the exchange on which they are traded. 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. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 85 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 Pioneer Investment Management, Inc. (PIM), the Fund's investment adviser and a wholly owned indirect subsidiary of UniCredit S.p.A. (UniCredit), pursuant to procedures adopted by the Fund's Board of Trustees. PIM's fair valuation team uses fair value methods approved by the Valuation Committee of the Board of Trustees. PIM'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 February 28, 2017, there were no securities 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. 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. Interest income, including 86 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 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. 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 gain or loss 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. As of August 31, 2016, the Fund did not accrue any interest or penalties related 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. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 87 The tax character of current year distributions payable will be determined at the end of the current taxable year. The tax character of distributions during the year ended August 31, 2016 was as follows: --------------------------------------------------------------------------- 2016 --------------------------------------------------------------------------- Distributions paid from: Ordinary income $ 9,845,537 --------------------------------------------------------------------------- Total $ 9,845,537 =========================================================================== The following shows the components of distributable earnings (losses) on a federal income tax basis at August 31, 2016: --------------------------------------------------------------------------- 2016 --------------------------------------------------------------------------- Distributable earnings: Undistributed ordinary income $ 1,216,516 Capital loss carryforward (13,457,025) Current year dividend payable (141,721) Unrealized depreciation (1,789,242) --------------------------------------------------------------------------- Total $ (14,171,472) =========================================================================== The difference between book-basis and tax-basis net unrealized depreciation is attributable to the tax deferral on wash sales, adjustments relating to catastrophe bonds and reinsurance sidecars, the tax treatment of premium and amortization and the market to market of futures contracts. E. Fund Shares The Fund records sales and repurchases of its shares as of trade date. Pioneer Funds Distributor, Inc. (PFD), the principal underwriter for the Fund and a wholly owned indirect subsidiary of UniCredit, earned $2,751 in underwriting commissions on the sale of Class A shares during the six months ended February 28, 2017. F. 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, Class C2, and Class K 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). 88 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 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 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. 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. Investments in the Fund are subject to possible loss due to the financial failure of underlying issuers and their inability to meet their debt obligations. 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 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 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 89 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. 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. PIM 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. For the six months ended February 28, 2017, the Fund had no open repurchase agreements. 90 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 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 February 28, 2017 was $513,000 and is included in "Restricted Cash" in 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. The use of 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 February 28, 2017 was $127,016,702. At February 28, 2017, open futures contracts were as follows: --------------------------------------------------------------------------------------- Number of Unrealized Contracts Settlement Appreciation Description Counterparty Long/(Short) Month Value (Depreciation) --------------------------------------------------------------------------------------- U.S. Treasury 2 Year Note Citibank NA 487 06/17 $111,296,422 $82,985 --------------------------------------------------------------------------------------- Total $111,296,422 $82,985 ======================================================================================= 2. Management Agreement PIM manages the Fund's portfolio. Management fees are calculated daily at the annual rate of 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 February 28, 2017, the effective management fee (excluding waivers and/or assumption of expenses) was equivalent to 0.35% 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 $23,027 in management fees, administrative costs and certain other reimbursements payable to PIM at February 28, 2017. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 91 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 February 28, 2017, such out-of-pocket expenses by class of shares were as follows: -------------------------------------------------------------------------------- Shareholder Communications: -------------------------------------------------------------------------------- Class A $7,656 Class C 18 Class C2 1 Class K 51 Class Y 180 -------------------------------------------------------------------------------- Total $7,906 ================================================================================ 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 PFD 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. Further pursuant to the Plan, the Fund also pays PFD 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 $8,592 in distribution fees payable to PFD at February 28, 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 and Class C2 shares within 12 months of purchase are subject to a CDSC of 1.00%, based on 92 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 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 PFD. For the six months ended February 28, 2017, CDSCs in the amount of $1,091 were paid to PFD. 5. 