OMB APPROVAL OMB Number: 3235-0570 Expires: August 31, 2013 Estimated average burden hours per response.....18.9 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, 2012 through February 28, 2013 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 SHAREOWNERS. Pioneer Short Term Income Fund -------------------------------------------------------------------------------- Semiannual Report | February 28, 2013 -------------------------------------------------------------------------------- Ticker Symbols: Class A STABX Class B STBBX Class C PSHCX Class Y PSHYX [LOGO] PIONEER Investments(R) visit us: us.pioneerinvestments.com Table of Contents Letter to Shareowners 2 Portfolio Management Discussion 4 Portfolio Summary 9 Prices and Distributions 10 Performance Update 11 Comparing Ongoing Fund Expenses 15 Schedule of Investments 17 Financial Statements 51 Notes to Financial Statements 59 Approval of Investment Advisory Agreement 68 Trustees, Officers and Service Providers 72 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 1 President's Letter Dear Shareowner, Pioneer has been cautiously optimistic about the U.S. economy from the start of the year, and the data continues to be encouraging. Employment continues to rise, albeit slowly, and we believe it should continue to do so in 2013, barring a negative shock to the system. The housing and auto sectors continue to recover, benefiting from record-low interest rates. Banks' willingness to lend to consumers and businesses also continues to rise, broad measures of inflation remain subdued, and, if the weather improves in 2013, that should help to bring food prices back down. While corporate profit growth has slowed, many U.S. companies still have strong balance sheets and continue to display the ability to both pay and increase dividends*. While the so-called "fiscal cliff" scheduled to take effect at year-end dominated the media in December--and while no deal was struck before markets closed for the year--investors who owned financial assets like equities and high-yield corporate bonds generally enjoyed good returns in 2012. The Standard & Poor's 500 Index returned 16% in 2012, and the Bank of America Merrill Lynch High Yield Master II Index returned 15.6%. Meanwhile, the higher-quality Barclays Aggregate Bond Index gained 4.2% for the year, the safer-still Barclays Intermediate Treasuries Index returned 3.9%, and 3-month Treasury bills, generally regarded as essentially "risk free" by the markets, returned just 0.1% in 2012. Despite generally improving economic conditions and positive market returns in 2012, investors still face daunting challenges in the year ahead, although we remain optimistic that the underlying economic trends are moving in the right direction. The year-end "fiscal cliff" deal did not eliminate the risk of further tax increases or spending cuts, nor did it eliminate the risk that the U.S. could face further downgrades to its credit rating from one or more of the major ratings agencies. The Federal Reserve Board continues to provide extraordinary support to the U.S. economy and the bond market, but will not do so indefinitely. Europe has made progress towards dampening its sovereign-debt crisis, but has not resolved the problem as yet; the region also was mired in a recession as 2012 drew to a close. In Asia, Japan continues to struggle with low economic growth, * Dividends are not guaranteed. 2 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 deflation, high levels of debt, and an aging population. In the emerging markets, China and other developing economies, while generally in better shape than most "developed" markets, also face a range of ongoing challenges. While most of the risks outlined above are widely recognized and may already be "priced in" to the market, we believe investors should continue to expect market volatility tied to these factors. At Pioneer, we have long advocated the benefits of staying diversified* and investing for the long term. And while diversification alone does not assure a profit or protect against loss in a declining market, we believe there are still opportunities for prudent investors to earn attractive returns. Our advice, as always, is to work closely with a trusted financial advisor to discuss your goals and work together to develop an investment strategy that meets your individual needs, keeping in mind that there is no single best strategy that works for every investor. In 2013, Pioneer proudly celebrates its 85th anniversary. Since 1928, our investment teams have sought out attractive opportunities in global equity and bond markets, using in-depth research to identify undervalued individual securities, and using thoughtful risk management to construct portfolios which balance potential risks and reward in an ever-changing world. We encourage you to learn more about Pioneer and our time-tested approach to investing by consulting with your financial advisor or visiting us online at us.pioneerinvestments.com. We greatly appreciate your trust in us, and we thank you for investing with Pioneer. Sincerely, /s/ Daniel K. Kingsbury Daniel K. Kingsbury President and CEO Pioneer Investment Management USA, Inc. 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. These statements should not be relied upon for any other purposes. Past performance is no guarantee of future results, and there is no guarantee that market forecasts discussed will be realized. * Diversification does not assure a profit nor protect against loss in a declining market. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 3 Portfolio Management Discussion | 2/28/13 In the following interview, Richard Schlanger and Charles Melchreit, portfolio managers of Pioneer Short Term Income Fund, discuss the factors that influenced the Fund's performance over the six-month period ended February 28, 2013. Mr. Schlanger, vice president and portfolio manager at Pioneer, and Mr. Melchreit, vice president and portfolio manager at Pioneer, are responsible for the day-to-day management of the Fund. Q How would you describe the market environment for fixed-income investors during the six-month period ended February 28, 2013? A The period began last September against a backdrop of continued concern over the European sovereign-debt crisis and its potential to undermine the global economy. Fortunately, central banks around the globe soon would step forward with more accommodative fiscal policies. First, the European Central Bank cut its overnight deposit rate to zero, and announced it would ease refinancing conditions and greatly lower the risk of sovereign default by committing to open-ended purchases of short-term debt issued by troubled nations within the euro zone. Then, citing continued unacceptably weak employment conditions, the U.S. Federal Reserve (the Fed) announced further plans for bond purchases, including government agency mortgages, under its third round of quantitative easing (QE3), and also committed to maintaining short-term interest rates at near zero for the time being. The prospect of prolonged and widespread monetary support for the global economy, along with clear evidence of a rebound in U.S. housing, helped to support the risk-oriented sectors into the fall of 2012. Toward the end of 2012, however, positive investor sentiment driven by the Fed's actions and signs of strength in key sectors, such as housing, would be offset somewhat by headlines about the debate in Washington over the U.S. government's fiscal policies. In particular, following the November U.S. elections, investors focused on the political stalemate that threatened the U.S. economy with automatic budget cuts and tax increases--the so-called "fiscal cliff." That scenario, ultimately, was narrowly averted at year-end. Early 2013 saw significant strengthening in U.S. auto and housing data as well as modest, ongoing improvement in employment--news that added to the sense that the U.S. economic recovery was gaining traction. There also was evidence that China would maintain economic growth at levels sufficient to meaningfully support the global economy. 4 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 Throughout the six-month period, the Fed continued to underpin conditions through its low-interest-rate policy and QE3. Nonetheless, interest rates rose modestly between August 31, 2012, and February 28, 2013. To illustrate, the two-year Treasury yield rose by three basis points (0.03%), from 0.22% to 0.25%, the five-year Treasury yield rose by 18 basis points (0.18%), from 0.59% to 0.77%, and the 10-year Treasury yield rose by 32 basis points (0.32%), from 1.57% to 1.89%. Credit spreads generally narrowed over the six-month period, supported in part by extraordinarily low Treasury yields that held little appeal to income-oriented investors (credit spreads are commonly defined as the differences in yield between Treasury securities and other fixed-income securities with similar maturities). Q How did the Fund perform in that environment during the six months ended February 28, 2013? A Pioneer Short Term Income Fund's Class A shares returned 1.42% at net asset value during the six months ended February 28, 2013, while the Fund's benchmark, the Barclays One- to Three-Year Government/Credit Index (the Barclays Index), returned 0.40%. During the same period, the average return of the 278 mutual funds in Lipper's Short Investment-Grade Debt Funds category was 1.07%. Q Which of your investment strategies had the biggest effects on the Fund's performance during the six months ended February 28, 2013? A Allocation of assets among the fixed-income sectors was the largest overall contributor to the Fund's performance during the period. Throughout the period, we maintained sharply reduced portfolio exposure to U.S. Treasury issues, reflecting our view that Treasuries have not been valued attractively compared with credit-sensitive securities, given Treasuries' negative real yields (or yields after accounting for inflation). The decision to underweight the Fund to Treasuries helped returns relative to the Barclays Index, as the credit-sensitive sectors outperformed over the six-month period. Much of the portfolio's underweight to Treasuries was deployed in sectors that are not included in the benchmark Barclays Index, and that strategy worked out well for the Fund. The non-benchmark investments included those in a variety of pass-through sectors, such as residential and commercial mortgage-backed securities (MBS), as well as asset-backed securities (ABS), including ABS backed by home equity loans, auto loans and credit card receivables. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 5 At the security level, the Fund's significant positions in securities backed by pools of residential mortgages were the biggest positive contributors to performance during the six-month period. Within that group, we saw opportunities to add high-quality issues to the portfolio at attractive valuations, and the holdings performed well as investor sentiment regarding the housing market improved over the six-month period. The Fund's substantial position in ABS benefited from strengthened investor sentiment about credit, as economic conditions improved. Finally, the Fund had a modest position in so-called "catastrophe" (CAT) bonds, which are sponsored by insurance companies seeking to protect themselves against the financial impact of a specific natural disaster. In addition to providing a diversification* benefit to the portfolio, the incremental income provided by the CAT bonds, compared with the income offered by most other fixed-income sectors, contributed to the Fund's benchmark-relative returns during the period. On the downside, the performance of the Fund's commercial MBS holdings was negatively affected by faster-than-expected prepayments. The Fund's overall duration at the end of February was 0.96 years, compared with 1.90 years for the Barclays Index. The Fund's shorter-duration stance was a slight positive for benchmark-relative returns, as interest rates rose over the full six-month period (duration is a measure of a portfolio's price sensitivity to changes in interest rates). Q What is your assessment of the current climate for fixed-income investing and how is that view reflected in the Fund's positioning? A While the U.S. employment picture has improved, there is still a significant distance to travel before overall labor utilization reaches healthy levels by historical standards. Given that backdrop, we do not expect the Fed to remove its accommodative policies for at least the next several months. That said, even absent certain factors that would lead to dramatic increases in interest rates, there clearly continues to be much more room for rates to rise from current levels rather than for them to fall. As a result, we are comfortable with maintaining an overall portfolio duration that is below that of the Barclays Index benchmark. We also have added floating-rate securities to the portfolio as a measure of protection in the event the market begins to price in a sooner-than-expected removal of the Fed's accommodative policies. * Diversification does not assure a profit nor protect against loss in a declining market. 6 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 We continue to view credit sectors that trade at a yield spread over Treasuries as attractive on a relative basis. While we have continued to underweight the Fund to Treasuries, given the recent tightening of spreads following the recent outperformance of the credit sectors, we have been trimming (at the margin) the proportion of MBS and ABS held in the portfolio, while adding modestly to the Fund's Treasury position. We view current fundamentals as continuing to be supportive of corporate issues, especially given the high levels of cash still appearing on many balance sheets and a favorable financing environment. With credit spreads having narrowed, however, we view corporate valuations as a neutral factor overall, and we are being selective in adding credit-sensitive exposure to the portfolio. We believe that opportunities to add to the Fund's benchmark-relative performance over the near-to-intermediate term are more likely to be driven by individual security selection than by adding credit risk. We will continue to monitor macroeconomic factors that have the potential to affect the markets, while remaining principally focused on adding value for the Fund's shareholders at the individual security selection level. As always, we will seek to maintain a portfolio that provides a high level of current income, while limiting the effects of changes in interest rates on the Fund's share price. Please refer to the Schedule of Investments on pages 17-51 for a full listing of Fund securities. 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 mortgage-backed bonds will be paid off early if falling interest rates prompt homeowners to refinance their mortgages. 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 associated with falling interest rates. 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. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 7 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 it more susceptible to any economic, political, or regulatory developments or other risks affecting those industries and sectors. These risks may increase share price volatility. Past performance is not a guarantee of future results, and there is no guarantee that market forecasts discussed will be realized. 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. These statements should not be relied upon for any other purposes. 8 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 Portfolio Summary | 2/28/13 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 30.7% U.S. Corporate Bonds 18.6% U.S. Government Securities 18.3% Asset Backed Securities 16.4% International Corporate Bonds 10.3% Municipal Bonds 3.4% Senior Secured Loans 2.3% Portfolio Quality -------------------------------------------------------------------------------- (As a percentage of total investment portfolio; based on S&P ratings) [THE FOLLOWING DATA WAS REPRESENTED AS A PIE CHART IN THE PRINTED MATERIAL] AAA 35.7% AA 13.0% A 18.1% BBB 20.7% BB 6.9% B 1.7% CCC 1.2% Not Rated 2.7% Bond ratings are ordered highest to lowest in portfolio. Based on Standard & Poor's measures, AAA (highest possible rating) through BBB are considered investment grade; BB or lower ratings are considered non-investment grade. Cash equivalents and some bonds may not be rated. 10 Largest Holdings -------------------------------------------------------------------------------- (As a percentage of total debt holdings)* 1. U.S. Treasury Notes, 0.125%, 9/30/13 6.04% ------------------------------------------------------------------------------------------- 2. U.S. Treasury Notes, 0.25%, 10/31/13 4.12 ------------------------------------------------------------------------------------------- 3. U.S. Treasury Notes, 0.125%, 12/31/13 3.18 ------------------------------------------------------------------------------------------- 4. Fannie Mae Grantor Trust 2001-T1, Floating Rate Note, 10/25/40 1.53 ------------------------------------------------------------------------------------------- 5. U.S. Treasury Notes, 0.5%, 11/15/13 1.31 ------------------------------------------------------------------------------------------- 6. State of California, 2.5%, 6/20/13 0.75 ------------------------------------------------------------------------------------------- 7. HSBC Bank Plc, Floating Rate Note, 1/17/14 (144A) 0.64 ------------------------------------------------------------------------------------------- 8. Residential Asset Securitization Trust 2003-A2, Floating Rate Note, 5/25/33 0.63 ------------------------------------------------------------------------------------------- 9. Impac CMB Trust Series 2004-4, Floating Rate Note, 9/25/34 0.58 ------------------------------------------------------------------------------------------- 10. Banc of America Mortgage 2003-H Trust, Floating Rate Note, 9/25/33 0.57 ------------------------------------------------------------------------------------------- * This list excludes temporary cash investments and derivative instruments. The portfolio is actively managed and current holdings may be different. The holdings listed should not be considered recommendations to buy or sell any security listed. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 9 Prices and Distributions | 2/28/13 Net Asset Value per Share -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Class 2/28/13 8/31/12 -------------------------------------------------------------------------------- A $9.73 $9.72 -------------------------------------------------------------------------------- B $9.72 $9.71 -------------------------------------------------------------------------------- C $9.71 $9.70 -------------------------------------------------------------------------------- Y $9.71 $9.70 -------------------------------------------------------------------------------- Distributions per Share: 9/1/12-2/28/13 -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Net Investment Short-Term Long-Term Class Income Capital Gains Capital Gains -------------------------------------------------------------------------------- A $0.1272 $ -- $ -- -------------------------------------------------------------------------------- B $0.0834 $ -- $ -- -------------------------------------------------------------------------------- C $0.0906 $ -- $ -- -------------------------------------------------------------------------------- Y $0.1432 $ -- $ -- -------------------------------------------------------------------------------- The Barclays One- to Three-Year Government/Credit Index measures 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 11-14. 