Pioneer High Yield Fund NCSRS Certified semi-annual shareholder report (management investment company)

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 811-09685

Pioneer High Yield 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, Amundi Asset 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: October 31, 2022

Date of reporting period: November 1, 2021 through April 30, 2022

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.

Pioneer High

Yield Fund

Semiannual Report | April 30, 2022

A: TAHYX

C: PYICX

R: TYHRX

Y: TYHYX

visit us: www.amundi.com/us

Pioneer High Yield Fund | Semiannual Report | 4/30/22 1

President’s Letter

Dear Shareholders,

For two years now, investors have faced unprecedented challenges, as the COVID-19 pandemic has not only dominated the headlines since March 2020, but has also led to significant changes in government and central-bank policies, both in the US and abroad, and affected the everyday lives of each of us. With 2022 now well underway, the situation, while improved, has continued to evolve.

Widespread distribution of the COVID-19 vaccines approved for emergency use in late 2020 led to a general decline in virus-related hospitalizations in the US and had a positive effect on overall market sentiment during most of the 2021 calendar year. The passage of two additional fiscal stimulus packages by US lawmakers in December 2020 and January 2021 also helped drive a strong market rally. Then, the late-2021 emergence of the highly infectious Omicron variant of the virus led to surges in cases and hospitalizations, especially outside of the US, but also in certain areas of this country. That development contributed to a slowdown in the global economic recovery, as some foreign governments reinstated strict virus-containment measures that had been relaxed after the rollout of the vaccines. Many of those renewed restrictions were lifted as case numbers again began to decline during the late-winter months, but it appears the possibility of further virus-containment measures could be with us for a while longer, given that occasional surges in new cases have continued to arise, particularly in non-US locations.

In the US, while performance of most asset classes, especially equities, was positive for the full 2021 calendar year, 2022, so far, has featured a less-friendly market environment. Volatility in the fixed-income markets has remained high and we have seen negative returns for most asset classes. Meanwhile, equity markets, both domestic and global, have experienced significant underperformance over the first several months of the year. Concerns over global supply chain issues, rising inflation, the enactment of less-accommodative monetary policies from the Federal Reserve System (Fed), and partisan debates in Washington, DC over future spending and tax policies, are among the many factors that have led to greater uncertainty and an increase in market volatility. In addition, Russia's recent incursion into Ukraine has resulted in even greater market volatility, as economic sanctions placed on Russia by many Western countries have exacerbated the existing supply-chain issues and helped drive energy prices, including gas prices, to very high levels.

In our view, the long-term impact on the global economy from COVID-19, while currently unknown, is likely to be considerable, as it is clear that several industries have already felt greater effects than others, and could continue to struggle for quite some time. Of course, geopolitical concerns, whether they are related to the conflict in Ukraine or other crises in different areas of the globe, can always have an effect on the markets, and so our investment teams will remain vigilant and continue to monitor the geopolitical landscape.

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At the outset of the pandemic, we temporarily closed our offices and instituted a work-from-home policy, but have since re-opened our US locations. However, we have been maintaining all the necessary precautions, which at times may have us working more remotely than in person in order to ensure a safe working environment as new variants of the COVID-19 virus continue to arise and spread. I am proud of the careful planning that has taken place. Throughout the pandemic, our business has continued to operate without any disruption, and we all look forward to regaining a bit of normalcy after so many months of remote working.

Since 1928, Amundi US’s investment process has been built on a foundation of fundamental research and active management, principles which have guided our investment decisions for more than 90 years. We believe active management – that is, making active investment decisions – can help mitigate the risks during periods of market volatility.

At Amundi US, active management begins with our own fundamental, bottom-up research process. Our team of dedicated research analysts and portfolio managers analyzes each security under consideration, communicating frequently with the management teams of the companies and other entities issuing the securities, and working together to identify those securities that best meet our investment criteria for our family of funds. Our risk management approach begins with each and every security, as we strive to carefully understand the potential opportunity, while considering any and all risk factors.

Today, as investors, we have many options. It is our view that active management can serve shareholders well, not only when markets are thriving, but also during periods of market stress.