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 Portfolio. 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 February 28, 2017 was as follows: -------------------------------------------------------------------------------- Foreign Statement of Interest Credit Exchange Equity Commodity Assets and Liabilities Rate Risk Risk Rate Risk Risk Risk -------------------------------------------------------------------------------- Liabilities Net unrealized depreciation of futures contracts* $82,985 $ -- $ -- $ -- $ -- -------------------------------------------------------------------------------- Total Value $82,985 $ -- $ -- $ -- $ -- ================================================================================ * Reflects unrealized appreciation/depreciation of futures contracts (see Note 1J). The current day's variation margin is disclosed on the Statement of Assets and Liabilities. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 93 The effect of derivative instruments (not considered to be hedging instruments for accounting disclosure purposes) on the Statement of Operations by risk exposure at February 28, 2017 was as follows: -------------------------------------------------------------------------------- Foreign Statement of Interest Credit Exchange Equity Commodity Operations Rate Risk Risk Rate Risk Risk Risk -------------------------------------------------------------------------------- Net realized gain (loss) on Futures contracts $(566,856) $ -- $ -- $ -- $ -- -------------------------------------------------------------------------------- Total Value $(566,856) $ -- $ -- $ -- $ -- ================================================================================ Change in net unrealized appreciation (depreciation) on Futures contracts $ 136,081 $ -- $ -- $ -- $ -- -------------------------------------------------------------------------------- Total Value $ 136,081 $ -- $ -- $ -- $ -- ================================================================================ 94 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 ADDITIONAL INFORMATION Pioneer Investment Management, Inc. (the "Adviser"), the Fund's investment adviser, is currently an indirect, wholly owned subsidiary of UniCredit S.p.A. ("UniCredit"). On December 12, 2016, UniCredit announced that it has entered into a binding agreement for the sale of its Pioneer Investments business, which includes the Adviser, to Amundi (the "Transaction"). Amundi is headquartered in Paris, France, and, as of September 30, 2016, had more than $1.1 trillion in assets under management worldwide. The closing of the Transaction is expected to happen in 2017, subject to certain regulatory and antitrust approvals, and other conditions. Under the Investment Company Act of 1940, the closing of the Transaction will cause the Fund's current investment advisory agreement with the Adviser to terminate. Accordingly, the Fund's Board of Trustees has approved a new investment advisory agreement for the Fund, which will be submitted to the shareholders of the Fund for their approval. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 95 Approval of Investment Advisory Agreement Pioneer Investment Management, Inc. (PIM) serves as the investment adviser to Pioneer Short Term Income Fund (the Fund) pursuant to an investment advisory agreement between PIM and the Fund. In order for PIM to remain the investment adviser of the Fund, the Trustees of the Fund must determine annually whether to renew the investment advisory agreement for the Fund. The contract review process began in January 2016 as the Trustees of the Fund agreed on, among other things, an overall approach and timeline for the process. Contract review materials were provided to the Trustees in March 2016 and May 2016. In addition, the Trustees reviewed and discussed the Fund's performance at regularly scheduled meetings throughout the year, and took into account other information related to the Fund provided to the Trustees at regularly scheduled meetings, in connection with the review of the Fund's investment advisory agreement. In March 2016, the Trustees, among other things, discussed the memorandum provided by Fund counsel that summarized the legal standards and other considerations that are relevant to the Trustees in their deliberations regarding the renewal of the investment advisory agreement, and reviewed and discussed the qualifications of the investment management teams, as well as the level of investment by the Fund's portfolio managers in the Fund. In May 2016, the Trustees, among other things, reviewed the Fund's management fee and total expense ratios, the financial statements of PIM and its parent companies, the profitability analyses provided by PIM, and possible economies of scale. The Trustees also reviewed the profitability of the institutional business of PIM and PIM's affiliate, Pioneer Institutional Asset Management, Inc. (together with PIM, "Pioneer"), as compared to that of PIM's fund management business, and considered the differences between the fees and expenses of the Fund and the fees and expenses of Pioneer's institutional accounts, as well as the different services provided by PIM to the Fund and by Pioneer to the institutional accounts. The Trustees further considered contract review materials in July and September 2016. At a meeting held on September 13, 2016, based on their evaluation of the information provided by PIM and third parties, the Trustees of the Fund, including the Independent Trustees voting separately, unanimously approved the renewal of the investment advisory agreement for another year. In approving the renewal of the investment advisory agreement, the Trustees considered various factors that they determined were relevant, including the factors described below. The Trustees did not identify any single factor as the controlling factor in determining to approve the renewal of the agreement. 