10 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 Performance Update | 2/28/13 Class A Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $10,000 investment made in Pioneer Short Term Income Fund, at public offering price, compared to that of the Barclays One- to Three-Year Government/Credit Index. Average Annual Total Returns (As of February 28, 2013) -------------------------------------------------------------------------------- Net Asset Public Offering Period Value (NAV) Price (POP) -------------------------------------------------------------------------------- Life-of-Class (7/8/04) 3.38% 3.07% 5 Years 3.46 2.94 1 Year 3.51 0.90 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated December 31, 2012) -------------------------------------------------------------------------------- Gross Net -------------------------------------------------------------------------------- 1.30% 0.90% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Pioneer Short-Term Barclays One- to Three-Year Income Fund Government/Credit Index 7/31/2004 $ 9,750 $ 10,000 2/28/2005 $ 9,816 $ 10,062 2/28/2006 $ 9,986 $ 10,294 2/28/2007 $ 10,438 $ 10,810 2/29/2008 $ 10,960 $ 11,732 2/28/2009 $ 10,504 $ 12,009 2/28/2010 $ 11,774 $ 12,581 2/28/2011 $ 12,264 $ 12,830 2/29/2012 $ 12,552 $ 13,055 2/28/2013 $ 12,992 $ 13,194 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 net expense ratio reflects contractual expense limitations currently in effect through January 1, 2014, for Class A shares. There can be no assurance that Pioneer will extend the expense limitations beyond such time. Please see the prospectus and financial statements for more information. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 11 Performance Update | 2/28/13 Class B Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $10,000 investment made in Pioneer Short Term Income Fund, compared to that of the Barclays One- to Three-Year Government/Credit Index. Average Annual Total Returns (As of February 28, 2013) -------------------------------------------------------------------------------- If If Period Held Redeemed -------------------------------------------------------------------------------- Life-of-Class (7/8/04) 2.47% 2.47% 5 Years 2.53 2.53 1 Year 2.59 0.59 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated December 31, 2012) -------------------------------------------------------------------------------- Gross Net -------------------------------------------------------------------------------- 1.99% 1.80% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Pioneer Short-Term Barclays One- to Three-Year Income Fund Government/Credit Index 7/31/2004 $ 10,000 $ 10,000 2/28/2005 $ 10,031 $ 10,062 2/28/2006 $ 10,121 $ 10,294 2/28/2007 $ 10,489 $ 10,810 2/29/2008 $ 10,905 $ 11,732 2/28/2009 $ 10,355 $ 12,009 2/28/2010 $ 11,516 $ 12,581 2/28/2011 $ 11,877 $ 12,830 2/29/2012 $ 12,047 $ 13,055 2/28/2013 $ 12,359 $ 13,194 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. "If Redeemed" results reflect the deduction of the maximum applicable contingent deferred sales charge (CDSC). The maximum CDSC is 2% and declines over three years. "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 net expense ratio reflects contractual expense limitations currently in effect through January 1, 2014, for Class B shares. There can be no assurance that Pioneer will extend the expense limitations beyond such time. Please see the prospectus and financial statements for more information. The performance table and graph do not reflect the deduction of taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. 12 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 Performance Update | 2/28/13 Class C Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $10,000 investment made in Pioneer Short Term Income Fund, compared to that of the Barclays One- to Three-Year Government/Credit Index. Average Annual Total Returns (As of February 28, 2013) -------------------------------------------------------------------------------- If If Period Held Redeemed -------------------------------------------------------------------------------- Life-of-Class (7/8/04) 2.55% 2.55% 5 Years 2.64 2.64 1 Year 2.80 2.80 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated December 31, 2012) -------------------------------------------------------------------------------- Gross -------------------------------------------------------------------------------- 1.71% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Pioneer Short-Term Barclays One- to Three-Year Income Fund Government/Credit Index 7/31/2004 $ 10,000 $ 10,000 2/28/2005 $ 10,042 $ 10,062 2/28/2006 $ 10,110 $ 10,294 2/28/2007 $ 10,486 $ 10,810 2/29/2008 $ 10,920 $ 11,732 2/28/2009 $ 10,379 $ 12,009 2/28/2010 $ 11,537 $ 12,581 2/28/2011 $ 11,925 $ 12,830 2/29/2012 $ 12,102 $ 13,055 2/28/2013 $ 12,440 $ 13,194 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 are also subject to a 1% contingent deferred sales charge (CDSC). "If Held" results represent the percent change in net asset value per share. Returns would have been lower had sales charges been reflected. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ. Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 13 Performance Update | 2/28/13 Class Y Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $5 million investment made in Pioneer Short Term Income Fund, compared to that of the Barclays One- to Three-Year Government/Credit Index. Average Annual Total Returns (As of February 28, 2013) -------------------------------------------------------------------------------- If If Period Held Redeemed -------------------------------------------------------------------------------- Life-of-Class (7/8/04) 3.72% 3.72% 5 Years 3.77 3.77 1 Year 3.85 3.85 -------------------------------------------------------------------------------- Expense Ratio (Per prospectus dated December 31, 2012) -------------------------------------------------------------------------------- Gross -------------------------------------------------------------------------------- 0.61% -------------------------------------------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $5 Million Investment Pioneer Short-Term Barclays One- to Three-Year Income Fund Government/Credit Index 7/31/2004 $ 5,000,000 $ 5,000,000 2/28/2005 $ 5,057,307 $ 5,031,162 2/28/2006 $ 5,156,324 $ 5,146,787 2/28/2007 $ 5,414,585 $ 5,404,881 2/29/2008 $ 5,701,140 $ 5,865,962 2/28/2009 $ 5,471,510 $ 6,004,495 2/28/2010 $ 6,157,941 $ 6,290,306 2/28/2011 $ 6,436,466 $ 6,415,007 2/29/2012 $ 6,604,899 $ 6,527,462 2/28/2013 $ 6,859,139 $ 6,596,892 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. 14 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 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, 2012, through February 28, 2013. -------------------------------------------------------------------------------- Share Class A B C Y -------------------------------------------------------------------------------- Beginning Account $1,000.00 $1,000.00 $1,000.00 $1,000.00 Value on 9/1/12 -------------------------------------------------------------------------------- Ending Account $1,014.20 $1,009.60 $1,010.40 $1,015.90 Value (after expenses) on 2/28/13 -------------------------------------------------------------------------------- Expenses Paid $4.49 $8.77 $8.32 $3.05 During Period* -------------------------------------------------------------------------------- * Expenses are equal to the Fund's annualized net expense ratio of 0.90%, 1.76%, 1.67%, and 0.61% for Class A, Class B, Class C 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 | 2/28/13 15 Hypothetical Example for Comparison Purposes The table below provides information about hypothetical account values and hypothetical expenses based on the Fund's actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the Fund's actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. You may use this information to compare the ongoing costs of investing in the Fund and other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other funds. Please note that the expenses shown in the tables are meant to highlight your ongoing costs only and do not reflect any transaction costs, such as sales charges (loads) that are charged at the time of the transaction. Therefore, the table below is useful in comparing ongoing costs only and will not help you determine the relative total costs of owning different funds. In addition, if these transaction costs were included, your costs would have been higher. Expenses Paid on a $1,000 Investment in Pioneer Short Term Income Fund Based on a hypothetical 5% return per year before expenses, reflecting the period from September 1, 2012, through February 28, 2013. -------------------------------------------------------------------------------- Share Class A B C Y -------------------------------------------------------------------------------- Beginning Account $1,000.00 $1,000.00 $1,000.00 $1,000.00 Value on 9/1/12 -------------------------------------------------------------------------------- Ending Account $1,020.33 $1,016.07 $1,016.51 $1,021.77 Value (after expenses) on 2/28/13 -------------------------------------------------------------------------------- Expenses Paid $4.51 $8.80 $8.35 $3.06 During Period* -------------------------------------------------------------------------------- * Expenses are equal to the Fund's annualized net expense ratio of 0.90%, 1.76%, 1.67%, and 0.61% for Class A, Class B, Class C and Class Y shares, respectively, multiplied by the average account value over the period, multiplied by 181/365 (to reflect the one-half year period). 16 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 Schedule of Investments | 2/28/13 (unaudited) ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- ASSET BACKED SECURITIES -- 16.4% MATERIALS -- 5.2% Commodity Chemicals -- 0.3% 800,000 2.70 NR/A2 Navistar Financial Dealer Note Master Owner Trust II, Floating Rate Note, 10/25/16 (144A) $ 807,134 ---------------------------------------------------------------------------------------------------------- Diversified Metals & Mining -- 0.1% 285,889 NR/A1 BCMSC Trust 1998-A, 6.65%, 4/15/28 $ 297,838 ---------------------------------------------------------------------------------------------------------- Precious Metals & Minerals -- 0.6% 136,323 6.50 BB+/Baa2 ACE Securities Corp., Manufactured Housing Trust Series 2003-MH1, Floating Rate Note, 8/15/30 (144A) $ 137,584 1,402,837 0.65 AAA/A2 Lehman ABS Manufactured Housing Contract Trust 2002-A, Floating Rate Note, 6/15/33 1,367,809 -------------- $ 1,505,393 ---------------------------------------------------------------------------------------------------------- Steel -- 3.8% 240,000 0.60 CCC/Baa3 Accredited Mortgage Loan Trust 2005-2, Floating Rate Note, 7/25/35 $ 231,140 397,555 0.47 BB+/Baa3 Aegis Asset Backed Securities Trust 2005-5, Floating Rate Note, 12/25/35 374,167 605,050 0.56 AAA/Aaa Aegis Asset Backed Securities Trust Mortgage Pass-Through Certificates Series 2004-3, Floating Rate Note, 9/25/34 593,387 36,558 0.86 AA+/Aa2 Asset Backed Securities Corp., Home Equity, Floating Rate Note, 4/25/35 36,479 356,010 4.91 AA+/NR Bayview Financial Asset Trust 2003-A, Floating Rate Note, 2/25/33 (144A) 363,602 585,854 0.50 AA+/A1 Bayview Financial Mortgage Pass-Through Trust 2006-B, Floating Rate Note, 4/28/36 563,292 82,091 0.47 AA+/A1 Bayview Financial Mortgage Pass-Through Trust 2006-B, Floating Rate Note, 4/28/36 78,351 425,000 0.65 AA/Aa2 Bayview Financial Mortgage Pass-Through Trust Series 2005-B, Floating Rate Note, 4/28/39 417,005 300,000 1.25 AA+/A3 Bear Stearns Asset Backed Securities I Trust 2004-BO1, Floating Rate Note, 10/25/34 284,063 464,161 0.70 A+/Ba3 Bear Stearns Asset Backed Securities I Trust 2005-FR1, Floating Rate Note, 6/25/35 453,437 247,661 0.68 AA+/Aa2 Bear Stearns Asset Backed Securities I Trust 2005-HE6, Floating Rate Note, 6/25/35 241,630 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 17 Schedule of Investments | 2/28/13 (unaudited) (continued) ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Steel -- (continued) 281,627 0.70 AA+/NR Bear Stearns Asset Backed Securities I Trust 2005-HE8, Floating Rate Note, 8/25/35 $ 280,287 29,879 0.31 AA+/Baa1 Bear Stearns Asset Backed Securities I Trust 2006-HE10, Floating Rate Note, 12/25/36 29,822 946,724 0.60 AA+/Aa2 First NLC Trust 2005-2, Floating Rate Note, 9/25/35 921,686 649,106 0.98 AA+/Ba1 GSAA Home Equity Trust 2004-6, Floating Rate Note, 6/25/34 621,255 262,326 0.45 B+/B3 GSAA Home Equity Trust 2005-11, Floating Rate Note, 10/25/35 256,954 116,153 0.86 AA/A1 Home Equity Asset Trust 2005-3, Floating Rate Note, 8/25/35 113,065 222,287 0.61 AAA/Aaa Home Equity Asset Trust 2005-5, Floating Rate Note, 11/25/35 220,041 107,624 0.38 BBB+/A1 Home Equity Asset Trust 2006-3, Floating Rate Note, 7/25/36 106,924 123,047 0.39 AA+/Aa1 HSBC Home Equity Loan Trust USA 2007-2, Floating Rate Note, 7/20/36 120,451 283,484 NR/Baa1 Irwin Home Equity Loan Trust 2005-1, 5.32%, 6/25/35 (Step) 276,228 82,717 0.54 BB/A2 IXIS Real Estate Capital Trust 2005-HE4, Floating Rate Note, 2/25/36 80,242 1,022,151 0.43 BB+/A2 Mastr Asset Backed Securities Trust 2006-AB1, Floating Rate Note, 2/25/36 1,010,001 129,888 0.52 A+/Ba1 Morgan Stanley Home Equity Loan Trust 2005-4, Floating Rate Note, 9/25/35 124,849 162,497 0.55 AAA/Aaa New Century Home Equity Loan Trust Series 2005-1, Floating Rate Note, 3/25/35 157,999 843,517 0.50 AAA/Aa1 New Century Home Equity Loan Trust Series 2005-2, Floating Rate Note, 6/25/35 835,111 198,841 0.46 AA+/Aa3 Option One Mortgage Loan Trust 2005-4 Asset-Backed Certificates Series 2005-4, Floating Rate Note, 11/25/35 195,598 46,799 0.32 A+/Aa3 Option One Mortgage Loan Trust 2007-HL1, Floating Rate Note, 2/25/38 46,648 250,000 0.77 AAA/Aaa Penarth Master Issuer Plc, Floating Rate Note, 3/18/14 (144A) 250,022 157,538 0.64 AA+/A1 RASC Series 2005-KS7 Trust, Floating Rate Note, 8/25/35 153,343 204,373 0.98 AA/Baa3 Soundview Home Loan Trust 2005-3, Floating Rate Note, 6/25/35 202,039 23,289 0.43 AA+/A1 Specialty Underwriting & Residential Finance Trust Series 2005-BC4, Floating Rate Note, 9/25/36 23,269 The accompanying notes are an integral part of these financial statements. 18 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Steel -- (continued) 615,147 0.50 BBB+/B2 Specialty Underwriting & Residential Finance Trust Series 2006-BC1, Floating Rate Note, 12/25/36 $ 591,026 -------------- $ 10,253,413 ---------------------------------------------------------------------------------------------------------- Paper Products -- 0.4% 500,000 1.05 AAA/Aaa Gracechurch Card Funding Plc, Floating Rate Note, 5/15/19 (144A) $ 506,640 400,000 0.85 AAA/Aaa Penarth Master Issuer Plc, Floating Rate Note, 5/18/15 (144A) 399,956 -------------- $ 906,596 -------------- Total Materials $ 13,770,374 ---------------------------------------------------------------------------------------------------------- TRANSPORTATION -- 0.1% Railroads -- 0.1% 247,648 A/NR Trinity Rail Leasing LP, 2.266%, 1/15/43 (144A) $ 257,438 -------------- Total Transportation $ 257,438 ---------------------------------------------------------------------------------------------------------- AUTOMOBILES & COMPONENTS -- 1.1% Auto Parts & Equipment -- 0.2% CAD 528,710 AAA/NR Ford Auto Securitization Trust Series 2011-R1 Asset-Backed Notes, 2.431%, 11/15/14 (144A) $ 521,718 ---------------------------------------------------------------------------------------------------------- Automobile Manufacturers -- 0.9% 26,615 AAA/Aaa AmeriCredit Automobile Receivables Trust 2009-1, 9.79%, 4/15/14 $ 26,931 567,000 AA/Aa2 AmeriCredit Automobile Receivables Trust 2010-2, 6.24%, 6/8/16 609,508 150,000 A+/NR AmeriCredit Automobile Receivables Trust, 1.57%, 1/8/19 150,467 100,000 NR/Aa3 AmeriCredit Automobile Receivables Trust, 4.04%, 7/10/17 106,333 97,558 NR/Aaa BMW Vehicle Owner Trust 2011-A, 0.76%, 8/25/15 97,840 646,979 1.20 AA-/NR Hyundai Capital Auto Funding VIII, Ltd., Floating Rate Note, 9/20/16 (144A) 648,337 240,434 A+/NR Santander Drive Auto Receivables Trust 2011-S2, 3.35%, 6/15/17 (144A) 241,954 500,000 A/A1 Santander Drive Auto Receivables Trust 2012-1, 3.78%, 11/15/17 525,297 125,000 A/A1 Santander Drive Auto Receivables Trust 2012-5, 2.7%, 8/15/18 130,592 -------------- $ 2,537,259 -------------- Total Automobiles & Components $ 3,058,977 ---------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 19 Schedule of Investments | 2/28/13 (unaudited) (continued) ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- CONSUMER SERVICES -- 0.2% Hotels, Resorts & Cruise Lines -- 0.2% 292,008 A/NR Westgate Resorts 2012-2 LLC, 3.0%, 1/20/25 (144A) $ 294,563 228,512 A/NR Westgate Resorts LLC, 2.5%, 3/20/25 (144A) 228,869 -------------- $ 523,432 -------------- Total Consumer Services $ 523,432 ---------------------------------------------------------------------------------------------------------- BANKS -- 7.3% Diversified Banks -- 0.1% 118,890 0.58 AA+/NR Wells Fargo Home Equity Asset-Backed Securities 2005-3 Trust, Floating Rate Note, 12/25/35 $ 116,982 65,402 0.29 NR/Aa1 Wells Fargo Home Equity Asset-Backed Securities 2007-2 Trust, Floating Rate Note, 4/25/37 64,345 -------------- $ 181,327 ---------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- 7.2% 120,328 0.38 BB+/B3 ACE Securities Corp Home Equity Loan Trust Series 2006-ASAP2, Floating Rate Note, 3/25/36 $ 116,103 348,538 0.50 AA+/Aa1 Ameriquest Mortgage Securities, Inc., Asset-Backed Pass-Through Certificates Series 2004-R11, Floating Rate Note, 11/25/34 346,583 99,242 0.40 AA+/Aaa Ameriquest Mortgage Securities, Inc., Asset-Backed Pass-Through Certificates Series 2005-R6, Floating Rate Note, 8/25/35 96,641 194,923 1.20 AAA/Aa3 Amortizing Residential Collateral Trust 2004-1, Floating Rate Note, 10/25/34 192,211 340,188 0.75 AAA/NR ARI Fleet Lease Trust 2012-A, Floating Rate Note, 3/15/20 (144A) 341,287 425,894 NR/NR Ascentium Equipment Receivables LLC, 1.83%, 9/15/19 (144A) 426,017 369,350 0.83 AAA/Aaa Bayview Financial Acquisition Trust, Floating Rate Note, 5/28/44 364,225 270,077 0.79 AAA/Aaa Bayview Financial Acquisition Trust, Floating Rate Note, 8/28/44 264,329 370,517 4.64 AA+/Baa2 Bear Stearns Asset Backed Securities Trust 2003-SD2, Floating Rate Note, 6/25/43 365,948 136,820 AA/NR CarNow Auto Receivables Trust 2012-1, 2.09%, 1/15/15 (144A) 136,888 1,396,794 0.38 BBB-/Ba3 Carrington Mortgage Loan Trust Series 2006-OPT1, Floating Rate Note, 2/25/36 1,387,790 239,425 1.22 BBB-/Caa1 Citigroup Mortgage Loan Trust, Inc., Floating Rate Note, 11/25/34 226,065 376,066 0.61 AAA/A3 Citigroup Mortgage Loan Trust, Inc., Floating Rate Note, 7/25/35 375,908 The accompanying notes are an integral part of these financial statements. 