As you consider your long-term investment goals, we encourage you to work with your financial professional to develop an investment plan that paves the way for you to pursue both your short-term and long-term goals.

We greatly appreciate the trust you have placed in us and look forward to continuing to serve you in the future.

Sincerely,

Lisa M. Jones

Head of the Americas, President and CEO of US

Amundi Asset Management US, Inc.

June 2022

Any information in this shareowner report regarding market or economic trends or the factors influencing the Fund’s historical or future performance are statements of opinion as of the date of this report. Past performance is no guarantee of future results.

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Portfolio Management Discussion | 4/30/22

In the following interview, Andrew Feltus, Ken Monaghan, and Matt Shulkin discuss the factors that influenced the performance of Pioneer High Yield Fund during the six-month period ended April 30, 2022. Mr. Feltus, Managing Director, Co-Director of High Yield, and a portfolio manager at Amundi Asset Management US, Inc. (Amundi US), is responsible for the day-to-day management of the Fund, along with Mr. Monaghan, Managing Director, Co-Director of High Yield, and a portfolio manager at Amundi US, and Mr. Shulkin, a senior vice president and a portfolio manager at Amundi US.

How did the Fund perform during the six-month period ended April 30, 2022?

Pioneer High Yield Fund’s Class A shares returned -5.93% at net asset value during the six-month period ended April 30, 2022, while the Fund’s primary benchmark, the ICE Bank of America (ICE BofA) US High Yield Index (the high-yield index), returned -7.22%, and the Fund’s secondary benchmark, the ICE BofA All-Convertibles Speculative Quality Index, returned -13.99%. During the same period, the average return of the 694 mutual funds in Morningstar’s High Yield Bond Funds category was -6.47%.

Could you please describe the market environment for high-yield bonds during the six-month period ended April 30, 2022?

As the period opened in October 2021, the market appeared to shrug off concerns over the prospect of tighter Federal Reserve (Fed) monetary policy and the rapidly spreading Omicron variant of COVID-19. As a result, we saw solid performance for credit-sensitive categories of the fixed-income market, such as high-yield securities, through the end of the calendar year. However, the first quarter of 2022 saw market sentiment dominated by increased geopolitical tensions, a worsening growth/inflation mix arising from a spike in commodity prices, and the prospect of rising interest rates due to changing policies of many central banks, which led to losses across most asset classes within fixed income.

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Russia’s invasion of Ukraine in late February, together with US and European sanctions on Russia, led to sharp increases in energy, metals, and food prices, adding downside risk to real economic growth and adding upside risk to inflation. In addition, another round of lockdowns in China in the wake of increasing COVID-19 infection rates exacerbated the existing supply chain disruptions and raised concerns about further risks to global economic growth.

At its mid-March meeting, the Fed’s Open Market Committee (FOMC) raised the federal funds rate target range by a quarter-point, to 0.25% - 0.50%, and indicated that further increases in the benchmark overnight lending rate would follow rapidly. The Fed also formally ended its pandemic-era quantitative easing program and signaled it would soon begin reducing its holdings of Treasury securities and agency mortgage-backed securities (MBS) by reinvesting only part of the proceeds from maturing securities.

Treasury yields moved sharply higher as the outlook for inflation and Fed policy shifted in the first quarter of 2022, resulting in weak fixed-income returns for the full six-month period. High-yield corporate issues, which have tended to be less-interest rate-sensitive than other assets, outperformed their investment-grade counterparts over the period. Sectors that had felt the worst effects of the COVID-19 crisis, such as energy and air transportation, outperformed other sectors as investors anticipated a further economic reopening. In contrast, sectors that were more “up in quality” and thus highly sensitive to interest-rate changes, and which had been relatively insulated from the effects of COVID-19, underperformed for the period. These included telecommunications and food & drug retail.

With respect to ratings categories, lower-quality securities outperformed higher quality.

Which of your investment strategies aided or detracted from the Fund’s performance relative to the benchmark high-yield index during the six-month period ended April 30, 2022?

The Fund’s asset allocations and security selection results both aided benchmark-relative performance over the six-month period.