96 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 Nature, Extent and Quality of Services The Trustees considered the nature, extent and quality of the services that had been provided by PIM to the Fund, taking into account the investment objective and strategy of the Fund. The Trustees also reviewed PIM's investment approach for the Fund and its research process. The Trustees considered the resources of PIM and the personnel of PIM who provide investment management services to the Fund. They also reviewed the amount of non-Fund assets managed by the portfolio managers of the Fund. The Trustees considered the non-investment resources and personnel of PIM involved in PIM's services to the Fund, including PIM's compliance and legal resources and personnel. The Trustees noted the substantial attention and high priority given by PIM's senior management to the Pioneer fund complex. The Trustees considered that PIM supervises and monitors the performance of the Fund's service providers and provides the Fund with personnel (including Fund officers) and other resources that are necessary for the Fund's business management and operations. The Trustees also considered that, as administrator, PIM is responsible for the administration of the Fund's business and other affairs. The Trustees considered the fees paid to PIM for the provision of administration services. Based on these considerations, the Trustees concluded that the nature, extent and quality of services that had been provided by PIM to the Fund were satisfactory and consistent with the terms of the investment advisory agreement. Performance of the Fund In considering the Fund's performance, the Trustees regularly review and discuss throughout the year data prepared by PIM and information comparing the Fund's performance with the performance of its peer group of funds as classified by each of Morningstar, Inc. (Morningstar) and Lipper, and with the performance of the Fund's benchmark index. They also discuss the Fund's performance with PIM on a regular basis. The Trustees' regular reviews and discussions were factored into the Trustees' deliberations concerning the renewal of the advisory agreement. Management Fee and Expenses The Trustees considered information showing the fees and expenses of the Fund in comparison to the management fees and expense ratios of its peer group of funds as classified by Morningstar and also to the expense ratios of a peer group of funds selected on the basis of criteria determined by the Independent Trustees for this purpose using data provided by Strategic Insight Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 97 Mutual Fund Research and Consulting, LLC (Strategic Insight), an independent third party. In all quintile rankings referred to below, first quintile is most favorable to the Fund's shareowners. The Trustees considered that the Fund's management fee for the most recent fiscal year was in the second quintile relative to the management fees paid by other funds in its Morningstar peer group for the comparable period. The Trustees also considered the breakpoint in the management fee schedule and the reduced fee rate above a certain asset level. The Trustees considered that the expense ratio of the Fund's Class A shares for the most recent fiscal year was in the fourth quintile relative to its Morningstar peer group and in the third quintile relative to its Strategic Insight peer group, in each case for the comparable period. The Trustees considered that the expense ratio of the Fund's Class Y shares for the most recent fiscal year was in the fourth quintile relative to its Morningstar peer group and in the fourth quintile relative to its Strategic Insight peer group, in each case for the comparable period. The Trustees considered that the expense ratio of the Fund's Class A shares was approximately two basis points higher than the median expense ratio paid by other funds in its Morningstar peer group. The Trustees considered the impact of transfer agency, sub-transfer agency and other non-management fee expenses on the expense ratios of the Fund, and noted the impact of expenses relating to small accounts and omnibus accounts on transfer and sub-transfer agency expenses generally. The Trustees noted that they separately review the Fund's transfer agency, sub-transfer agency and intermediary arrangements and that the results of the most recent such review were considered in the consideration of the Fund's expense ratio. The Trustees reviewed management fees charged by Pioneer to institutional and other clients, including publicly offered European funds sponsored by affiliates of Pioneer, unaffiliated U.S. registered investment companies (in a sub-advisory capacity), and unaffiliated foreign and domestic separate accounts. The Trustees also considered PIM's costs in providing services to the Fund and Pioneer's costs in providing services to the other clients and considered the differences in management fees and profit margins for Fund and non-Fund services. In evaluating the fees associated with Pioneer's client accounts, the Trustees took into account the respective demands, resources and complexity associated with the Fund and client accounts. The Trustees noted that, in some instances, the fee rates for those clients were lower than the management fee for the Fund and considered that, under the investment advisory agreement with the Fund, PIM performs additional services for the Fund that it does not provide to those other clients or services that are broader 98 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 in scope, including oversight of the Fund's other service providers and activities related to compliance and the extensive regulatory and tax regimes to which the Fund is subject. The Trustees also considered the different entrepreneurial risks associated with PIM's management of the Fund and Pioneer's management of the other client accounts. The Trustees concluded that the management fee payable by the Fund to PIM