20 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 37,099 1.10 A-/Baa1 Citigroup Mortgage Loan Trust, Inc., Floating Rate Note, 7/25/37 $ 37,018 61,247 1.00 AAA/Aa3 Citigroup Mortgage Loan Trust, Inc., Floating Rate Note, 8/25/35 61,248 140,579 0.57 AA+/A2 Countrywide Asset-Backed Certificates, Floating Rate Note, 1/25/36 140,036 52,479 5.68 BB/B2 Countrywide Asset-Backed Certificates, Floating Rate Note, 10/25/46 52,335 203,214 0.59 AAA/Aa3 Countrywide Asset-Backed Certificates, Floating Rate Note, 11/25/34 197,331 346,796 5.07 BB+/B2 Countrywide Asset-Backed Certificates, Floating Rate Note, 2/25/36 351,366 424,040 1.10 A+/Baa1 Countrywide Asset-Backed Certificates, Floating Rate Note, 5/25/35 417,677 196,000 0.31 BBB-/Ba3 Countrywide Asset-Backed Certificates, Floating Rate Note, 5/25/37 195,420 93,885 0.38 B-/B2 Countrywide Asset-Backed Certificates, Floating Rate Note, 6/25/36 93,261 756,293 0.64 A+/A2 Countrywide Asset-Backed Certificates, Floating Rate Note, 7/25/35 755,553 168,824 0.55 BB+/Ba2 Countrywide Asset-Backed Certificates, Floating Rate Note, 8/25/47 167,525 239,583 A/NR Cronos Containers Program, Ltd., 3.81%, 9/18/27 (144A) 249,008 550,000 1.10 B-/Caa3 Ellington Loan Acquisition Trust 2007-1, Floating Rate Note, 5/28/37 (144A) 518,869 460,229 4.14 AAA/Aaa Equity One Mortgage Pass-Through Trust 2004-1, Floating Rate Note, 4/25/34 470,939 191,011 AAA/NR First Investors Auto Owner Trust 2012-2, 1.47%, 5/15/18 (144A) 191,389 200,000 A/NR First Investors Auto Owner Trust, 2.02%, 1/15/19 (144A) 199,816 56,007 0.85 A/A2 GSAMP Trust 2005-HE2, Floating Rate Note, 3/25/35 54,815 450,000 AAA/NR HLSS Servicer Advance Receivables Backed Notes, 0.898%, 1/15/44 (144A) 450,270 200,000 A/NR HLSS Servicer Advance Receivables Backed Notes, 1.644%, 1/15/44 (144A) 200,400 250,000 AA/NR HLSS Servicer Advance Receivables Backed Notes, 1.744%, 1/16/46 (144A) 250,700 125,000 BBB/NR HLSS Servicer Advance Receivables Backed Notes, 2.487%, 1/15/44 (144A) 125,312 350,000 BBB/NR HLSS Servicer Advance Receivables Backed Notes, 4.94%, 10/15/45 (144A) 364,105 315,599 A+/B1 Home Equity Mortgage Trust, 5.821%, 4/25/35 (Step) 310,202 500,000 AAA/NR Honda Auto Receivables Owner Trust, 0.35%, 6/22/15 499,986 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 21 Schedule of Investments | 2/28/13 (unaudited) (continued) ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 195,000 NR/Aaa Leaf Receivables Funding 8 LLC, 1.55%, 11/15/17 (144A) $ 197,176 550,000 2.45 A+/Baa1 Madison Avenue Manufactured Housing Contract, Floating Rate Note, 3/25/32 537,793 448,905 0.50 A/NR Master Specialized Loan Trust, Floating Rate Note, 1/25/36 (144A) 417,061 252,124 0.40 BBB-/Baa1 Morgan Stanley ABS Capital I, Inc., Trust 2006-WMC1, Floating Rate Note, 12/25/35 248,822 550,000 AAA/NR Nationstar Agency Advance Funding Trust 2013-T1A, 0.997%, 2/15/45 (144A) 550,896 207,555 0.82 AA+/A3 Park Place Securities, Inc., Asset-Backed Pass-Through Certificates Series 2004-WCW2, Floating Rate Note, 10/25/34 207,150 386,309 0.57 BBB+/Ba3 Park Place Securities, Inc., Asset-Backed Pass-Through Certificates Series 2005-WHQ4, Floating Rate Note, 9/25/35 383,784 923,000 1.40 AAA/Aaa PFS Financing Corp., Floating Rate Note, 2/15/16 (144A) 930,367 761,886 BB-/Ba1 Popular ABS Mortgage Pass-Through Trust 2004-4, 5.169%, 9/25/34 (Step) 647,259 221,330 0.45 B/Ba3 RAAC Series 2006-RP2 Trust, Floating Rate Note, 2/25/37 (144A) 212,652 59,480 A/NR Santander Drive Auto Receivables Trust 2010-1, 1.89%, 5/15/17 (144A) 59,809 600,000 0.53 NR/Aaa Smart Trust/Australia, Floating Rate Note, 6/14/15 600,459 500,000 0.65 NR/Aaa Smart Trust/Australia, Floating Rate Note, 9/14/16 500,547 720,670 AA/NR SNAAC Auto Receivables Trust, 1.78%, 6/15/16 (144A) 725,160 364,213 0.46 BB+/NR Soundview Home Loan Trust 2005-OPT4, Floating Rate Note, 12/25/35 360,631 350,000 NR/NR Stanwich Mortgage Loan Trust, 2.981%, 2/16/43 (144A) 350,220 341,715 A/NR Store Master Funding LLC, 5.77%, 8/20/42 (144A) 360,823 21,490 BBB+/A2 Structured Asset Securities Corp., Mortgage Loan Trust 2005-2XS, 4.44%, 2/25/35 (Step) 21,453 450,519 BBB+/Ba2 Structured Asset Securities Corp., Mortgage Loan Trust 2005-2XS, 4.65%, 2/25/35 (Step) 461,985 32,389 0.25 A+/Aa1 Structured Asset Securities Corp., Mortgage Loan Trust 2007-BC1, Floating Rate Note, 2/25/37 32,279 177,069 A+/NR SVO 2012-A VOI Mortgage LLC, 2.0%, 9/20/29 (144A) 177,511 The accompanying notes are an integral part of these financial statements. 22 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 312,238 0.57 AA+/A2 Wachovia Mortgage Loan Trust Series 2005-WMC1, Floating Rate Note, 10/25/35 $ 307,070 -------------- $ 19,285,483 -------------- Total Banks $ 19,466,810 ---------------------------------------------------------------------------------------------------------- DIVERSIFIED FINANCIALS -- 2.5% Other Diversified Financial Services -- 1.0% 370,000 NR/Aaa BMW Vehicle Lease Trust, 0.4%, 1/20/15 $ 370,004 300,000 A/A1 Capital Auto Receivables Asset Trust 2013-1, 1.74%, 10/22/18 299,881 125,000 BBB/Baa2 Capital Auto Receivables Asset Trust 2013-1, 2.19%, 9/20/21 124,903 174,544 AA/NR Direct Capital Funding IV LLC, 1.673%, 12/20/17 (144A) 174,544 325,000 BBB/NR DT Auto Owner Trust 2011-1, 4.89%, 1/17/17 (144A) 328,888 137,500 0.45 BBB+/Baa3 GE Seaco Finance Srl, Floating Rate Note, 11/17/20 (144A) 135,658 110,189 0.37 BB+/Baa2 Home Equity Asset Trust 2006-4, Floating Rate Note, 8/25/36 108,030 13,977 BBB+/Ba1 JP Morgan Mortgage Acquisition Trust 2007-CH1, 5.453%, 11/25/36 (Step) 13,955 237,098 0.38 CCC/Caa1 RASC Series 2007-KS3 Trust, Floating Rate Note, 4/25/37 231,762 337,746 1.20 A+/Baa3 Sierra Timeshare 2007-2 Receivables Funding LLC, Floating Rate Note, 9/20/19 (144A) 334,843 500,000 A/NR Springleaf Funding Trust 2013-A, 2.58%, 9/15/21 (144A) 499,964 -------------- $ 2,622,432 ---------------------------------------------------------------------------------------------------------- Specialized Finance -- 0.4% 522,343 AAA/Aaa Conseco Finance, 7.55%, 4/15/32 (Step) $ 541,414 73,324 6.69 AAA/Aaa Conseco Finance, Floating Rate Note, 11/15/32 73,720 256,000 0.64 NR/Aaa GE Dealer Floorplan Master Note Trust, Floating Rate Note, 10/20/17 256,544 235,774 NR/A2 Hercules Capital Funding Trust 2012-1, 3.32%, 12/16/17 (144A) 236,805 -------------- $ 1,108,483 ---------------------------------------------------------------------------------------------------------- Consumer Finance -- 0.7% 314,352 A+/NR American Credit Acceptance Receivables Trust, 1.64%, 11/15/16 (144A) $ 314,462 282,848 NR/Aa3 California Republic Auto Receivables Trust 2012-1, 1.18%, 8/15/17 (144A) 282,848 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 23 Schedule of Investments | 2/28/13 (unaudited) (continued) ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Consumer Finance -- (continued) 235,417 A/NR Global SC Finance II SRL, 4.11%, 7/19/27 (144A) $ 247,017 350,000 0.26 AAA/Aaa MBNA Credit Card Master Note Trust, Floating Rate Note, 10/15/15 349,946 155,540 AA/Baa1 Residential Funding Mortgage Securities II Home Loan Trust, 5.77%, 4/25/28 (Step) 163,531 285,000 NR/Aaa Santander Drive Auto Receivables Trust 2011-2, 2.66%, 1/15/16 290,295 380,000 1.05 AAA/Aaa SLM Student Loan Trust 2004-10, Floating Rate Note, 4/27/26 (144A) 376,607 -------------- $ 2,024,706 ---------------------------------------------------------------------------------------------------------- Asset Management & Custody Banks -- 0.3% 476,787 0.60 B/Caa2 Southern Pacific Secured Asset Corp., Floating Rate Note, 3/25/28 $ 343,399 487,500 0.37 BBB/Baa2 Triton Container Finance LLC, Floating Rate Note, 11/26/21 (144A) 478,541 -------------- $ 821,940 ---------------------------------------------------------------------------------------------------------- Investment Banking & Brokerage -- 0.1% 200,000 0.65 NR/Aaa Chesapeake Funding LLC, Floating Rate Note, 5/7/24 (144A) $ 200,176 -------------- Total Diversified Financials $ 6,777,737 ---------------------------------------------------------------------------------------------------------- TOTAL ASSET BACKED SECURITIES (Cost $43,541,587) $ 43,854,768 ---------------------------------------------------------------------------------------------------------- COLLATERALIZED MORTGAGE OBLIGATIONS -- 30.8% BANKS -- 19.2% Thrifts & Mortgage Finance -- 19.2% 379,350 0.48 A+/Ba1 Adjustable Rate Mortgage Trust 2005-5, Floating Rate Note, 9/25/35 $ 348,952 250,455 0.65 CCC/NR Alternative Loan Trust 2003-14T1, Floating Rate Note, 8/25/18 234,936 82,480 0.75 A+/NR Alternative Loan Trust 2003-9T1, Floating Rate Note, 7/25/33 81,910 432,842 BB-/B2 Alternative Loan Trust 2003-J1, 4.75%, 10/25/33 442,442 230,106 0.65 BBB+/Ba1 Alternative Loan Trust 2004-18CB, Floating Rate Note, 9/25/34 228,183 346,165 BB+/Ba2 Alternative Loan Trust 2004-4CB, 4.25%, 4/25/34 348,500 98,244 5.75 NR/NR American General Mortgage Loan Trust 2009-1, Floating Rate Note, 9/25/48 (144A) 98,378 341,987 0.65 NR/A1 Banc of America Alternative Loan Trust 2003-10, Floating Rate Note, 12/25/33 328,862 The accompanying notes are an integral part of these financial statements. 24 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 185,283 NR/B3 Banc of America Alternative Loan Trust 2004-2, 5.5%, 3/25/19 $ 190,605 265,740 NR/B2 Banc of America Alternative Loan Trust 2004-4, 5.25%, 5/25/34 270,302 223,370 BBB+/NR Banc of America Funding 2003-3 Trust, 5.5%, 10/25/33 234,850 61,451 B+/B1 Banc of America Funding 2005-6 Trust, 5.75%, 10/25/35 61,799 653,463 0.41 A/NR Banc of America Funding 2010-R4 Trust, Floating Rate Note, 6/26/37 (144A) 647,018 650,000 1.30 A-/A3 Banc of America Large Loan Trust 2007-BMB1, Floating Rate Note, 8/15/29 (144A) 625,161 1,532,784 3.14 NR/Baa3 Banc of America Mortgage 2003-H Trust, Floating Rate Note, 9/25/33 1,537,082 1,888,548 NR/Caa2 Bayview Commercial Asset Trust, 3.89%, 9/25/37 (Step) (144A) 175,824 2,663,887 4.28 NR/Caa2 Bayview Commercial Asset Trust, Floating Rate Note, 7/25/37 (144A) 140,387 118,245 3.48 BBB+/Ba1 Bear Stearns ARM Trust 2004-9, Floating Rate Note, 11/25/34 118,682 150,000 5.21 NR/Baa2 Bear Stearns Commercial Mortgage Securities Trust 2005-PWR7, Floating Rate Note, 2/11/41 154,206 694,604 NR/NR Cendant Mortgage Corp., 6.25%, 3/25/32 (144A) 657,797 509,345 0.40 A+/Baa1 Chevy Chase Funding LLC Mortgage-Backed Certificates Series 2005-A, Floating Rate Note, 1/25/36 (144A) 428,964 805,860 A/NR CHL Mortgage Pass-Through Trust 2002-J4, 5.5%, 10/25/32 833,428 557,975 0.74 AA+/Baa1 CHL Mortgage Pass-Through Trust 2004-29, Floating Rate Note, 2/25/35 526,050 228,359 NR/Baa3 CHL Mortgage Pass-Through Trust 2004-9, 5.25%, 6/25/34 235,889 250,070 NR/Caa1 CHL Mortgage Pass-Through Trust 2005-19, 5.5%, 8/25/35 255,887 26,657 0.34 A+/Aaa Citigroup Commercial Mortgage Trust 2007-FL3A, Floating Rate Note, 4/15/22 (144A) 26,359 522,521 0.41 BBB-/Aa2 Citigroup Commercial Mortgage Trust 2007-FL3A, Floating Rate Note, 4/15/22 (144A) 502,571 222,339 NR/Aa2 Citigroup Mortgage Loan Trust, Inc., 7.0%, 9/25/33 230,210 220,837 5.50 CC/NR Citigroup Mortgage Loan Trust, Inc., Floating Rate Note, 11/25/35 27,325 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 25 Schedule of Investments | 2/28/13 (unaudited) (continued) ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 247,714 2.85 CC/NR Citigroup Mortgage Loan Trust, Inc., Floating Rate Note, 4/25/35 $ 176,994 180,289 0.64 BBB+/A2 CNL Commercial Mortgage Loan Trust 2003-2, Floating Rate Note, 10/25/30 (144A) 160,457 59,778 1.19 NR/WR Collateralized Mortgage Obligation Trust 44, Floating Rate Note, 7/1/18 60,399 494,209 0.30 AAA/Aaa COMM 2006-FL12 Mortgage Trust, Floating Rate Note, 12/15/20 (144A) 488,945 1,000,000 0.33 AA-/A1 COMM 2006-FL12 Mortgage Trust, Floating Rate Note, 12/15/20 (144A) 958,547 331,304 0.38 A+/A1 COMM 2007-FL14 Mortgage Trust, Floating Rate Note, 6/15/22 (144A) 327,013 30,267 NR/Aaa Commercial Mortgage Pass Through Certificate Series 2003-ML1, 4.767%, 3/12/39 30,269 597,741 2.14 AAA/NR Commercial Mortgage Pass Through Certificates, Floating Rate Note, 11/17/26 (144A) 606,280 53,684 1.45 AAA/NR Deutsche Mortgage Securities, Inc., REMIC Trust Series 2010-RS2, Floating Rate Note, 6/28/47 (144A) 54,490 146,121 0.57 AA+/Aa3 DSLA Mortgage Loan Trust 2004-AR3, Floating Rate Note, 7/19/44 138,107 200,000 1.31 AA-/NR Extended Stay America Trust, Floating Rate Note, 12/5/31 (144A) 200,018 63,910 2.59 BBB+/A1 First Horizon Mortgage Pass-Through Trust 2004-AR1, Floating Rate Note, 2/25/34 62,736 44,733 CCC/NR First Horizon Mortgage Pass-Through Trust 2006-1, 6.0%, 5/25/36 44,795 131,026 0.63 AA+/Aa2 GE Business Loan Trust 2003-1, Floating Rate Note, 4/15/31 (144A) 124,749 311,768 0.49 AA/Aa2 GE Business Loan Trust 2004-1, Floating Rate Note, 5/15/32 (144A) 301,024 148,682 0.37 A/Aa3 GE Business Loan Trust 2007-1, Floating Rate Note, 4/16/35 (144A) 136,470 377,469 NR/Aaa GE Capital Commercial Mortgage Corp., 5.145%, 7/10/37 380,728 445,000 5.34 NR/Aa3 GE Capital Commercial Mortgage Corp., Floating Rate Note, 7/10/37 (144A) 452,363 600,000 5.34 NR/Baa2 GE Capital Commercial Mortgage Corp., Floating Rate Note, 7/10/37 (144A) 604,898 500,000 5.15 BBB-/NR GE Capital Commercial Mortgage Corp., Floating Rate Note, 7/10/45 (144A) 502,109 250,000 5.31 BBB+/Baa2 GMAC Commercial Mortgage Securities, Inc., Series 2003-C1 Trust, Floating Rate Note, 5/10/36 (144A) 250,000 The accompanying notes are an integral part of these financial statements. 26 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 150,000 5.46 B+/NR GMAC Commercial Mortgage Securities, Inc., Series 2003-C2 Trust, Floating Rate Note, 5/10/40 (144A) $ 147,437 496,796 AAA/Aaa GMAC Commercial Mortgage Securities, Inc., Series 2003-C3 Trust, 5.023%, 4/10/40 506,477 400,000 1.65 NR/Aa3 GS Mortgage Securities Corp., II, Floating Rate Note, 11/8/29 (144A) 401,457 350,000 NR/NR GS Mortgage Securities Corp., II, 4.209%, 2/10/21 (144A) 353,500 500,000 1.26 AAA/Aaa GS Mortgage Securities Corp., II, Floating Rate Note, 3/6/20 (144A) 500,878 100,000 2.20 AA/NR GS Mortgage Securities Corp., II, Floating Rate Note, 3/6/20 (144A) 100,493 376,480 2.59 B+/NR GSR Mortgage Loan Trust 2003-9, Floating Rate Note, 8/25/33 379,738 418,932 3.06 A+/B1 GSR Mortgage Loan Trust 2004-7, Floating Rate Note, 6/25/34 422,202 231,626 5.25 BB-/NR GSR Mortgage Loan Trust 2005-AR4, Floating Rate Note, 7/25/35 228,659 483,826 0.55 AA+/Aa3 Homestar Mortgage Acceptance Corp., Floating Rate Note, 6/25/34 479,576 1,629,937 0.84 BBB/Ba3 Impac CMB Trust Series 2004-4, Floating Rate Note, 9/25/34 1,554,776 483,220 4.92 AAA/Aaa JP Morgan Chase Commercial Mortgage Securities Corp., Pass Through Certs Ser 2003-LN1, Floating Rate Note, 10/15/37 487,938 650,000 2.07 AA/Aa2 JP Morgan Chase Commercial Mortgage Securities Corp., Floating Rate Note, 10/15/25 (144A) 658,453 198,801 NR/Aaa JP Morgan Chase Commercial Mortgage Securities Trust 2006-CIBC15, 5.819%, 6/12/43 200,960 290,708 NR/Aaa JP Morgan Chase Commercial Mortgage Securities Trust 2006-CIBC17, 5.45%, 12/12/43 290,817 1,317,327 0.33 NR/Aa2 JP Morgan Chase Commercial Mortgage Securities Trust 2006-FL2, Floating Rate Note, 11/15/18 (144A) 1,299,436 212,191 0.56 NR/Ba1 JP Morgan Chase Commercial Mortgage Securities Trust 2006-FL2, Floating Rate Note, 11/15/18 (144A) 179,530 250,000 0.36 AA/Aa3 JP Morgan Chase Commercial Mortgage Securities Trust 2006-LDP9, Floating Rate Note, 5/15/47 248,218 475,000 5.73 AAA/Aaa JP Morgan Chase Commercial Mortgage Securities Trust 2007-CIBC19, Floating Rate Note, 2/12/49 485,693 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 27 Schedule of Investments | 2/28/13 (unaudited) (continued) ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 547,277 2.31 BBB/Baa1 JP Morgan Mortgage Trust 2003-A1, Floating Rate Note, 10/25/33 $ 556,905 453,861 2.52 AA+/Baa3 JP Morgan Mortgage Trust 2004-A1, Floating Rate Note, 2/25/34 468,638 76,244 2.58 BBB+/Ba1 JP Morgan Mortgage Trust 2005-A4, Floating Rate Note, 7/25/35 76,652 64,454 NR/Caa3 JP Morgan Mortgage Trust 2006-S3, 6.0%, 8/25/36 3,397 650,000 5.62 BBB+/NR LB-UBS Commercial Mortgage Trust 2002-C4, Floating Rate Note, 10/15/35 (144A) 648,932 247,027 AAA/Aaa LB-UBS Commercial Mortgage Trust 2004-C1, 4.568%, 1/15/31 253,852 500,000 AAA/Aaa LB-UBS Commercial Mortgage Trust 2004-C2, 4.367%, 3/15/36 514,487 120,852 AAA/Aaa LB-UBS Commercial Mortgage Trust 2005-C3, 4.664%, 7/15/30 122,997 175,412 6.16 AAA/Aaa LB-UBS Commercial Mortgage Trust 2008-C1, Floating Rate Note, 4/15/41 186,306 939,326 0.37 AA+/Aaa Lehman Brothers Floating Rate Commercial Mortgage Trust 2006-LLF C5, Floating Rate Note, 9/15/21 (144A) 928,141 80,367 0.90 BB/Aaa Lehman Brothers Floating Rate Commercial Mortgage Trust 2007-LLF C5, Floating Rate Note, 6/15/22 (144A) 79,697 268,680 0.43 A+/Aa2 Lehman Brothers Small Balance Commercial, Floating Rate Note, 4/25/31 (144A) 231,310 527,309 0.45 A+/Aa3 Lehman Brothers Small Balance Commercial, Floating Rate Note, 9/25/30 (144A) 460,025 339,476 0.72 BB/B2 Lehman Brothers Small Balance Commercial, Floating Rate Note, 9/25/30 (144A) 167,158 250,000 1.30 A+/B1 Master Adjustable Rate Mortgages Trust 2004-11, Floating Rate Note, 11/25/34 222,058 48,818 AAA/NR Master Alternative Loan Trust 2004-13, 4.5%, 1/25/15 48,934 164,553 0.60 AA+/NR Master Asset Securitization Trust 2003-6, Floating Rate Note, 7/25/18 162,701 218,683 6.62 A-/NR Master Seasoned Securitization Trust 2005-1, Floating Rate Note, 9/25/32 229,296 622,383 1.28 BBB+/Baa3 Merrill Lynch Mortgage Investors Trust Series MLCC 2003-A, Floating Rate Note, 3/25/28 613,613 208,200 2.40 A+/Baa3 Merrill Lynch Mortgage Investors Trust Series MLCC 2003-G, Floating Rate Note, 1/25/29 210,833 The accompanying notes are an integral part of these financial statements. 28 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 267,522 0.66 A+/A3 Merrill Lynch Mortgage Investors Trust Series MLCC 2004-A, Floating Rate Note, 4/25/29 $ 261,541 299,947 1.11 A+/Baa2 Merrill Lynch Mortgage Investors Trust Series MLCC 2004-G, Floating Rate Note, 1/25/30 290,640 223,861 2.44 BBB/B3 Merrill Lynch Mortgage Investors Trust Series MLCC 2005-2, Floating Rate Note, 10/25/35 221,656 138,276 5.29 NR/Aaa ML-CFC Commercial Mortgage Trust 2006-3, Floating Rate Note, 7/12/46 139,933 700,000 NR/NR Morgan Stanley Re-REMIC Trust 2010-R9, 5.0%, 11/26/36 (144A) 708,596 290,678 1.40 AAA/Aaa NorthStar 2012-1 Mortgage Trust, Floating Rate Note, 8/25/29 (144A) 290,375 171,416 0.45 BB+/B2 Opteum Mortgage Acceptance Corp., Asset Backed Pass-Through Certificates 2005-5, Floating Rate Note, 12/25/35 167,414 206,197 NR/A2 PHH Mortgage Capital LLC, 6.6%, 12/25/27 (Step) (144A) 201,767 295,000 A+/NR Prudential Commercial Mortgage Trust 2003-PWR1, 4.706%, 2/11/36 294,901 680,871 BB+/B2 RAAC Series 2004-SP2 Trust, 6.0%, 1/25/32 694,764 267,444 6.25 BBB+/NR RAMP Series 2004-SL4 Trust, Floating Rate Note, 5/25/18 273,419 166,404 1.60 B-/Ba1 RESI Finance LP, Floating Rate Note, 9/10/35 (144A) 146,701 1,885,213 0.60 BBB+/NR Residential Asset Securitization Trust 2003-A2, Floating Rate Note, 5/25/33 1,705,417 27,488 0.70 AA+/NR Residential Asset Securitization Trust 2003-A6, Floating Rate Note, 7/25/33 27,428 441,022 B/NR Residential Asset Securitization Trust 2004-A9, 5.75%, 12/25/34 451,510 408,015 CCC/NR Residential Asset Securitization Trust 2005-A9, 5.5%, 7/25/35 407,298 355,172 2.68 BBB+/B2 SASCO Mortgage Pass-through Certificates Series 2004-S4, Floating Rate Note, 12/25/34 361,502 280,566 0.82 AA+/Baa3 Sequoia Mortgage Trust 2003-5, Floating Rate Note, 9/20/33 277,257 209,742 0.52 A+/Baa3 Sequoia Mortgage Trust 2004-10, Floating Rate Note, 11/20/34 206,372 870,099 0.47 A/Baa1 Sequoia Mortgage Trust 2004-12, Floating Rate Note, 1/20/35 811,883 304,991 0.80 AA/A3 Sequoia Mortgage Trust 2004-12, Floating Rate Note, 1/20/35 288,265 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 29 Schedule of Investments | 2/28/13 (unaudited) (continued) ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 370,164 1.88 AA+/Baa3 Sequoia Mortgage Trust 2004-7, Floating Rate Note, 8/20/34 $ 369,943 541,758 0.74 AA+/B1 Sequoia Mortgage Trust 2005-1, Floating Rate Note, 2/20/35 537,445 116,747 NR/Baa3 SMA Issuer I LLC, 3.5%, 8/20/25 (144A) 117,352 371,206 2.22 AAA/NR Springleaf Mortgage Loan Trust 2012-2, Floating Rate Note, 10/25/57 (144A) 375,586 689,498 3.74 CCC/Caa3 Structured Asset Mortgage Investments II Trust 2005-AR2, Floating Rate Note, 5/25/45 486,410 548,355 0.75 AA+/A1 Structured Asset Mortgage Investments II Trust 2005-F1, Floating Rate Note, 8/26/35 544,859 531,037 0.70 A+/Baa3 Structured Asset Securities Corp., Mortgage Pass-Through Certificates Series 2003-35, Floating Rate Note, 12/25/33 515,631 284,501 2.89 A+/Baa3 Structured Asset Securities Corp., Mortgage Certificates Series 2003-31A, Floating Rate Note, 10/25/33 289,853 1,218,273 2.60 A+/Baa3 Structured Asset Securities Corp Mortgage Pass-Through Certificates Series 2003-24A, Floating Rate Note, 7/25/33 1,195,451 266,422 0.85 NR/NR Structured Asset Securities Corp Reverse Mortgage Loan Trust 2002-RM1, Floating Rate Note, 10/25/37 (144A) 263,591 398,435 1.78 AAA/A1 Thornburg Mortgage Securities Trust 2004-1, Floating Rate Note, 3/25/44 401,477 1,459,791 0.94 BBB+/Baa3 Thornburg Mortgage Securities Trust 2004-3, Floating Rate Note, 9/25/44 1,431,170 328,556 1.86 AA+/Ba1 Thornburg Mortgage Securities Trust Class II2A, Floating Rate Note, 3/25/44 327,710 255,283 4.08 AAA/Ba1 Thornburg Mortgage Securities Trust Class II4A, Floating Rate Note, 3/25/44 256,190 525,000 AAA/Aa1 Timberstar Trust, 5.668%, 10/15/36 (144A) 601,011 404,425 0.78 BB+/Aaa UBS Commercial Mortgage Trust 2007-FL1, Floating Rate Note, 7/15/24 (144A) 397,395 78,410,257 0.02 AAA/Aaa Wachovia Bank Commercial Mortgage Trust Series 2006-C26, Floating Rate Note, 6/15/45 18,818 500,000 5.61 AA-/NR Wachovia Commercial Mortgage Securities, Inc., Commercial Mortgage Pass-Through Certificates Series 03-C4, Floating Rate Note, 4/15/35 (144A) 499,274 650,000 5.30 BBB/NR WaMu Commercial Mortgage Securities Trust, Floating Rate Note, 5/25/36 (144A) 667,938 990,979 AA+/NR WaMu Mortgage Pass Through Certificates, 5.0%, 10/25/18 1,022,850 The accompanying notes are an integral part of these financial statements. 30 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 241,943 AA+/Baa3 Wells Fargo Mortgage Backed Securities 2003-15 Trust, 4.75%, 12/25/18 $ 249,138 463,284 5.00 NR/Ba2 Wells Fargo Mortgage Backed Securities 2005-AR6 Trust, Floating Rate Note, 4/25/35 473,037 72,007 AA+/A1 Wells Fargo Mortgage Backed Securities 2006-16 Trust, 5.0%, 11/25/36 74,639 633,152 NR/Caa1 Wells Fargo Mortgage Backed Securities 2006-2 Trust, 5.75%, 3/25/36 636,264 -------------- $ 51,147,791 -------------- Total Banks $ 51,147,791 ---------------------------------------------------------------------------------------------------------- DIVERSIFIED FINANCIALS -- 3.2% Other Diversified Financial Services -- 2.6% 210,000 A+/Baa2 American Tower Trust, 5.957%, 4/15/37 (144A) $ 213,447 275,391 3.13 AA+/NR Banc of America Mortgage 2003-F Trust, Floating Rate Note, 7/25/33 278,089 27,555 BB+/NR Banc of America Mortgage Trust 2004-7, 4.5%, 8/25/19 28,010 139,971 0.94 AA+/Baa1 Bear Stearns ALT-A Trust 2004-13, Floating Rate Note, 11/25/34 138,012 26,993 NR/Aaa Commercial Mortgage Pass-Through Certificates Series 2007-C1, 5.268%, 2/15/40 26,999 180,723 0.32 BBB+/Aaa Commercial Mortgage Pass-Through Certificates Series 2007-TFL1, Floating Rate Note, 2/15/22 (144A) 176,809 71,231 AAA/Aaa Commercial Mortgage Trust 2003-C1, 4.111%, 7/5/35 71,313 600,000 4.09 NR/NR CSMC Series 2010-16, Floating Rate Note, 6/25/50 (144A) 589,135 240,874 0.40 BB+/Baa2 Impac Secured Assets Trust 2006-5, Floating Rate Note, 12/25/36 220,662 148,447 2.55 BBB+/NR Merrill Lynch Mortgage Investors Trust Series MLMI 2005-A2, Floating Rate Note, 2/25/35 150,168 254,340 2.55 A+/NR Merrill Lynch Mortgage Investors Trust Series MLMI 2005-A2, Floating Rate Note, 2/25/35 255,904 250,000 0.90 BBB+/A3 Morgan Stanley Capital I, Inc., Class C, Floating Rate Note, 12/15/20 (144A) 233,000 215,953 NR/Baa3 ORES NPL LLC, 4.0%, 9/25/44 (144A) 216,383 440,017 0.75 NR/Baa3 RALI Series 2002-QS16 Trust, Floating Rate Note, 10/25/17 416,261 950,000 AAA/Baa3 RALI Series 2003-QR24 Trust, 4.0%, 7/25/33 945,678 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 31 Schedule of Investments | 2/28/13 (unaudited) (continued) ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Other Diversified Financial Services -- (continued) 66,416 NR/Ba1 RALI Series 2003-QS14 Trust, 5.0%, 7/25/18 $ 67,876 250,000 BB+/Ba3 RALI Series 2003-QS15 Trust, 5.5%, 8/25/33 258,253 325,000 BBB/Baa3 RALI Series 2003-QS17 Trust, 5.5%, 9/25/33 334,272 921,785 BBB+/Ba1 RALI Series 2004-QS1 Trust, 4.25%, 1/25/34 933,402 198,259 0.75 BBB+/Ba1 RALI Series 2004-QS1 Trust, Floating Rate Note, 1/25/34 190,647 304,575 NR/B3 RALI Series 2004-QS16 Trust, 5.5%, 12/25/34 300,206 210,456 BB+/Ba3 RALI Series 2004-QS5 Trust, 4.75%, 4/25/34 218,823 217,164 3.12 BB+/Ba2 Structured Adjustable Rate Mortgage Loan Trust Class 1A1, Floating Rate Note, 3/25/34 212,019 69,272 0.94 AAA/Aa1 Structured Adjustable Rate Mortgage Loan Trust, Floating Rate Note, 1/25/35 68,945 406,160 2.73 NR/NR Vericrest Opportunity Loan Transferee, Floating Rate Note, 11/25/60 (144A) 407,939 -------------- $ 6,952,252 ---------------------------------------------------------------------------------------------------------- Specialized Finance -- 0.3% 23,111 0.30 A/Aaa IndyMac INDX Mortgage Loan Trust 2007-FLX1, Floating Rate Note, 2/25/37 $ 23,088 700,000 1.70 AAA/Aaa Permanent Master Issuer Plc, Floating Rate Note, 7/15/42 (144A) 707,180 -------------- $ 730,268 ---------------------------------------------------------------------------------------------------------- Consumer Finance -- 0.1% 273,554 4.54 AA+/Baa3 GMACM Mortgage Loan Trust 2003-AR1, Floating Rate Note, 10/19/33 $ 282,601 ---------------------------------------------------------------------------------------------------------- Asset Management & Custody Banks -- 0.0%+ 120,143 2.87 NR/NR Jefferies & Co., Inc., Floating Rate Note, 5/26/37 (144A) $ 120,543 ---------------------------------------------------------------------------------------------------------- Investment Banking & Brokerage -- 0.2% 460,000 NR/A3 Morgan Stanley Dean Witter Capital I Trust 2001-TOP3, 6.79%, 7/15/33 $ 470,252 -------------- Total Diversified Financials $ 8,555,916 ---------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 32 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- REAL ESTATE -- 1.2% Mortgage REIT -- 1.2% 703,256 AAA/Aaa American Home Mortgage Investment Trust 2004-3, 5.01%, 10/25/34 (Step) $ 728,496 290,916 2.46 AA+/Ba1 American Home Mortgage Investment Trust 2005-1, Floating Rate Note, 6/25/45 289,054 115,409 BBB/NR Credit Suisse First Boston Mortgage Securities Corp., 5.25%, 10/25/19 117,196 71,613 B+/NR Credit Suisse First Boston Mortgage Securities Corp., 5.5%, 6/25/33 71,488 776,521 NR/Aaa Credit Suisse First Boston Mortgage Securities Corp., 7.13%, 11/15/30 781,639 345,849 BBB+/Baa3 Credit Suisse First Boston Mortgage Securities Corp., 7.5%, 5/25/32 358,326 114,078 2.80 BBB+/Ba1 Credit Suisse First Boston Mortgage Securities Corp., Floating Rate Note, 11/25/33 112,210 171,268 4.90 AAA/NR Credit Suisse First Boston Mortgage Securities Corp., Floating Rate Note, 12/15/36 173,425 141,151 1.55 AA+/A3 Credit Suisse First Boston Mortgage Securities Corp., Floating Rate Note, 12/25/33 135,492 130,111 1.70 NR/WR Credit Suisse First Boston Mortgage Securities Corp., Floating Rate Note, 8/25/33 124,202 750,000 6.45 D/Caa2 Credit Suisse First Boston Mortgage Securities Corp., Floating Rate Note, 9/15/34 (144A) 356,708 -------------- $ 3,248,236 -------------- Total Real Estate $ 3,248,236 ---------------------------------------------------------------------------------------------------------- GOVERNMENT -- 7.2% 86,529 NR/NR Fannie Mae Benchmark REMIC, 5.45%, 12/25/20 $ 87,955 4,250,829 3.74 NR/Aa1 Fannie Mae Grantor Trust 2001-T1, Floating Rate Note, 10/25/40 4,088,132 1,147,181 3.38 NR/NR Fannie Mae Grantor Trust 2004-T2, Floating Rate Note, 7/25/43 1,229,541 369,801 NR/NR Fannie Mae REMICS, 3.0%, 1/25/21 384,306 311,037 NR/NR Fannie Mae REMICS, 4.0%, 6/25/37 317,001 50,239 NR/NR Fannie Mae REMICS, 5.0%, 9/25/39 52,077 148,173 NR/NR Fannie Mae REMICS, 5.5%, 10/25/32 149,456 18,213 NR/NR Fannie Mae REMICS, 5.69%, 1/25/32 18,326 329,468 NR/NR Fannie Mae REMICS, 6.0%, 3/25/35 347,031 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 33 Schedule of Investments | 2/28/13 (unaudited) (continued) ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Government -- (continued) 179,245 NR/NR Fannie Mae REMICS, 6.0%, 6/25/29 $ 201,874 842,644 1.07 NR/NR Fannie Mae REMICS, Floating Rate Note, 1/25/24 847,136 191,000 0.40 NR/NR Fannie Mae REMICS, Floating Rate Note, 10/27/37 190,021 1,087,979 0.50 NR/NR Fannie Mae REMICS, Floating Rate Note, 12/25/42 1,090,376 149,071 0.51 NR/NR Fannie Mae REMICS, Floating Rate Note, 2/25/35 149,375 123,228 0.60 NR/NR Fannie Mae REMICS, Floating Rate Note, 4/25/34 123,858 582,753 0.75 NR/NR Fannie Mae REMICS, Floating Rate Note, 5/25/40 586,055 228,551 0.50 NR/NR Fannie Mae REMICS, Floating Rate Note, 7/25/35 228,669 1,119,871 2.79 NR/NR Fannie Mae Trust 2003-W2, Floating Rate Note, 7/25/42 1,109,310 291,544 2.75 NR/NR Fannie Mae Trust 2005-W3, Floating Rate Note, 4/25/45 300,977 312,257 2.29 NR/NR Fannie Mae Trust 2005-W4, Floating Rate Note, 6/25/35 324,571 158,321 NR/NR Freddie Mac REMICS, 4.0%, 12/15/22 161,424 304,714 NR/Aa1 Freddie Mac REMICS, 4.0%, 6/15/22 308,559 11,392 NR/NR Freddie Mac REMICS, 4.5%, 8/15/17 11,405 92,854 NR/NR Freddie Mac REMICS, 5.0%, 10/15/33 92,969 333,646 NR/NR Freddie Mac REMICS, 5.0%, 6/15/34 343,439 251,620 NR/NR Freddie Mac REMICS, 5.5%, 10/15/35 262,654 22,524 NR/NR Freddie Mac REMICS, 5.5%, 3/15/32 22,803 109,704 NR/NR Freddie Mac REMICS, 5.5%, 3/15/33 111,261 306,780 NR/NR Freddie Mac REMICS, 6.0%, 4/15/36 307,820 132,744 0.50 NR/NR Freddie Mac REMICS, Floating Rate Note, 1/15/36 133,093 459,720 0.65 NR/NR Freddie Mac REMICS, Floating Rate Note, 1/15/41 462,250 192,757 0.55 NR/NR Freddie Mac REMICS, Floating Rate Note, 11/15/36 193,288 132,807 0.45 NR/NR Freddie Mac REMICS, Floating Rate Note, 11/15/36 132,816 297,129 NR/NR Government National Mortgage Association, 3.0%, 4/20/41 311,569 30,485 NR/Aa1 Government National Mortgage Association, 4.009%, 5/16/37 30,540 259,942 NR/Aa1 Government National Mortgage Association, 4.549%, 6/16/28 263,810 The accompanying notes are an integral part of these financial statements. 34 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Government -- (continued) 1,107,613 NR/NR Government National Mortgage Association, 5.0%, 1/20/16 $ 1,153,576 218,198 NR/NR Government National Mortgage Association, 5.0%, 4/20/36 234,959 858,890 0.65 NR/NR Government National Mortgage Association, Floating Rate Note, 1/20/34 860,079 3,078,514 1.69 NR/NR Government National Mortgage Association, Floating Rate Note, 10/16/43 207,830 12,456,020 0.56 NR/NR Government National Mortgage Association, Floating Rate Note, 11/16/51 485,448 12,097,574 1.32 AAA/Aa1 Government National Mortgage Association, Floating Rate Note, 2/16/52 582,317 1,977,433 1.03 NR/NR Government National Mortgage Association, Floating Rate Note, 2/16/53 173,557 3,441,631 1.18 NR/NR Government National Mortgage Association, Floating Rate Note, 3/16/51 143,912 1,186,467 1.05 NR/NR Government National Mortgage Association, Floating Rate Note, 3/16/53 101,658 1,972,834 1.10 NR/NR Government National Mortgage Association, Floating Rate Note, 8/16/52 156,781 1,779,177 1.07 NR/NR Government National Mortgage Association, Floating Rate Note, 9/16/52 161,106 -------------- $ 19,236,970 -------------- Total Government $ 19,236,970 ---------------------------------------------------------------------------------------------------------- TOTAL COLLATERALIZED MORTGAGE OBLIGATIONS (Cost $84,067,786) $ 82,188,913 ---------------------------------------------------------------------------------------------------------- CORPORATE BONDS -- 29.0% ENERGY -- 1.7% Oil & Gas Equipment & Services -- 0.3% 739,000 BBB-/Baa2 Weatherford International, Ltd., Bermuda, 5.15%, 3/15/13 $ 739,824 ---------------------------------------------------------------------------------------------------------- Integrated Oil & Gas -- 0.6% 700,000 A/A1 ConocoPhillips Co., 1.05%, 12/15/17 $ 698,307 940,000 0.68 AA-/Aa1 Total Capital Canada, Ltd., Floating Rate Note, 1/15/16 944,284 -------------- $ 1,642,591 ---------------------------------------------------------------------------------------------------------- Oil & Gas Exploration & Production -- 0.3% 250,000 A/Aa3 Ras Laffan Liquefied Natural Gas Co., Ltd., III, 5.5%, 9/30/14 (144A) $ 266,250 500,000 BBB-/Baa2 TNK-BP Finance SA, 7.5%, 3/13/13 (144A) 500,650 -------------- $ 766,900 ---------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 35 Schedule of Investments | 2/28/13 (unaudited) (continued) ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Oil & Gas Storage & Transportation -- 0.5% 650,000 A-/A3 TransCanada PipeLines, Ltd., 0.75%, 1/15/16 $ 649,668 750,000 BBB/Baa2 Williams Partners LP, 3.8%, 2/15/15 791,260 -------------- $ 1,440,928 -------------- Total Energy $ 4,590,243 ---------------------------------------------------------------------------------------------------------- MATERIALS -- 0.7% Industrial Gases -- 0.2% 500,000 BBB/Baa2 Airgas, Inc., 2.85%, 10/1/13 $ 506,306 ---------------------------------------------------------------------------------------------------------- Specialty Chemicals -- 0.2% 536,000 BBB/Baa2 Cytec Industries, Inc., 4.6%, 7/1/13 $ 540,629 ---------------------------------------------------------------------------------------------------------- Construction Materials -- 0.1% 360,000 BBB+/Baa2 CRH America, Inc., 5.3%, 10/15/13 $ 369,415 ---------------------------------------------------------------------------------------------------------- Gold -- 0.2% 500,000 BBB+/Baa1 Barrick Gold Corp., 1.75%, 5/30/14 $ 506,647 -------------- Total Materials $ 1,922,997 ---------------------------------------------------------------------------------------------------------- CAPITAL GOODS -- 1.1% Aerospace & Defense -- 0.5% 360,000 BB/Ba2 Bombardier, Inc., 4.25%, 1/15/16 (144A) $ 373,500 500,000 A-/A2 Precision Castparts Corp., 1.25%, 1/15/18 499,949 500,000 A/A2 United Technologies Corp., 1.2%, 6/1/15 507,356 -------------- $ 1,380,805 ---------------------------------------------------------------------------------------------------------- Industrial Conglomerates -- 0.2% 500,000 AA+/Aa3 General Electric Co., 0.85%, 10/9/15 $ 501,564 ---------------------------------------------------------------------------------------------------------- Trading Companies & Distributors -- 0.4% 1,000,000 BBB/Baa2 Glencore Funding LLC, 6.0%, 4/15/14 (144A) $ 1,048,950 -------------- Total Capital Goods $ 2,931,319 ---------------------------------------------------------------------------------------------------------- AUTOMOBILES & COMPONENTS -- 0.9% Auto Parts & Equipment -- 0.3% 725,000 0.71 BBB+/Baa1 Johnson Controls, Inc., Floating Rate Note, 2/4/14 $ 727,008 ---------------------------------------------------------------------------------------------------------- Automobile Manufacturers -- 0.6% 1,000,000 BBB+/Baa1 Hyundai Motor Manufacturing Czech sro, 4.5%, 4/15/15 (144A) $ 1,063,433 100,000 BBB+/A3 Nissan Motor Acceptance Corp., 4.5%, 1/30/15 (144A) 106,564 The accompanying notes are an integral part of these financial statements. 36 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Automobile Manufacturers -- (continued) 500,000 A-/A3 Volkswagen International Finance NV, 1.6%, 11/20/17 (144A) $ 501,988 -------------- $ 1,671,985 -------------- Total Automobiles & Components $ 2,398,993 ---------------------------------------------------------------------------------------------------------- MEDIA -- 0.3% Broadcasting -- 0.3% 750,000 BBB/Baa2 Discovery Communications LLC, 3.7%, 6/1/15 $ 796,642 -------------- Total Media $ 796,642 ---------------------------------------------------------------------------------------------------------- FOOD, BEVERAGE & TOBACCO -- 0.3% Brewers -- 0.2% 500,000 BBB+/Baa1 SABMiller Holdings, Inc., 1.85%, 1/15/15 (144A) $ 508,764 ---------------------------------------------------------------------------------------------------------- Packaged Foods & Meats -- 0.1% 250,000 0.60 BBB+/A2 Campbell Soup Co., Floating Rate Note, 8/1/14 $ 250,728 -------------- Total Food, Beverage & Tobacco $ 759,492 ---------------------------------------------------------------------------------------------------------- HEALTH CARE EQUIPMENT & SERVICES -- 0.8% Health Care Equipment -- 0.2% 510,000 A/Baa1 St Jude Medical, Inc., 2.5%, 1/15/16 $ 529,642 ---------------------------------------------------------------------------------------------------------- Health Care Distributors -- 0.2% 500,000 A-/Baa2 Cardinal Health, Inc., 4.0%, 6/15/15 $ 534,886 ---------------------------------------------------------------------------------------------------------- Health Care Services -- 0.4% 1,000,000 BBB+/Baa3 Express Scripts Holding Co., 3.125%, 5/15/16 $ 1,055,366 -------------- Total Health Care Equipment & Services $ 2,119,894 ---------------------------------------------------------------------------------------------------------- PHARMACEUTICALS, BIOTECHNOLOGY & LIFE SCIENCES -- 0.9% Pharmaceuticals -- 0.2% 500,000 BBB-/Baa2 Zoetis, Inc., 1.15%, 2/1/16 (144A) $ 501,454 ---------------------------------------------------------------------------------------------------------- Life Sciences Tools & Services -- 0.7% 500,000 BBB+/Baa2 Agilent Technologies, Inc., 2.5%, 7/15/13 $ 503,696 620,000 BBB+/NR Agilent Technologies, Inc., 5.5%, 9/14/15 687,125 750,000 BBB+/Baa3 Life Technologies Corp., 3.375%, 3/1/13 750,000 -------------- $ 1,940,821 -------------- Total Pharmaceuticals, Biotechnology & Life Sciences $ 2,442,275 ---------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 37 Schedule of Investments | 2/28/13 (unaudited) (continued) ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- BANKS -- 5.5% Diversified Banks -- 3.2% 500,000 1.66 A/NR Abbey National Treasury Services Plc London, Floating Rate Note, 6/10/13 $ 500,932 500,000 A/A2 ABN AMRO Bank NV, 1.375%, 1/22/16 (144A) 500,359 500,000 A+/Aa3 Bank of Montreal, Ltd., 0.8%, 11/6/15 500,817 500,000 BBB-/Baa3 BBVA US Senior SAU, 3.25%, 5/16/14 504,750 500,000 A+/Aa3 Export-Import Bank of Korea, Ltd., 1.25%, 11/20/15 500,822 1,700,000 1.10 AA-/Aa3 HSBC Bank Plc, Floating Rate Note, 1/17/14 (144A) 1,711,082 1,000,000 0.94 AA-/Aa3 HSBC Bank Plc, Floating Rate Note, 8/12/13 (144A) 1,002,580 500,000 BBB+/Baa2 Intesa Sanpaolo S.p.A., 3.125%, 1/15/16 493,344 500,000 2.69 BBB+/Baa2 Intesa Sanpaolo S.p.A., Floating Rate Note, 2/24/14 (144A) 503,140 500,000 A+/A2 Standard Chartered Plc, 3.85%, 4/27/15 (144A) 528,540 500,000 A/Aa3 The Korea Development Bank, Ltd. 1.0%, 1/22/16 498,049 820,000 A/A3 Wachovia Corp., 5.25%, 8/1/14 870,560 350,000 2.07 A+/A2 Wachovia Corp., Floating Rate Note, 5/1/13 350,944 -------------- $ 8,465,919 ---------------------------------------------------------------------------------------------------------- Regional Banks -- 1.8% 103,000 A-/A2 BB&T Corp., 1.6%, 8/15/17 $ 104,340 500,000 A-/A2 BB&T Corp., 5.7%, 4/30/14 529,737 500,000 0.73 BBB-/Baa2 Fifth Third Bancorp, Floating Rate Note, 12/20/16 491,119 1,000,000 A-/A3 KeyBank NA Cleveland Ohio, 1.65%, 2/1/18 1,010,287 275,000 BBB+/Baa1 KeyBank NA Cleveland Ohio, 5.8%, 7/1/14 293,431 500,000 BBB+/Baa1 KeyCorp, 3.75%, 8/13/15 534,448 965,000 BBB+/Baa1 KeyCorp, 6.5%, 5/14/13 976,158 275,000 8.25 BBB/Baa3 PNC Financial Services Group, Inc., Floating Rate Note, 5/29/49 (Perpetual) 277,436 500,000 BBB/Baa1 SunTrust Banks, Inc., 3.5%, 1/20/17 538,051 -------------- $ 4,755,007 ---------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- 0.5% 325,000 BBB-/Baa2 Astoria Financial Corp., 5.0%, 6/19/17 $ 345,839 500,000 BBB/Baa2 Santander Holdings USA, Inc. Pennsylvania, 3.0%, 9/24/15 513,664 The accompanying notes are an integral part of these financial statements. 