was reasonable in relation to the nature and quality of the services provided by PIM to the Fund. Profitability The Trustees considered information provided by PIM regarding the profitability of PIM with respect to the advisory services provided by PIM to the Fund, including the methodology used by PIM in allocating certain of its costs to the management of the Fund. The Trustees also considered PIM's profit margin in connection with the overall operation of the Fund. They further reviewed the financial results, including the profit margins, realized by PIM and its affiliates from non-fund businesses. The Trustees considered PIM's profit margins with respect to the Fund in comparison to the limited industry data available and noted that the profitability of any adviser was affected by numerous factors, including its organizational structure and method for allocating expenses. The Trustees concluded that PIM's profitability with respect to the management of the Fund was not unreasonable. Economies of Scale The Trustees considered PIM's views relating to economies of scale in connection with the Pioneer Funds as fund assets grow and the extent to which any such economies of scale are shared with funds and fund shareholders. The Trustees noted the breakpoint in the management fee schedule. The Trustees recognize that economies of scale are difficult to identify and quantify, and that, among other factors that may be relevant, are the following: fee levels, expense subsidization, investment by PIM in research and analytical capabilities and PIM's commitment and resource allocation to the Fund. The Trustees noted that profitability also may be an indicator of the availability of any economies of scale, although profitability may vary for other reasons including reductions in expenses. The Trustees concluded that economies of scale, if any, were being appropriately shared with the Funds. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 99 Other Benefits The Trustees considered the other benefits to PIM from its relationship with the Fund. The Trustees considered the character and amount of fees paid by the Fund, other than under the investment advisory agreement, for services provided by PIM and its affiliates. The Trustees further considered the revenues and profitability of PIM's businesses other than the fund business. Pioneer is the principal U.S. asset management business of Pioneer Global Asset Management, the worldwide asset management business of UniCredit Group, which manages over $150 billion in assets (including the Funds). Pioneer and the Funds receive reciprocal intangible benefits from the relationship, including mutual brand recognition and, for the Funds, direct and indirect access to the resources of a large global asset manager. The Trustees concluded that any such benefits received by Pioneer as a result of its relationship with the Funds were reasonable and their consideration of the advisory agreement between the Fund and PIM and the fees thereunder were unaffected by Pioneer's possible receipt of any such intangible benefits. Conclusion After consideration of the factors described above as well as other factors, the Trustees, including all of the Independent Trustees, concluded that the investment advisory agreement between PIM and the Fund, including the fees payable thereunder, was fair and reasonable and voted to approve the proposed renewal of the investment advisory agreement for the Fund. 100 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 Trustees, Officers and Service Providers Trustees Advisory Trustee Thomas J. Perna, Chairman Lorraine H. Monchak* David R. Bock Benjamin M. Friedman Officers Margaret B.W. Graham Lisa M. Jones, President and Chief Marguerite A. Piret Executive Officer Fred J. Ricciardi Mark E. Bradley, Treasurer and Kenneth J. Taubes Chief Financial Officer Christopher J. Kelley, Secretary and Chief Legal Officer Investment Adviser and Administrator Pioneer Investment Management, Inc. Custodian and Sub-Administrator Brown Brothers Harriman & Co. Principal Underwriter Pioneer Funds 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 us.pioneerinvestments.com. This information is also available on the Securities and Exchange Commission's web site at www.sec.gov. * Ms. Monchak is a non-voting Advisory Trustee. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 101 This page is for your notes. 102 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 This page is for your notes. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 103 This page is for your notes. 104 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 This page is for your notes. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 105 This page is for your notes. 106 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 This page is for your notes. Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 107 This page is for your notes. 108 Pioneer Short Term Income Fund | Semiannual Report | 2/28/17 How to Contact 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: -------------------------------------------------------------------------------- Pioneer Funds P.O. Box 55014 Boston, Massachusetts 02205-5014 Our toll-free fax 1-800-225-4240 Our internet e-mail address ask.pioneer@pioneerinvestments.com (for general questions about Pioneer only) Visit our web site: us.pioneerinvestments.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] PIONEER Investments(R) Pioneer Investment Management, Inc. 60 State Street Boston, MA 02109 us.pioneerinvestments.com Securities offered through Pioneer Funds Distributor, Inc. 60 State Street, Boston, MA 02109 Underwriter of Pioneer Mutual Funds, Member SIPC (C) 2017 Pioneer Investments 19127-11-0417 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 Short Term Income Fund By (Signature and Title)* /s/ Lisa M. Jones Lisa M. Jones, President & Chief Executive Officer Date May 1, 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 May 1, 2017 By (Signature and Title)* /s/ Mark E. Bradley Mark E. Bradley, Treasurer & Chief Accounting & Financial Officer Date May 1, 2017 * Print the name and title of each signing officer under his or her signature.