38 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- (continued) 500,000 0.76 AAA/Aaa Swedbank Hypotek AB, Floating Rate Note, 3/28/14 (144A) $ 501,910 -------------- $ 1,361,413 -------------- Total Banks $ 14,582,339 ---------------------------------------------------------------------------------------------------------- DIVERSIFIED FINANCIALS -- 9.0% Other Diversified Financial Services -- 5.2% 500,000 A-/Baa2 Bank of America Corp., 3.7%, 9/1/15 $ 527,806 250,000 6.50 BB+/NR Caelus Re II, Ltd., Floating Rate Note, 5/24/13 (Cat Bond) (144A) 252,150 250,000 0.00 NR/NR Caelus Re, Ltd., Floating Rate Note, 3/7/16 (Cat Bond) (144A) 250,000 1,000,000 BBB+/Baa3 Citigroup, Inc., 5.0%, 9/15/14 1,051,917 1,095,000 A-/Baa2 Citigroup, Inc., 5.5%, 4/11/13 1,101,363 375,000 10.25 BB-/NR Compass Re, Ltd., Floating Rate Note, 1/8/15 (Cat Bond) (144A) 383,212 250,000 6.60 BB-/NR Embarcadero Reinsurance, Ltd., Floating Rate Note, 8/4/14 (Cat Bond) (144A) 253,250 485,000 AA+/A1 General Electric Capital Corp., 1.625%, 7/2/15 493,543 1,000,000 AA+/A1 General Electric Capital Corp., 1.875%, 9/16/13 1,008,274 1,000,000 1.14 AA+/A1 General Electric Capital Corp., Floating Rate Note, 12/20/13 1,005,090 500,000 1.00 AA+/A1 General Electric Capital Corp., Floating Rate Note, 4/24/14 503,645 500,000 0.94 AA+/A1 General Electric Capital Corp., Floating Rate Note, 4/7/14 503,262 500,000 1.38 AA+/A1 General Electric Capital Corp., Floating Rate Note, 8/1/17 502,083 1,000,000 6.20 BB-/NR Ibis Re, Ltd., Floating Rate Note, 5/3/13 (Cat Bond) (144A) 1,005,100 500,000 4.00 A/A2 JPMorgan Chase & Co., Floating Rate Note, 2/25/21 518,150 500,000 6.00 BB/NR Lodestone Re, Ltd., Floating Rate Note, 1/8/14 (Cat Bond) (144A) 500,450 500,000 7.25 BB/NR Lodestone Re, Ltd., Floating Rate Note, 1/8/14 (Cat Bond) (144A) 503,850 500,000 6.25 BB/NR Lodestone Re, Ltd., Floating Rate Note, 5/17/13 (Cat Bond) (144A) 502,450 500,000 8.25 BB-/NR Lodestone Re, Ltd., Floating Rate Note, 5/17/13 (Cat Bond) (144A) 504,050 250,000 7.50 BB-/NR Queen Street II Capital, Ltd., Floating Rate Note, 4/9/14 (Cat Bond) (144A) 252,550 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 39 Schedule of Investments | 2/28/13 (unaudited) (continued) ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Other Diversified Financial Services -- (continued) 250,000 6.25 BB/NR Residential Reinsurance 2010, Ltd., Floating Rate Note, 6/6/13 (Cat Bond) (144A) $ 252,650 500,000 6.60 BB/NR Residential Reinsurance 2010, Ltd., Floating Rate Note, 6/6/13 (Cat Bond) (144A) 505,750 250,000 9.00 BB-/NR Residential Reinsurance 2011, Ltd., Floating Rate Note, 6/6/15 (Cat Bond) (144A) 261,475 250,000 7.00 BB/NR Shore Re, Ltd., Floating Rate Note, 7/8/13 (Cat Bond) (144A) 253,450 250,000 3.10 BBB-/NR Vita Capital IV, Ltd., Floating Rate Note, 1/15/16 (Cat Bond) (144A) 252,000 750,000 2.90 BBB-/NR Vita Capital V, Ltd., Floating Rate Note, 1/15/17 (Cat Bond) (144A) 754,350 -------------- $ 13,901,870 ---------------------------------------------------------------------------------------------------------- Specialized Finance -- 0.3% 175,000 BBB+/Baa1 Harley-Davidson Financial Services, Inc., 3.875%, 3/15/16 (144A) $ 188,184 500,000 A/A2 National Rural Utilities Cooperative Finance Corp., 5.4%, 10/15/13 512,212 150,000 A+/A3 NYSE Euronext, 2.0%, 10/5/17 154,305 -------------- $ 854,701 ---------------------------------------------------------------------------------------------------------- Consumer Finance -- 1.1% 500,000 A+/A1 American Honda Finance Corp., 2.375%, 3/18/13 (144A) $ 500,364 380,000 A+/A1 American Honda Finance Corp., 6.7%, 10/1/13 (144A) 393,219 500,000 BB+/Baa3 Banque PSA Finance SA, 3.375%, 4/4/14 (144A) 498,021 475,000 BBB/Baa1 Capital One Financial Corp., 1.0%, 11/6/15 473,280 500,000 BBB/Baa1 Capital One Financial Corp., 2.125%, 7/15/14 508,620 250,000 BB+/Baa3 Ford Motor Credit Co., LLC, 2.375%, 1/16/18 248,210 200,000 BB+/Baa3 Ford Motor Credit Co., LLC, 3.875%, 1/15/15 208,165 -------------- $ 2,829,879 ---------------------------------------------------------------------------------------------------------- Asset Management & Custody Banks -- 0.1% 300,000 AA-/A1 Franklin Resources, Inc., 3.125%, 5/20/15 $ 315,858 ---------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 40 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Investment Banking & Brokerage -- 2.3% 800,000 A-/Baa2 Merrill Lynch & Co., Inc., 6.15%, 4/25/13 $ 806,088 500,000 A-/Baa2 Merrill Lynch & Co., Inc., 5.0%, 2/3/14 518,518 1,000,000 A-/Baa1 Morgan Stanley, Inc., 4.0%, 9/22/20 (Step) 1,007,558 275,000 3.10 A-/Baa1 Morgan Stanley, Inc., Floating Rate Note, 11/9/18 278,056 500,000 1.54 A-/Baa1 Morgan Stanley, Inc., Floating Rate Note, 2/25/16 501,746 750,000 2.79 A-/Baa1 Morgan Stanley, Inc., Floating Rate Note, 5/14/13 753,156 250,000 A/A2 The Charles Schwab Corp., 0.85%, 12/4/15 250,828 340,000 A-/A3 The Goldman Sachs Group, Inc., 3.7%, 8/1/15 359,194 250,000 1.29 A-/A3 The Goldman Sachs Group, Inc., Floating Rate Note, 11/21/14 251,071 1,000,000 1.30 A-/A3 The Goldman Sachs Group, Inc., Floating Rate Note, 2/7/14 1,005,554 475,000 0.76 A-/A3 The Goldman Sachs Group, Inc., Floating Rate Note, 3/22/16 469,359 -------------- $ 6,201,128 -------------- Total Diversified Financials $ 24,103,436 ---------------------------------------------------------------------------------------------------------- INSURANCE -- 3.2% Life & Health Insurance -- 0.7% 50,000 A+/A1 Allstate Life Global Funding Trusts, 5.375%, 4/30/13 $ 50,383 500,000 A-/NR Jefferson-Pilot Corp., 4.75%, 1/30/14 518,024 250,000 A-/Baa2 Lincoln National Corp., 4.3%, 6/15/15 268,424 475,000 A/Baa2 Prudential Covered Trust 2012-1, 2.997%, 9/30/15 (144A) 495,941 500,000 0.00 BBB+/NR Vitality Re IV, Ltd., Floating Rate Note, 1/9/16 (Cat Bond) (144A) 502,750 -------------- $ 1,835,522 ---------------------------------------------------------------------------------------------------------- Multi-line Insurance -- 0.5% 500,000 BBB-/Baa3 Genworth Financial, Inc., 5.75%, 6/15/14 $ 525,026 410,000 BBB-/Baa2 Liberty Mutual Group, Inc., 7.3%, 6/15/14 (144A) 437,866 250,000 A/A2 Metropolitan Life Insurance Co., 7.7%, 11/1/15 (144A) 288,792 -------------- $ 1,251,684 ---------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 41 Schedule of Investments | 2/28/13 (unaudited) (continued) ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Property & Casualty Insurance -- 0.4% 500,000 BBB/Baa3 Sirius International Group, Ltd., 6.375%, 3/20/17 (144A) $ 562,718 500,000 BBB+/Baa2 XL Group Plc, 5.25%, 9/15/14 529,088 -------------- $ 1,091,806 ---------------------------------------------------------------------------------------------------------- Reinsurance -- 1.6% 250,000 8.18 BB-/NR Atlas Reinsurance VII, Ltd., Floating Rate Note, 1/7/16 (Cat Bond) (144A) $ 249,750 250,000 4.50 NR/Baa1 Combine Re, Ltd., Floating Rate Note, 1/7/15 (Cat Bond) (144A) 256,650 250,000 17.75 B+/NR Everglades Re, Ltd., Floating Rate Note, 4/30/14 (Cat Bond) (144A) 274,525 500,000 5.00 BB+/NR Foundation Re III, Ltd., Floating Rate Note, 2/25/15 (Cat Bond) 524,000 500,000 5.75 BB/NR Foundation Re III, Ltd., Floating Rate Note, 2/3/14 (Cat Bond) (144A) 507,050 250,000 7.00 BB-/NR Johnston Re, Ltd., Floating Rate Note, 5/8/13 (Cat Bond) (144A) 251,950 250,000 6.00 BB+/NR Longpoint Re, Ltd., Floating Rate Note, 6/12/15 (Cat Bond) (144A) 260,850 250,000 8.50 B+/NR Mythen Re, Ltd., Series 2012-2 Class A, Floating Rate Note, 1/5/17 (Cat Bond) (144A) 250,875 250,000 8.22 NR/Ba3 Mythen, Ltd., Floating Rate Note, 5/7/15 (Cat Bond) (144A) 265,575 250,000 8.60 B/NR Queen Street VII Re, Ltd., Floating Rate Note, 4/8/16 (Cat Bond) (144A) 249,850 400,000 4.50 BB+/NR Residential Reinsurance 2012, Ltd., Floating Rate Note, 12/6/16 (Cat Bond) (144A) 400,600 250,000 8.00 BB/NR Residential Reinsurance 2012, Ltd., Floating Rate Note, 6/6/16 (Cat Bond) (144A) 262,775 350,000 12.93 B-/NR Successor X, Ltd., Class III-R3, Floating Rate Note, 1/7/14 (Cat Bond) (144A) 352,100 300,000 9.41 B/NR Successor X, Ltd., Class IV-E3, Floating Rate Note, 2/25/14 (Cat Bond) (144A) 301,410 -------------- $ 4,407,960 -------------- Total Insurance $ 8,586,972 ---------------------------------------------------------------------------------------------------------- REAL ESTATE -- 1.3% Diversified REIT -- 0.1% 350,000 BBB/Baa2 Digital Realty Trust LP, 4.5%, 7/15/15 $ 372,681 ---------------------------------------------------------------------------------------------------------- Office REIT -- 0.2% 385,000 BBB/Baa2 Mack-Cali Realty LP, 5.125%, 2/15/14 $ 398,783 ---------------------------------------------------------------------------------------------------------- Specialized REIT -- 1.0% 1,000,000 BBB+/Baa1 HCP, Inc., 2.7%, 2/1/14 $ 1,016,620 The accompanying notes are an integral part of these financial statements. 42 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Specialized REIT -- (continued) 500,000 BBB-/Baa2 Health Care Real Estate Investment Trust, Inc., 2.25%, 3/15/18 $ 504,436 780,000 BBB-/Baa2 Hospitality Properties Trust, 7.875%, 8/15/14 826,539 290,000 BBB-/Baa3 Senior Housing Properties Trust, 4.3%, 1/15/16 301,713 -------------- $ 2,649,308 -------------- Total Real Estate $ 3,420,772 ---------------------------------------------------------------------------------------------------------- TECHNOLOGY HARDWARE & EQUIPMENT -- 0.2% Computer Hardware -- 0.2% 470,000 BBB+/Baa1 Hewlett-Packard Co., 2.625%, 12/9/14 $ 480,903 -------------- Total Technology Hardware & Equipment $ 480,903 ---------------------------------------------------------------------------------------------------------- SEMICONDUCTORS & SEMICONDUCTOR EQUIPMENT -- 0.5% Semiconductors -- 0.5% 700,000 A+/A1 Intel Corp., 1.35%, 12/15/17 $ 701,548 750,000 BBB+/Baa1 Maxim Integrated Products, Inc., 3.45%, 6/14/13 755,962 -------------- $ 1,457,510 -------------- Total Semiconductors & Semiconductor Equipment $ 1,457,510 ---------------------------------------------------------------------------------------------------------- TELECOMMUNICATION SERVICES -- 1.3% Integrated Telecommunication Services -- 1.0% 500,000 NR/A2 GTP Acquisition Partners I LLC, 4.347%, 6/15/16 (144A) $ 540,793 550,000 NR/A2 GTP Towers Issuer LLC, 4.436%, 2/15/15 (144A) 572,483 200,000 NR/Ba2 GTP Towers Issuer LLC, 8.112%, 2/15/15 (144A) 213,984 750,000 BBB/Baa3 Telecom Italia Capital SA, 4.95%, 9/30/14 776,250 500,000 BBB/Baa2 Telefonica Emisiones SAU, 3.992%, 2/16/16 516,054 -------------- $ 2,619,564 ---------------------------------------------------------------------------------------------------------- Wireless Telecommunication Services -- 0.3% 500,000 NR/A2 Crown Castle Towers LLC, 3.214%, 8/15/15 (144A) $ 522,546 275,000 0.68 A-/A3 Vodafone Group Plc, Floating Rate Note, 2/19/16 275,206 -------------- $ 797,752 -------------- Total Telecommunication Services $ 3,417,316 ---------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 43 Schedule of Investments | 2/28/13 (unaudited) (continued) ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- UTILITIES -- 1.3% Electric Utilities -- 0.9% 500,000 A/A2 Florida Power Corp., 0.65%, 11/15/15 $ 500,160 1,000,000 BBB/Baa1 Iberdrola Finance Ireland, Ltd., 3.8%, 9/11/14 (144A) 1,028,604 500,000 BBB+/Baa1 NextEra Energy Capital Holdings, Inc., 2.55%, 11/15/13 506,657 380,000 BBB+/Baa2 Northeast Utilities Co., 5.65%, 6/1/13 384,734 -------------- $ 2,420,155 ---------------------------------------------------------------------------------------------------------- Independent Power Producers & Energy Traders -- 0.4% 500,000 6.65 BB/NR East Lane Re, Ltd., Floating Rate Note, 3/13/15 (Cat Bond) (144A) $ 511,500 500,000 BBB/Baa1 PSEG Power LLC, 2.75%, 9/15/16 520,554 -------------- $ 1,032,054 -------------- Total Utilities $ 3,452,209 ---------------------------------------------------------------------------------------------------------- TOTAL CORPORATE BONDS (Cost $76,240,543) $ 77,463,312 ---------------------------------------------------------------------------------------------------------- U.S. GOVERNMENT AND AGENCY OBLIGATIONS -- 18.3% 73,751 AAA/Aaa Fannie Mae, 5.0%, 7/1/15 $ 79,755 152,501 AAA/Aaa Fannie Mae, 5.5%, 12/1/35 167,128 253,530 AAA/Aaa Fannie Mae, 6.0%, 2/1/34-4/1/38 282,545 452,631 AAA/Aaa Fannie Mae, 6.5%, 8/1/13-7/1/32 517,400 414,289 AAA/Aaa Fannie Mae, 7.0%, 7/1/17-1/1/36 469,341 24,170 AAA/Aaa Fannie Mae, 8.0%, 4/1/14 24,454 64,360 2.86 AAA/Aaa Fannie Mae, Floating Rate Note, 1/1/25 64,994 92,449 2.40 AAA/Aaa Fannie Mae, Floating Rate Note, 10/1/29 96,902 223,904 2.57 AAA/Aaa Fannie Mae, Floating Rate Note, 10/1/29 239,333 329,790 2.56 AAA/Aaa Fannie Mae, Floating Rate Note, 10/1/36 343,623 100,503 2.83 AAA/Aaa Fannie Mae, Floating Rate Note, 11/1/24 100,752 4,504 2.24 AAA/Aaa Fannie Mae, Floating Rate Note, 11/1/25 4,790 121,951 1.58 AAA/Aaa Fannie Mae, Floating Rate Note, 11/1/40 126,163 83,696 2.44 AAA/Aaa Fannie Mae, Floating Rate Note, 12/1/28 89,642 358,621 4.48 AAA/Aaa Fannie Mae, Floating Rate Note, 12/1/36 379,146 20,547 2.70 AAA/Aaa Fannie Mae, Floating Rate Note, 2/1/27 20,645 2,055 3.07 AAA/Aaa Fannie Mae, Floating Rate Note, 2/1/33 2,184 3,618 2.59 AAA/Aaa Fannie Mae, Floating Rate Note, 4/1/28 3,855 3,120 2.36 AAA/Aaa Fannie Mae, Floating Rate Note, 4/1/29 3,309 82,035 2.94 AAA/Aaa Fannie Mae, Floating Rate Note, 7/1/36 87,891 446,832 AAA/Aaa Federal Home Loan Mortgage Corp., 4.0%, 5/1/24 475,073 The accompanying notes are an integral part of these financial statements. 44 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- U.S. GOVERNMENT AND AGENCY OBLIGATIONS -- (continued) 1,007,829 AAA/Aaa Federal Home Loan Mortgage Corp., 4.5%, 7/1/19 $ 1,086,828 144,479 AAA/Aaa Federal Home Loan Mortgage Corp., 5.0%, 2/1/21 154,977 116,235 AAA/Aaa Federal Home Loan Mortgage Corp., 5.5%, 8/1/23 125,316 28,073 AAA/Aaa Federal Home Loan Mortgage Corp., 6.5%, 7/1/16-6/1/17 30,223 3,694 2.50 AAA/Aaa Federal Home Loan Mortgage Corp., Floating Rate Note, 1/1/28 3,955 464,658 2.94 AAA/Aaa Federal Home Loan Mortgage Corp., Floating Rate Note, 10/1/31 467,836 7,961 2.42 AAA/Aaa Federal Home Loan Mortgage Corp., Floating Rate Note, 11/1/31 8,483 287,733 2.78 AAA/Aaa Federal Home Loan Mortgage Corp., Floating Rate Note, 12/1/31 290,353 29,800 2.86 AAA/Aaa Federal Home Loan Mortgage Corp., Floating Rate Note, 4/1/25 29,925 2,088 2.65 AAA/Aaa Federal Home Loan Mortgage Corp., Floating Rate Note, 4/1/29 2,102 7,958 2.16 AAA/Aaa Federal Home Loan Mortgage Corp., Floating Rate Note, 5/1/25 7,987 6,889 2.35 AAA/Aaa Federal Home Loan Mortgage Corp., Floating Rate Note, 7/1/18 7,124 1,587 2.38 AAA/Aaa Federal Home Loan Mortgage Corp., Floating Rate Note, 8/1/31 1,591 159,177 2.96 AAA/Aaa Federal Home Loan Mortgage Corp., Floating Rate Note, 8/1/31 163,055 468,612 AAA/Aaa Government National Mortgage Association I, 5.0%, 8/15/19 518,329 874,075 AAA/Aaa Government National Mortgage Association I, 6.0%, 3/15/17-11/15/36 971,198 151,608 AAA/Aaa Government National Mortgage Association I, 6.5%, 5/15/31-10/15/37 174,783 1,707 AAA/Aaa Government National Mortgage Association I, 7.0%, 11/15/13 1,740 105,142 AAA/Aaa Government National Mortgage Association I, 7.5%, 6/15/14-10/15/36 126,847 1,875,799 AAA/Aaa Government National Mortgage Association II, 6.0%, 5/20/13-11/20/22 2,040,439 8,500,000 AA+/Aaa U.S. Treasury Notes, 0.125%, 12/31/13 8,496,676 16,150,000 AA+/Aaa U.S. Treasury Notes, 0.125%, 9/30/13 16,148,102 11,000,000 AA+/Aaa U.S. Treasury Notes, 0.25%, 10/31/13 11,006,875 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 45 Schedule of Investments | 2/28/13 (unaudited) (continued) ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- U.S. GOVERNMENT AND AGENCY OBLIGATIONS -- (continued) 3,500,000 AA+/Aaa U.S. Treasury Notes, 0.5%, 11/15/13 $ 3,508,477 -------------- $ 48,952,146 ---------------------------------------------------------------------------------------------------------- TOTAL U.S. GOVERNMENT AND AGENCY OBLIGATIONS (Cost $48,581,115) $ 48,952,146 ---------------------------------------------------------------------------------------------------------- MUNICIPAL BONDS -- 3.4% Municipal Airport -- 0.3% 300,000 BBB/A2 Massachusetts Port Authority, 5.0%, 7/1/14 $ 309,222 475,000 BBB/A2 Massachusetts Port Authority, 5.0%, 7/1/16 506,141 -------------- $ 815,363 ---------------------------------------------------------------------------------------------------------- Municipal Development -- 0.1% 250,000 3.00 AA-/Aa2 Massachusetts Development Finance Agency, Floating Rate Note, 2/15/36 $ 267,578 ---------------------------------------------------------------------------------------------------------- Municipal General -- 1.9% 500,000 AA/A2 Jobs Ohio Beverage System, 0.872%, 1/1/15 $ 500,745 1,500,000 1.31 A+/A1 New Jersey Economic Development Authority, Floating Rate Note, 6/15/13 1,501,905 2,000,000 NR/NR State of California, 2.5%, 6/20/13 2,014,020 500,000 AA/Aa2 State of Ohio, 3.0%, 6/15/15 523,350 500,000 BBB/A3 Texas Municipal Gas Acquisition & Supply Corp., III, 5.0%, 12/15/15 542,800 -------------- $ 5,082,820 ---------------------------------------------------------------------------------------------------------- Higher Municipal Education -- 0.5% 690,000 2.70 NR/A2 Massachusetts Health & Educational Facilities Authority, Floating Rate Note, 10/1/37 $ 704,442 200,000 AA-/Aa2 New York State Dormitory Authority, 3.0%, 7/1/13 201,910 500,000 AA/Aa1 University of California, 0.966%, 5/15/17 502,725 -------------- $ 1,409,077 ---------------------------------------------------------------------------------------------------------- Municipal Pollution -- 0.4% 1,000,000 A-/Baa1 County of Power Idaho, 5.625%, 10/1/14 $ 1,001,070 ---------------------------------------------------------------------------------------------------------- Municipal Transportation -- 0.2% 500,000 NR/NR North Texas Tollway Authority, 2.441%, 9/1/13 $ 505,210 ---------------------------------------------------------------------------------------------------------- TOTAL MUNICIPAL BONDS (Cost $9,054,527) $ 9,081,118 ---------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 46 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- SENIOR FLOATING RATE LOAN INTERESTS -- 2.1%** MATERIALS -- 0.1% Metal & Glass Containers -- 0.1% 195,000 4.50 B/B1 BWAY Holding Co., Initial Term Loan, 8/31/17 $ 197,194 ---------------------------------------------------------------------------------------------------------- Diversified Metals & Mining -- 0.0%+ 99,750 5.25 BB+/Ba1 Fortescue Metals Group, Ltd., Term Loan, 9/18/17 $ 101,184 -------------- Total Materials $ 298,378 ---------------------------------------------------------------------------------------------------------- CAPITAL GOODS -- 0.2% Aerospace & Defense -- 0.1% 248,125 3.75 BBB-/Ba1 Spirit Aerosystems, Inc., Term B Loan, 3/27/19 $ 249,934 ---------------------------------------------------------------------------------------------------------- Construction & Farm Machinery & Heavy Trucks -- 0.0%+ 148,129 4.50 NR/Ba2 Terex Corp., New US Term Loan, 4/28/17 $ 150,054 ---------------------------------------------------------------------------------------------------------- Trading Companies & Distributors -- 0.1% 245,000 4.50 B+/Ba3 WESCO International, Inc., Tranche B-1 Loan, 12/4/19 $ 247,833 -------------- Total Capital Goods $ 647,821 ---------------------------------------------------------------------------------------------------------- COMMERCIAL SERVICES & SUPPLIES -- 0.1% Environmental & Facilities Services -- 0.1% 170,895 2.31 CCC-/Caa2 Synagro Technologies, Inc., Term Loan (First Lien), 4/2/14 $ 160,385 -------------- Total Commercial Services & Supplies $ 160,385 ---------------------------------------------------------------------------------------------------------- AUTOMOBILES & COMPONENTS -- 0.4% Auto Parts & Equipment -- 0.0%+ 120,806 4.75 BBB/Baa2 Delphi Automotive LLP, Tranche B Term Loan, 3/31/17 $ 121,530 ---------------------------------------------------------------------------------------------------------- Automobile Manufacturers -- 0.4% 916,050 6.00 BB/Ba1 Chrysler Group LLC, Tranche B Term Loan, 4/28/17 $ 936,468 -------------- Total Automobiles & Components $ 1,057,998 ---------------------------------------------------------------------------------------------------------- CONSUMER DURABLES & APPAREL -- 0.1% Apparel, Accessories & Luxury Goods -- 0.1% 115,000 3.25 BBB-/Ba1 PVH Corp., Tranche B Term Loan, 12/19/19 $ 116,121 -------------- Total Consumer Durables & Apparel $ 116,121 ---------------------------------------------------------------------------------------------------------- CONSUMER SERVICES -- 0.3% Casinos & Gaming -- 0.3% 350,000 4.25 BB/Ba2 MGM Resorts International, Term B Loan, 12/13/19 $ 355,375 The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 47 Schedule of Investments | 2/28/13 (unaudited) (continued) ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- Casinos & Gaming -- (continued) 498,741 3.75 BBB-/Ba1 Penn National Gaming, Inc., Term B Facility Loan, 6/29/18 $ 501,996 -------------- $ 857,371 -------------- Total Consumer Services $ 857,371 ---------------------------------------------------------------------------------------------------------- MEDIA -- 0.2% Movies & Entertainment -- 0.2% 253,871 5.75 NR/Ba1 Cinedigm Digital Funding I LLC, Term Loan, 3/31/16 $ 255,458 194,503 4.50 BB-/Ba2 Live Nation Entertainment, Inc., Term B Loan, 10/20/16 196,203 -------------- $ 451,661 -------------- Total Media $ 451,661 ---------------------------------------------------------------------------------------------------------- HEALTH CARE EQUIPMENT & SERVICES -- 0.1% Health Care Facilities -- 0.1% 367,918 3.79 BB/Ba3 Community Health Systems, Inc., Extended Term Loan, 7/25/14 $ 371,166 -------------- Total Health Care Equipment & Services $ 371,166 ---------------------------------------------------------------------------------------------------------- DIVERSIFIED FINANCIALS -- 0.1% Investment Banking & Brokerage -- 0.1% 148,875 4.00 NR/Ba2 LPL Holdings, Inc., Initial Tranche B Term Loan, 3/6/19 $ 150,364 -------------- Total Diversified Financials $ 150,364 ---------------------------------------------------------------------------------------------------------- SOFTWARE & SERVICES -- 0.2% Internet Software & Services -- 0.1% 245,625 4.00 BB+/Ba3 Autotrader.com, Inc., Tranche B-1 Term Loan, 12/15/16 $ 248,143 ---------------------------------------------------------------------------------------------------------- IT Consulting & Other Services -- 0.1% 271,555 3.95 BB/Ba3 SunGard Data Systems, Inc., Tranche C Term Loan, 2/28/17 $ 273,647 -------------- Total Software & Services $ 521,790 ---------------------------------------------------------------------------------------------------------- TECHNOLOGY HARDWARE & EQUIPMENT -- 0.2% Communications Equipment -- 0.2% 510,000 4.00 BBB-/Ba3 Riverbed Technology, Inc., Loan, 10/29/19 $ 516,056 -------------- Total Technology Hardware & Equipment $ 516,056 ---------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 48 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 ---------------------------------------------------------------------------------------------------------- Principal Floating S&P/Moody's Amount ($) Rate (b) Ratings Value ---------------------------------------------------------------------------------------------------------- UTILITIES -- 0.1% Independent Power Producers & Energy Traders -- 0.1% 334,173 0.00 NR/NR AES Corp. Virginia, 2013 Other Term, 5/27/18 $ 336,680 -------------- Total Utilities $ 336,680 ---------------------------------------------------------------------------------------------------------- TOTAL SENIOR FLOATING RATE LOAN INTERESTS (Cost $5,369,526) $ 5,485,791 ---------------------------------------------------------------------------------------------------------- TOTAL INVESTMENT IN SECURITIES -- 100.0% (Cost $266,855,084) (a) $ 267,026,048 ---------------------------------------------------------------------------------------------------------- OTHER ASSETS & LIABILITIES -- 0.0% $ 72,631 ---------------------------------------------------------------------------------------------------------- TOTAL NET ASSETS -- 100.0% $ 267,098,679 ========================================================================================================== NR Not rated by either S&P or Moody's. WR Rating withdrawn by either S&P or Moody's. (Perpetual) Security with no stated maturity date. (Step) Bond issued with an initial coupon rate which converts to a higher rate at a later date. REIT Real Estate Investment Trust. + Amount rounds to less than 0.1%. (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, 2013, the value of these securities amounted to $65,068,530 or 24.4% of total net assets. ** Senior floating rate loan interests in which the Fund invests generally pay interest at rates that are periodically redetermined by reference to a base lending rate plus a premium. These base lending rates are generally (i) the lending rate offered by one or more major European banks, such as LIBOR (London InterBank Offered Rate), (ii) the prime rate offered by one or more major United States 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, 2013, the net unrealized loss on investments based on cost for federal income tax purposes of $267,273,990 was as follows: Aggregate gross unrealized gain for all investments in which there is an excess of value over tax cost $ 3,561,288 Aggregate gross unrealized loss for all investments in which there is an excess of tax cost over value (3,809,230) -------------- Net unrealized loss $ (247,942) ============== The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 49 Schedule of Investments | 2/28/13 (unaudited) (continued) (b) Debt obligation with a variable interest rate. Rate shown is rate at end of period. NOTE: Principal amounts are denominated in U.S. Dollars unless otherwise noted: CAD Canadian Dollar. Purchases and sales of securities (excluding temporary cash investments) for the six months ended February 28, 2013 were as follows: -------------------------------------------------------------------------------- Purchases Sales -------------------------------------------------------------------------------- Long-Term U.S. Government $38,172,196 $18,942,584 Other Long-Term Securities $74,662,334 $33,311,597 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. Generally, equity securities are categorized as Level 1, fixed income securities and senior loans as Level 2 and securities valued using fair value methods (other than prices supplied by independent pricing services) are categorized as Level 3. See Notes to Financial Statements -- Note 1A. The following is a summary of the inputs used as of February 28, 2013, in valuing the Fund's assets: ------------------------------------------------------------------------------------------ Level 1 Level 2 Level 3 Total ------------------------------------------------------------------------------------------ Asset Backed Securities $ -- $ 43,854,768 $ -- $ 43,854,768 Collateralized Mortgage Obligations -- 82,188,913 -- 82,188,913 Corporate Bonds -- 77,463,312 -- 77,463,312 U.S. Government And Agency Obligations -- 48,952,146 -- 48,952,146 Municipal Bonds -- 9,081,118 -- 9,081,118 Senior Floating Rate Loan Interests -- 5,485,791 -- 5,485,791 ------------------------------------------------------------------------------------------ Total $ -- $ 267,026,048 $ -- $267,026,048 ========================================================================================== Other Financial Instruments Unrealized loss on futures contracts $ (4,750) -- -- $ (4,750) ------------------------------------------------------------------------------------------ Total Other Financial Instruments $ (4,750) $ -- $ -- $ (4,750) ========================================================================================== Following is a reconciliation of assets using significant unobservable inputs (Level 3): The accompanying notes are an integral part of these financial statements. 50 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 Statement of Assets and Liabilities | 2/28/13 (unaudited) ASSETS: Investment in securities (cost $266,855,084) $267,026,048 Cash 754,834 Futures collateral 20,900 Foreign currencies, at value (cost $253,481) 245,032 Receivables -- Investment securities sold 348,176 Fund shares sold 719,397 Interest 1,106,058 Due from Pioneer Investment Management, Inc. 7,691 Prepaid expenses 34,031 ------------------------------------------------------------------------------------ Total assets $270,262,167 ------------------------------------------------------------------------------------ LIABILITIES: Payables -- Investment securities purchased $ 2,299,625 Fund shares repurchased 465,705 Dividends 251,361 Variation margin 2,375 Due to affiliates 69,017 Accrued expenses 75,405 ------------------------------------------------------------------------------------ Total liabilities $ 3,163,488 ------------------------------------------------------------------------------------ NET ASSETS: Paid-in capital $276,788,948 Distributions in excess of net investment income (328,591) Accumulated net realized loss on investments and foreign currency transactions (9,519,438) Net unrealized gain on investments 170,964 Net unrealized loss on forward foreign currency contracts and other assets and liabilities denominated in foreign currencies (8,454) Net unrealized loss on futures contracts (4,750) ------------------------------------------------------------------------------------ Total net assets $267,098,679 ==================================================================================== NET ASSET VALUE PER SHARE: (No par value, unlimited number of shares authorized) Class A (based on $78,374,542/8,056,631 shares) $ 9.73 Class B (based on $1,371,575/141,042 shares) $ 9.72 Class C (based on $30,228,395/3,114,428 shares) $ 9.71 Class Y (based on $157,124,167/16,181,805 shares) $ 9.71 MAXIMUM OFFERING PRICE: Class A ($9.73 (divided by) 97.5%) $ 9.98 ==================================================================================== The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 51 Statement of Operations (unaudited) For the Six Months Ended 2/28/13 INVESTMENT INCOME: Interest $ 4,059,020 ------------------------------------------------------------------------------------------ Total investment income $ 4,059,020 ------------------------------------------------------------------------------------------ EXPENSES: Management fees $ 486,553 Transfer agent fees and expenses Class A 14,719 Class B 2,593 Class C 6,210 Class Y 836 Distribution fees Class A 82,986 Class B 7,821 Class C 135,558 Shareholder communications expense 94,541 Administrative reimbursements 49,676 Custodian fees 32,230 Registration fees 26,541 Professional fees 32,009 Printing expense 11,096 Fees and expenses of nonaffiliated trustees 1,855 Miscellaneous 52,724 ------------------------------------------------------------------------------------------ Total expenses $ 1,037,948 ------------------------------------------------------------------------------------------ Less fees waived and expenses reimbursed by Pioneer Investment Management, Inc. (48,304) ------------------------------------------------------------------------------------------ Net expenses $ 989,644 ------------------------------------------------------------------------------------------ Net investment income $ 3,069,376 ------------------------------------------------------------------------------------------ REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS, FOREIGN CURRENCY TRANSACTIONS, AND FUTURES CONTRACTS: Net realized gain (loss) on: Investments $ (1,199,110) Futures contracts (15,187) Class actions 7,082 Forward foreign currency contracts and other assets and liabilities denominated in foreign currencies 185 $ (1,207,030) ------------------------------------------------------------------------------------------ Change in net unrealized loss on: Investments $ 1,002,556 Futures contracts 19,625 Forward foreign currency contracts and other assets and liabilities denominated in foreign currencies (7,204) $ 1,014,977 ------------------------------------------------------------------------------------------ Net loss on investments and foreign currency transactions $ (192,053) ------------------------------------------------------------------------------------------ Net increase in net assets resulting from operations $ 2,877,323 ========================================================================================== The accompanying notes are an integral part of these financial statements. 52 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 Statements of Changes in Net Assets ----------------------------------------------------------------------------------------------------- Six Months Ended 2/28/13 Year Ended (unaudited) 8/31/12 ----------------------------------------------------------------------------------------------------- FROM OPERATIONS: Net investment income $ 3,069,376 $ 6,056,993 Net realized gain (loss) on investments, futures contracts and foreign currency transactions (1,207,030) 35,525 Change in net unrealized gain (loss) on investments, futures contracts and foreign currency transactions 1,014,977 1,748,029 ----------------------------------------------------------------------------------------------------- Net increase in net assets resulting from operations $ 2,877,323 $ 7,840,547 ----------------------------------------------------------------------------------------------------- DISTRIBUTIONS TO SHAREOWNERS: Net investment income: Class A ($0.13 and $0.30 per share, respectively) $ (872,892) $ (1,713,026) Class B ($0.08 and $0.21 per share, respectively) (13,651) (54,200) Class C ($0.09 and $0.22 per share, respectively) (254,189) (549,094) Class Y ($0.14 and $0.33 per share, respectively) (2,200,292) (4,204,921) ----------------------------------------------------------------------------------------------------- Total distributions to shareowners $ (3,341,024) $ (6,521,241) ===================================================================================================== FROM FUND SHARE TRANSACTIONS: Net proceeds from sale or exchange of shares $ 89,436,884 $ 89,439,000 Reinvestment of distributions 1,503,386 2,553,715 Cost of shares repurchased (37,759,011) (138,523,080) ----------------------------------------------------------------------------------------------------- Net increase (decrease) in net assets resulting from Fund share transactions $ 53,181,259 $ (46,530,365) ----------------------------------------------------------------------------------------------------- Net increase (decrease) in net assets $ 52,717,558 $ (45,211,059) NET ASSETS: Beginning of period 214,381,121 259,592,180 ----------------------------------------------------------------------------------------------------- End of period $267,098,679 $ 214,381,121 ----------------------------------------------------------------------------------------------------- Distributions in excess of net investment income $ (328,591) $ (56,943) ===================================================================================================== The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 53 Statements of Changes in Net Assets (continued) ----------------------------------------------------------------------------------------- '13 Shares '13 Amount (unaudited) (unaudited) '12 Shares '12 Amount ----------------------------------------------------------------------------------------- Class A Shares sold 3,716,684 $ 36,191,625 3,998,534 $ 38,870,067 Reinvestment of distributions 75,659 736,409 156,155 1,504,946 Less shares repurchased (1,417,692) (13,523,012) (10,306,515) (99,329,477) ----------------------------------------------------------------------------------------- Net increase (decrease) 2,374,651 $ 23,405,022 (6,151,826) $ (58,954,464) ========================================================================================= Class B Shares sold or exchanged 36,551 $ 355,899 106,867 $ 1,028,704 Reinvestment of distributions 1,358 13,216 5,256 50,606 Less shares repurchased (71,353) (681,342) (214,898) (2,067,368) ----------------------------------------------------------------------------------------- Net decrease (33,444) $ (312,227) (102,775) $ (988,058) ========================================================================================= Class C Shares sold 922,054 $ 8,958,130 1,089,706 $ 10,473,902 Reinvestment of distributions 22,069 214,359 48,157 463,195 Less shares repurchased (390,562) (3,658,982) (1,016,608) (9,776,637) ----------------------------------------------------------------------------------------- Net increase 553,561 $ 5,513,507 121,255 $ 1,160,460 ========================================================================================= Class Y Shares sold 4,501,101 $ 43,931,230 4,058,961 $ 39,066,327 Reinvestment of distributions 55,506 539,402 55,564 534,968 Less shares repurchased (2,046,878) (19,895,675) (2,843,245) (27,349,598) ----------------------------------------------------------------------------------------- Net increase 2,509,729 $ 24,574,957 1,271,280 $ 12,251,697 ========================================================================================= The accompanying notes are an integral part of these financial statements. 54 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 Financial Highlights ------------------------------------------------------------------------------------------------------------------------------------ Six Months Ended Year Year Year Year Year 2/28/13 Ended Ended Ended Ended Ended (unaudited) 8/31/12 8/31/11 8/31/10 8/31/09 8/31/08 ------------------------------------------------------------------------------------------------------------------------------------ Class A Net asset value, beginning of period $ 9.72 $ 9.64 $ 9.75 $ 9.40 $ 9.52 $ 9.76 ------------------------------------------------------------------------------------------------------------------------------------ Increase from investment operations: Net investment income $ 0.12 $ 0.28 $ 0.23 $ 0.31 $ 0.37 $ 0.45 Net realized and unrealized gain (loss) on investments and foreign currency transactions 0.02 0.10 (0.07) 0.36 (0.03) (0.24) ------------------------------------------------------------------------------------------------------------------------------------ Net increase from investment operations $ 0.14 $ 0.38 $ 0.16 $ 0.67 $ 0.34 $ 0.21 ------------------------------------------------------------------------------------------------------------------------------------ Distributions to shareowners: Net investment income (0.13) (0.30) (0.27) (0.32) (0.46) (0.45) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ 0.01 $ 0.08 $ (0.11) $ 0.35 $ (0.12) $ (0.24) ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 9.73 $ 9.72 $ 9.64 $ 9.75 $ 9.40 $ 9.52 ==================================================================================================================================== Total return* 1.42% 4.00% 1.69% 7.19% 3.90% 2.18% Ratio of net expenses to average net assets+ 0.90%** 0.90% 0.90% 0.90% 0.90% 0.91% Ratio of net investment income to average net assets+ 2.42%** 2.94% 2.48% 2.78% 3.59% 4.60% Portfolio turnover rate 43%** 43% 54% 42% 43% 34% Net assets, end of period (in thousands) $78,375 $55,212 $114,080 $130,524 $19,544 $12,499 Ratios with no waiver of fees and assumption of expenses by the Adviser and no reduction for fees paid indirectly: Total expenses 1.04%** 1.30% 0.99% 1.06% 1.15% 1.00% Net investment income 2.28%** 2.54% 2.39% 2.61% 3.35% 4.51% Ratios with waiver of fees and assumption of expenses by the Adviser and reduction for fees paid indirectly: Net expenses 0.90%** 0.90% 0.90% 0.90% 0.90% 0.90% Net investment income 2.42%** 2.94% 2.48% 2.78% 3.59% 4.61% ==================================================================================================================================== * 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. + Ratio with no reduction for fees paid indirectly. The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 55 Financial Highlights (continued) ------------------------------------------------------------------------------------------------------------------------- Six Months Ended Year Year Year Year Year 2/28/13 Ended Ended Ended Ended Ended (unaudited) 8/31/12 8/31/11 8/31/10 8/31/09 8/31/08 ------------------------------------------------------------------------------------------------------------------------- Class B Net asset value, beginning of period $ 9.71 $ 9.63 $ 9.75 $ 9.39 $ 9.50 $ 9.75 ------------------------------------------------------------------------------------------------------------------------- Increase from investment operations: Net investment income $ 0.08 $ 0.20 $ 0.14 $ 0.22 $ 0.28 $ 0.36 Net realized and unrealized gain (loss) on investments and foreign currency transactions 0.01 0.09 (0.07) 0.37 (0.01) (0.25) ------------------------------------------------------------------------------------------------------------------------- Net increase from investment operations $ 0.09 $ 0.29 $ 0.07 $ 0.59 $ 0.27 $ 0.11 ------------------------------------------------------------------------------------------------------------------------- Distributions to shareowners: Net investment income (0.08) (0.21) (0.19) (0.23) (0.38) (0.36) ------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) in net asset value $ 0.01 $ 0.08 $ (0.12) $ 0.36 $ (0.11) $ (0.25) ------------------------------------------------------------------------------------------------------------------------- Net asset value, end of period $ 9.72 $ 9.71 $ 9.63 $ 9.75 $ 9.39 $ 9.50 ========================================================================================================================= Total return* 0.96% 3.08% 0.68% 6.35% 3.06% 1.16% Ratio of net expenses to average net assets+ 1.80%** 1.80% 1.80% 1.80% 1.80% 1.80% Ratio of net investment income to average net assets+ 1.60%** 2.10% 1.64% 2.37% 3.15% 3.72% Portfolio turnover rate 43%** 43% 54% 42% 43% 34% Net assets, end of period (in thousands) $1,372 $1,695 $ 2,671 $4,822 $ 6,582 $ 6,798 Ratios with no waiver of fees and assumption of expenses by the Adviser and no reduction for fees paid indirectly: Total expenses 1.94%** 1.99% 1.87% 1.88% 1.95% 1.85% Net investment income 1.46%** 1.90% 1.57% 2.29% 3.00% 3.67% Ratios with waiver of fees and assumption of expenses by the Adviser and reduction for fees paid indirectly: Net expenses 1.80%** 1.80% 1.80% 1.80% 1.80% 1.80% Net investment income 1.60%** 2.10% 1.64% 2.37% 3.15% 3.72% ========================================================================================================================= * 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. + Ratio with no reduction for fees paid indirectly. The accompanying notes are an integral part of these financial statements. 56 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 --------------------------------------------------------------------------------------------------------------------------- Six Months Ended Year Year Year Year Year 2/28/13 Ended Ended Ended Ended Ended (unaudited) 8/31/12 8/31/11 8/31/10 8/31/09 8/31/08 --------------------------------------------------------------------------------------------------------------------------- Class C Net asset value, beginning of period $ 9.70 $ 9.62 $ 9.73 $ 9.38 $ 9.49 $ 9.74 --------------------------------------------------------------------------------------------------------------------------- Increase from investment operations: Net investment income $ 0.09 $ 0.20 $ 0.16 $ 0.23 $ 0.29 $ 0.37 Net realized and unrealized gain (loss) on investments and foreign currency transactions 0.01 0.10 (0.07) 0.36 (0.01) (0.25) --------------------------------------------------------------------------------------------------------------------------- Net increase from investment operations $ 0.10 $ 0.30 $ 0.09 $ 0.59 $ 0.28 $ 0.12 --------------------------------------------------------------------------------------------------------------------------- Distributions to shareowners: Net investment income (0.09) (0.22) (0.20) (0.24) (0.39) (0.37) --------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) in net asset value $ 0.01 $ 0.08 $ (0.11) $ 0.35 $ (0.11) $ (0.25) --------------------------------------------------------------------------------------------------------------------------- Net asset value, end of period $ 9.71 $ 9.70 $ 9.62 $ 9.73 $ 9.38 $ 9.49 =========================================================================================================================== Total return* 1.04% 3.18% 0.93% 6.32% 3.14% 1.25% Ratio of net expenses to average net assets+ 1.67%** 1.71% 1.67% 1.70% 1.79% 1.73% Ratio of net investment income to average net assets+ 1.67%** 2.08% 1.61% 2.27% 2.74% 3.77% Portfolio turnover rate 43%** 43% 54% 42% 43% 34% Net assets, end of period (in thousands) $30,228 $24,830 $23,464 $20,507 $ 8,549 $ 3,441 Ratios with no waiver of fees and assumption of expenses by the Adviser and no reduction for fees paid indirectly: Total expenses 1.67%** 1.71% 1.67% 1.70% 1.79% 1.73% Net investment income 1.67%** 2.08% 1.61% 2.27% 2.74% 3.77% Ratios with waiver of fees and assumption of expenses by the Adviser and reduction for fees paid indirectly: Net expenses 1.67%** 1.71% 1.67% 1.70% 1.79% 1.73% Net investment income 1.67%** 2.08% 1.61% 2.27% 2.74% 3.77% =========================================================================================================================== * Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions, the complete redemption of the investment at net asset value at the end of each period, and no sales charges. Total return would be reduced if sales charges were taken into account. + Ratio with no reduction for fees paid indirectly. The accompanying notes are an integral part of these financial statements. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 57 Financial Highlights (continued) ------------------------------------------------------------------------------------------------------------------------------- Six Months Ended Year Year Year Year Year 2/28/13 Ended Ended Ended Ended Ended (unaudited) 8/31/12 8/31/11 8/31/10 8/31/09 8/31/08 ------------------------------------------------------------------------------------------------------------------------------- Class Y Net asset value, beginning of period $ 9.70 $ 9.63 $ 9.74 $ 9.38 $ 9.51 $ 9.76 ------------------------------------------------------------------------------------------------------------------------------- Increase from investment operations: Net investment income $ 0.14 $ 0.31 $ 0.27 $ 0.34 $ 0.40 $ 0.48 Net realized and unrealized gain (loss) on investments and foreign currency transactions 0.01 0.09 (0.07) 0.37 (0.04) (0.24) ------------------------------------------------------------------------------------------------------------------------------- Net increase from investment operations $ 0.15 $ 0.40 $ 0.20 $ 0.71 $ 0.36 $ 0.24 ------------------------------------------------------------------------------------------------------------------------------- Distributions to shareowners: Net investment income (0.14) (0.33) (0.31) (0.35) (0.49) (0.49) ------------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) in net asset value $ 0.01 $ 0.07 $ (0.11) $ 0.36 $ (0.13) $ (0.25) ------------------------------------------------------------------------------------------------------------------------------- Net asset value, end of period $ 9.71 $ 9.70 $ 9.63 $ 9.74 $ 9.38 $ 9.51 =============================================================================================================================== Total return* 1.59% 4.24% 2.06% 7.64% 4.11% 2.45% Ratio of net expenses to average net assets+ 0.61% 0.61% 0.54% 0.57% 0.63% 0.55% Ratio of net investment income to average net assets+ 2.74% 3.18% 2.78% 3.52% 4.36% 4.98% Portfolio turnover rate 43% 43% 54% 42% 43% 34% Net assets, end of period (in thousands) $157,124 $132,644 $119,377 $115,153 $97,370 $130,475 Ratios with no waiver of fees and assumption of expenses by the Adviser and no reduction for fees paid indirectly: Total expenses 0.61% 0.61% 0.54% 0.57% 0.63% 0.55% Net investment income 2.74% 3.18% 2.78% 3.52% 4.36% 4.98% Ratios with waiver of fees and assumption of expenses by the Adviser and reduction for fees paid indirectly: Net expenses 0.61% 0.61% 0.54% 0.57% 0.63% 0.55% Net investment income 2.74% 3.18% 2.78% 3.52% 4.36% 4.98% =============================================================================================================================== * 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. + Ratio with no reduction for fees paid indirectly. ** Annualized. The accompanying notes are an integral part of these financial statements. 58 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 Notes to Financial Statements | 2/28/13 (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 four classes of shares designated as Class A, Class B, Class C, and Class Y shares. Effective as of the close of business on December 31, 2009, Class B shares are no longer offered to new or existing shareholders, except that dividends and/or capital gain distributions may continue to be reinvested in Class B shares, and shareholders may exchange their Class B shares for Class B shares of other Pioneer funds, as permitted by existing exchange privileges. 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 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. Class B shares convert to Class A shares approximately eight years after the date of purchase. The Fund's financial statements have been prepared in conformity with U.S. generally accepted accounting principles that require the management of the Fund to, among other things, 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 following is a summary of significant accounting policies followed by the Fund in the preparation of its financial statements, which are consistent with those policies generally accepted in the investment company industry: Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 59 A. Security Valuation Security transactions are recorded as of trade date. 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. Senior floating rate loan interests (senior loans) 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. Senior loans for which no reliable price quotes are available will be valued using inputs/data furnished by Loan Pricing Corporation through the use of pricing matrices to determine valuations. Fixed income securities with remaining maturity of more than sixty days are valued at 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. Valuations may be supplemented by dealers and other sources, as required. Short-term fixed income securities with remaining maturities of sixty days or less generally are valued at amortized cost. Securities or senior loans for which independent pricing services 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 or at the direction or with the approval of the Valuation Committee using fair value methods pursuant to procedures adopted by the Board of Trustees. The Valuation Committee is comprised of certain members of the Board of Trustees. 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. Pioneer Investment Management, Inc. (PIM) 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. At February 28, 2013, no securities were valued using fair value methods (other than securities valued using prices supplied by independent pricing services). 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. 60 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 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 debt securities are accreted/amortized for financial reporting purposes over the life of the respective securities, and such accretion/amortization is included in interest income. Interest income, including interest on income bearing cash accounts, is recorded on the accrual basis, net of unrecoverable foreign taxes withheld at the applicable country rates. Gains and losses on sales of investments are calculated on the identified cost method for both financial reporting and federal income tax purposes. B. 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 market price of those securities but are included with the net realized and unrealized gain or loss on investments. C. Forward Foreign Currency Contracts The Fund may enter into forward foreign currency contracts (contracts) for the purchase or sale of a specific foreign currency at a fixed price on a future date. All contracts are marked to market daily at the applicable exchange rates, and any resulting unrealized gains or losses are recorded in the Fund's financial statements. The Fund records realized gains and losses at the time a portfolio hedge is offset by entry into a closing transaction or extinguished by delivery of the currency. Risks may arise upon entering into these contracts from the potential inability of counterparties to meet the terms of the contract and from unanticipated movements in the value of foreign currencies relative to the U.S. dollar (see Note 6). 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 taxable income and net realized capital gains, if any, to its shareowners. Therefore, no provision for federal income taxes is required. As Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 61 of February 28, 2013, the Fund did not have any interest and penalties related to uncertain tax positions, which, if applicable, would be recorded as an income tax expense in the Statement of Operations. Tax years for the prior three fiscal 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. generally accepted accounting principles. Distributions in excess of net investment income or net realized gains are temporary overdistributions for financial statement purposes resulting from differences in the recognition or classification of income or distributions for financial statement and tax purposes. Capital accounts within the financial statements are adjusted for permanent book/tax differences to reflect tax character, but are not adjusted for temporary differences. The tax character of distributions paid during the years ended August 31, 2012 and August 31, 2011 were as follows: ---------------------------------------------------------------------------- 2012 ---------------------------------------------------------------------------- Distributions paid from: Ordinary income $6,521,241 ---------------------------------------------------------------------------- Total $6,521,241 ============================================================================ The following shows the components of distributable earnings on a federal income tax basis at August 31, 2012: ---------------------------------------------------------------------------- 2012 ---------------------------------------------------------------------------- Distributable earnings: Undistributed ordinary income $ 328,180 Capital loss carryforward (7,964,436) Current year dividend payable (339,814) Unrealized depreciation (1,250,498) ---------------------------------------------------------------------------- Total $ (9,226,568) ============================================================================ The difference between book-basis and tax-basis net unrealized gain is attributable to the tax deferral of losses on wash sales, adjustments relating to catastrophe bonds, the tax treatment of premium and amortization and, the mark to market of futures and forward 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 S.p.A. (UniCredit), earned $5,234 in underwriting commissions on the sale of Class A shares during the six months ended February 28 2013. 62 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 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. During the six months ended February 28, 2013, the Fund recognized gains of $7,082 in settlement of class action lawsuits from several different companies, as reflected on the Statement of Operations. Distribution fees are calculated based on the average daily net asset value attributable to Class A, Class B, and Class C shares of the Fund, respectively (see Note 4). Class Y shares do not pay distribution fees. All expenses and fees paid to the transfer agent, Pioneer Investment Management Shareholder Services, Inc. (PIMSS), for its services are allocated among the classes of shares based on the number of accounts in each class and the ratable allocation of related out-of-pocket expenses (see Note 3). The Fund declares as daily dividends substantially all of its net investment income. All dividends are paid on a monthly basis. Short-term capital gain distributions, if any, may be declared with the daily dividends. Distributions to shareowners are recorded as of the ex-dividend date. Distributions paid by the Fund with respect to each class of shares are calculated in the same manner and at the same time except that net investment income dividends to Class A, Class B, Class C and Class Y shares can reflect different transfer agent and distribution expense rates. G. Risks 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. Futures Contracts The Fund may enter into futures transactions 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. The amount of cash deposited with the broker as collateral at February 28, 2013 was $20,900. 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. Subsequent payments for futures contracts ("variation margin") are paid or received by Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 63 the Fund, depending on the daily fluctuation in the value of the contracts, and are recorded by the Fund as unrealized gains or losses. 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 involves, to varying degrees, elements of market, interest rate, currency exchange rate and counterparty risks, which may exceed the amounts recognized by the Fund. Changes in value of the contracts may not directly correlate to the changes in value of the underlying securities. These risks may decrease the effectiveness of the Fund's hedging strategies and potentially result in a loss. The average number of contracts open for the six months ended February 28, 2013 was 39. At February 28, 2013, open futures contracts were as follows. -------------------------------------------------------------------------------- Number of Contracts Settlement Unrealized Type Long/(Short) Month Value Loss -------------------------------------------------------------------------------- US 5 Yr Note (38) 6/13 $ (4,711,406) $ (4,750) -------------------------------------------------------------------------------- Total (38) $ (4,711,406) $ (4,750) -------------------------------------------------------------------------------- I. Repurchase Agreements With respect to repurchase agreements entered into by the Fund, the value of the underlying securities (collateral), including accrued interest, is required to be equal to or in excess of the repurchase price. The collateral for all repurchase agreements is held in safekeeping in the customer-only account of the Fund's custodian or a subcustodian of the Fund. The Fund's investment adviser, Pioneer Investment Management, Inc. (PIM), is responsible for determining that the value of the collateral remains at least equal to the repurchase price. 2. Management Agreement PIM, a wholly owned indirect subsidiary of UniCredit, manages the Fund's portfolio. Management fees are calculated daily at the annual rate of 0.40% of the Fund's average daily net assets. PIM has contractually agreed to limit ordinary operating expenses to the extent required to reduce Fund expenses to 0.90%, 1.80% and 1.80% of the average daily net assets attributable to Class A, Class B and Class C shares, respectively. Fees waived and expenses reimbursed during the six months ended February 28, 2013 are reflected on the Statement of Operations. These expense limitations are in effect through January 1, 2014 for Class A, Class B, and Class C shares. The expense limit in effect through June 1, 2012 for Class Y shares was 0.79%. There can be no assurance that PIM will extend the expense limitation agreement for a class of shares beyond the dates referred to above. 64 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 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 $9,320 in management fees, administrative costs and certain other reimbursements payable to PIM at February 28, 2013. Effective March 5, 2012, PIM has retained Brown Brothers Harriman & Co. to provide certain sub-administration and accounting services to the Fund. 3. Transfer Agent PIMSS, a wholly owned indirect subsidiary of UniCredit, provides substantially all transfer agent and shareowner services to the Fund at negotiated rates. In addition, the Fund reimburses PIMSS for out-of-pocket expenses incurred by PIMSS related to shareholder communications activities such as proxy and statement mailings, outgoing phone calls and omnibus relationship contracts. For the six months ended February 28, 2013, such out-of-pocket expenses by class of shares were as follows: -------------------------------------------------------------------------------- Shareholder Communications: -------------------------------------------------------------------------------- Class A $58,812 Class B 334 Class C 6,624 Class Y 28,771 -------------------------------------------------------------------------------- Total $94,541 ================================================================================ Included in "Due to affiliates" reflected on the Statement of Assets and Liabilities is $56,901 in transfer agent fees and out-of-pocket reimbursements payable to PIMSS at February 28, 2013. 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, Class B and Class C shares. Pursuant to the Plan, the Fund pays PFD 0.25% of the average daily net assets attributable to Class A shares as compensation for personal services and/or account maintenance services or distribution services with regard to Class A shares. Pursuant to the Plan, the Fund also pays PFD 1.00% of the average daily net assets attributable to Class B and Class C shares. The fee for Class B and Class C shares consists of a 0.25% service fee and a 0.75% distribution fee paid as compensation for personal services and/or account maintenance services or distribution services with regard to Class B and Class C shares. Included in "Due to affiliates" reflected on the Statement of Assets and Liabilities is $2,796 in distribution fees payable to PFD at February 28, 2013. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 65 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. Class B shares that are redeemed within three years of purchase are subject to a CDSC at declining rates beginning at 2.00%, based on the lower of cost or market value of shares being redeemed. Redemptions of Class C shares within one year of purchase are subject to a CDSC of 1.00%, based on the lower of cost or market value of shares being redeemed. Shares purchased as part of an exchange remain subject to any CDSC that applied to the original purchase of those shares. There is no CDSC for Class Y shares. Proceeds from the CDSCs are paid to PFD. For the six months ended February 28, 2013, CDSCs in the amount of $17,954 were paid to PFD. 5. Expense Offset Arrangements The Fund has entered into certain expense offset arrangements with PIMSS, which may result in a reduction in the Fund's total expenses due to interest earned on cash held by PIMSS. For the six months ended February 28, 2013, the Fund's expenses were not reduced under such arrangements. 6. Forward Foreign Currency Contracts At February 28, 2013, the Fund had entered into various forward foreign currency contracts that obligate the Fund to deliver or take delivery of currencies at specified future maturity dates. Alternatively, prior to the settlement date of a forward foreign currency contract, the Fund may close out such contract by entering into an offsetting contract. The average value of contracts open during the six months ended February 28, 2013 was $63,091. There were no open portfolio or settlement hedges at February 28, 2013. 7. Additional Disclosures about Derivative Instruments and Hedging Activities: Values of derivative instruments as of February 28, 2013 were as follows: ------------------------------------------------------------------------------------------ Derivatives Not Accounted for as Asset Derivatives 2012 Liabilities Derivatives 2012 Hedging Instruments ---------------------------- -------------------------------- Under Accounting Statement of Assets Statement of Assets Standards Codification and Liabilities and Liabilities (ASC) 815 Location Value Location Value ------------------------------------------------------------------------------------------ Futures Contracts* Net unrealized $ -- Net unrealized $(4,750)* appreciation on depreciation on futures contracts futures contracts ------------------------------------------------------------------------------------------ Total $ -- $(4,750) ------------------------------------------------------------------------------------------ * Includes cumulative gain (loss) on futures as reported in the Notes to Financial Statements. Only unsettled receivable/payable for variation margin is included within the Statement of Assets and Liabilities. 66 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 The effect of derivative instruments on the Statement of Operations for the six months ended February 28, 2013 was as follows: ----------------------------------------------------------------------------------------- Derivatives Not Realized Change in Accounted for as Gain or Unrealized Hedging Instruments Loss on Gain or (Loss) Under Accounting Location of Gain or (Loss) Derivatives on Derivatives Standards Codification on Derivatives Recognized Recognized Recognized (ASC) 815 in Income in Income in Income ----------------------------------------------------------------------------------------- Forward foreign Net realized gain (loss) on currency portfolio forward foreign currency hedge contracts contracts and other assets and liabilities denominated in foreign currencies $ (9,542) Forward foreign Change in unrealized gain currency portfolio (loss) on forward foreign hedge contracts currency contracts and other assets and liabilities denominated in foreign currencies $ 6,621 Interest rate futures Net realized gain (loss) on futures contracts $(15,187) Interest rate futures Change in net unrealized gain (loss) on futures contracts $19,625 8. Line of Credit Facility The Fund, along with certain other funds in the Pioneer Family of Funds (the Funds), participates in a committed, unsecured revolving line of credit facility. Borrowings are used solely for temporary or emergency purposes. The Fund may borrow up to the lesser of the amount available under the facility or the limits set for borrowing by the Fund's prospectus and the 1940 Act. The credit facility in effect as of February 15, 2012 is in the amount of $215 million. Under such facility, depending on the type of loan, interest on borrowings is payable at the London Interbank Offered Rate (LIBOR) plus 0.90% on an annualized basis, or the alternate base rate, which is the greater of (a) the facility's administrative agent's daily announced prime rate on the borrowing date, (b) 2% plus the federal funds rate on the borrowing date and (c) 2% plus the overnight eurodollar rate on the borrowing date. The Funds pay an annual commitment fee to participate in the credit facility. The commitment fee is allocated among participating Funds based on an allocation schedule set forth in the credit agreement. For the six months ended February 28, 2013, the Fund had no borrowings under the credit facility. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 67 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 March 2012 as the Trustees of the Fund agreed on, among other things, an overall approach and timeline for the process. In July 2012, the Trustees approved the format of the contract review materials and submitted their formal request to PIM to furnish information necessary to evaluate the terms of the investment advisory agreement. The contract review materials were provided to the Trustees in July 2012 and September 2012. After reviewing and discussing the materials, the Trustees submitted a request for additional information to PIM, and materials were provided in response to this request. Meetings of the Independent Trustees of the Fund were held in July, September, October, and November, 2012 to review and discuss the contract review materials. In addition, the Trustees took into account the information related to the Fund provided to the Trustees at each regularly scheduled meeting. At a meeting held on November 13, 2012, 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 considering 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. 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 reviewed the terms of the investment advisory agreement. The Trustees also reviewed PIM's investment approach for the Fund, its research process and its process for trade execution. The Trustees considered the resources of PIM and the personnel of PIM who provide investment management services to 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 also considered the substantial attention and high priority given by PIM's senior management to the Pioneer fund complex. In addition, the Trustees considered PIM's plans to increase resources in its investment management function and other enhancements to PIM's advisory capabilities. 68 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 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 The Trustees considered the performance results of the Fund over various time periods. They reviewed information comparing the Fund's performance with the performance of its peer group of funds as classified by Morningstar, Inc. (Morningstar), an independent provider of investment company data, and with the performance of the Fund's benchmark index. The Trustees considered that the Fund's annualized total return was in the second quintile of its Morningstar category for the one and three year periods ended June 30, 2012 and in the third quintile of its Morningstar category for the five year period ended June 30, 2012. (In all quintile rankings referred to throughout this disclosure, first quintile is most favorable to the Fund's shareowners. Thus, highest relative performance would be first quintile and lowest relative expenses would also be first quintile.) The Trustees also considered that the Fund's twelve month average gross portfolio yield (using month end 30 day effective yields) exceeded the twelve month average yield of the Fund's benchmark index. The Trustees concluded that the investment performance of the Fund was satisfactory. 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 Mutual Trust Research and Consulting, LLC (Strategic Insight), an independent third party. The Trustees considered that the Fund's management fee for the twelve months ended June 30, 2012 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 that the Fund's expense ratio for the twelve months ended June 30, 2012 was in the fifth quintile relative to its Strategic Insight peer group for the comparable period. The Trustees considered that the Fund's Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 69 expense ratio was only 5.3 basis points higher than the median expense ratio of the Fund's Strategic Insight peer group. The Trustees considered the impact of the Fund's non-management fee expenses on the Fund's expense ratio, noting in particular the Fund's shareholder fees and communications expenses. The Trustees reviewed management fees charged by PIM and PIM's affiliate, Pioneer Institutional Asset Management, Inc. (together with PIM, "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 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. 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 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. 70 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 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 recognize that economies of scale are difficult to identify and quantify, rarely identifiable on a Fund-by-Fund basis, 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 Funds. 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 particularly, for example during the recent difficult periods for financial markets, as the level of services was maintained notwithstanding a significant decline in PIM's fee revenues from the Funds. Accordingly, the Trustees concluded that economies of scale, if any, were being appropriately shared with the Fund. 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. The Trustees considered the intangible benefits to PIM by virtue of its relationship with the Fund and the other Pioneer funds. The Trustees concluded that the receipt of these benefits was reasonable in the context of the overall relationship between PIM and the Fund. 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. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 71 Trustees, Officers and Service Providers Trustees Officers Thomas J. Perna, Chairman John F. Cogan, Jr., President* David R. Bock Daniel K. Kingsbury, Executive John F. Cogan, Jr. Vice President Benjamin M. Friedman Mark E. Bradley, Treasurer** Margaret B.W. Graham Christopher J. Kelley, Secretary Daniel K. Kingsbury Marguerite A. Piret Stephen K. West Investment Adviser and Administrator Pioneer Investment Management, Inc. Custodian and Sub-Administrator Brown Brothers Harriman & Co. Principal Underwriter Pioneer Funds Distributor, Inc. Legal Counsel Bingham McCutchen LLP Shareowner Services and Transfer Agent Pioneer Investment Management Shareholder 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. * Chief Executive Officer of the Fund. ** Chief Financial and Accounting Officer of the Fund. 72 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 This page for your notes. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 73 This page for your notes. 74 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 This page for your notes. Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 75 This page for your notes. 76 Pioneer Short Term Income Fund | Semiannual Report | 2/28/13 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: -------------------------------------------------------------------------------- PIMSS, Inc. 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) 2013 Pioneer Investments 19127-07-0413 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 10(a), 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 accountant's 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 registrant's accountant for services rendered to the registrant, and rendered to the registrant's 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 registrant's audit committee of the board of trustees has considered whether the provision of non-audit services that were rendered to the registrant's 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 registrants 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 I Investments in securities of unaffiliated issuers as of the close of the reporting period as set forth in 210.12- 12 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 registrants portfolio (Portfolio Manager). Also state each Portfolio Managers 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 registrants equity securities that is registered by the registrant pursuant to Section 12 of the Exchange Act (15 U.S.C. 781). Instruction to paragraph (a). Disclose all purchases covered by this Item, including purchases that do not satisfy the conditions of the safe harbor of Rule 10b-18 under the Exchange Act (17 CFR 240.10b-18), made in the period covered by the report. Provide disclosures covering repurchases made on a monthly basis. For example, if the reporting period began on January 16 and ended on July 15, the chart would show repurchases for the months from January 16 through February 15, February 16 through March 15, March 16 through April 15, April 16 through May 15, May 16 through June 15, and June 16 through July 15. 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 registrants board of directors, where those changes were implemented after the registrant last provided disclosure in response to the requirements of Item 7(d)(2)(ii)(G) 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 registrants board of directors since the registrant last provided disclosure in response to the requirements of Item 7(d)(2)(ii)(G) 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 officer or officers and principal financial officer or officers, or persons performing similar functions, about the effectiveness of the registrant's disclosure controls and procedures (as defined in Rule 30a-2(c) under the Act (17 CFR 270.30a-2(c))) based on their evaluation of these controls and procedures as of a date within 90 days of the filing date of the report that includes the disclosure required by this paragraph. The registrant's principal executive officer and principal financial officer have concluded that the registrant's disclosure controls and procedures are effective based on their evaluation of these controls and procedures as of a date within 90 days of the filing date of this report. (b) Disclose whether or not there were significant changes in the registrant's internal controls or in other factors that could significantly affect these controls subsequent to the date of their evaluation, including any corrective actions with regard to significant deficiencies and material weaknesses. 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. File the exhibits listed below as part of this Form. Letter or number the exhibits in the sequence indicated. (a) 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. (b) A separate certification for each principal executive officer and principal financial officer of the registrant as required by Rule 30a-2 under the Act (17 CFR 270.30a-2). 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/ John F. Cogan, Jr. John F. Cogan, Jr, President Date April 29, 2013 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/ John F. Cogan, Jr. John F. Cogan, Jr., President Date April 29, 2013 By (Signature and Title)* /s/ Mark Bradley Mark Bradley, Treasurer & Chief Accounting & Financial Officer Date April 29, 2013 * Print the name and title of each signing officer under his or her signature.