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The Fund was well positioned in sectors that have been benefiting from the economic reopening, including energy and transportation. Within energy, positive contributions to relative returns were highlighted by a portfolio position in Baytex Energy, an exploration-and-production company focused on oil operations in Western Canada and the Eagle Ford field in Texas. Holdings of the bonds of Shelf Drilling, an operator of shallow water jack-up drilling rigs outside of the US, also provided a boost to the Fund’s benchmark-relative results. Within transportation, a position in Mexican airline Grupo Aeromexico contributed positively to the Fund’s relative performance. Elsewhere, portfolio positions in the bonds of ambulatory surgical facility operator Surgery Center Holdings was another notable positive contributor to the Fund’s relative returns for the period.

With regard to asset allocation, the Fund’s exposures to index-based credit-default-swap contracts (index-swap contracts), and the portfolio’s cash position, aided relative performance for the period. During the period, we sought to add some protection to the portfolio through the use of the index-swap contracts, as high-yield credit spreads narrowed to pre-pandemic levels. Meanwhile, we held cash in the portfolio to help ensure adequate liquidity. (Credit spreads are commonly defined as the differences in yield between Treasuries and other types of fixed-income securities with similar maturities.)

One of the sector exposures that weighed on the Fund’s benchmark-relative performance during the period was leisure, as some portfolio positions in theme park and cruise line companies underperformed. An off-benchmark allocation to convertible bonds also detracted from the Fund’s relative returns. Most notable among those holdings were underperforming positions in Wells Fargo and the convertible bonds of sports betting company DraftKings. The Fund’s exposure to Diebold Nixdorf, a manufacturer of automated teller machines (ATMs) and retail point-of-sale solutions, generated weak returns during the period, as did the portfolio’s holdings of Cornerstone Building Brands, one of the largest manufacturers of exterior building products in North America.

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Did the Fund have any exposure to derivative securities during the six-month period ended April 30, 2022? If so, did the derivatives have any effect on the Fund’s performance?

Yes, as noted and described earlier, the Fund’s index-based credit-default-swap positions aided benchmark-relative performance over the six-month period.

Did the Fund’s distributions* to shareholders change during the six-month period ended April 30, 2022?

The Fund’s monthly distribution rate declined over the six-month period, as high-yield spreads narrowed fairly significantly (to pre-pandemic levels).

What is your assessment of the current climate for high yield investing?

We believe it will be difficult for the Fed to achieve a “soft” economic landing as it works to try to bring inflation back down to its stated long-term target of 2% (year-over-year, core personal consumption expenditure inflation). To the extent that domestic core inflation readouts may not decline as much as the Fed expects throughout 2022, the US central bank will then face a tough decision. Our expectation is that the Fed will have to decide whether to continue to increase the federal funds target range to well above the 3.0% peak priced in by the market, at the risk of causing a recession, or increase the stated inflation target from 2% to 2.5%, or even to 3.0%; or, perhaps, opt for a little bit of each approach. The potential benefit of a higher inflation target, in our view, is that the Fed could then raise the “neutral” federal funds rate target range and thus provide more room to eventually cut rates before hitting zero if, and when, the next recession arrives. We believe the Fed may deem such a change as the lesser of two evils, but if so, it will have to message that change very carefully in order to maintain its long-term credibility.

Distributions are not guaranteed.

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Although we are wary of interest-rate exposure, we note that current Treasury yields anticipate higher short-term rates. Fed officials, our management team, and other investors, will be parsing the monthly inflation releases to gauge just how persistent inflation turns out to be. We also will be examining economic releases to understand how well the economy is withstanding higher interest rates.

We remain positive on the short-term fundamental outlook for high-yield corporates, given a backdrop of low defaults, still-accommodative (for now) monetary policy, and continued global demand for yield among investors. Above-trend economic growth and higher inflation have usually been good for corporate cash flows, and may help keep high-yield default rates low. Likewise, consumers have remained in decent shape, given low unemployment, rising wages, and higher net worth’s driven in significant part by the housing market.

With that said, we believe it is likely that markets will remain volatile until there is greater clarity on the path of inflation and short-term interest rates, and so we expect security selection to be a larger contributor to returns, as opposed to pure “beta” exposures. (Beta measures an investment’s sensitivity to market movements in relation to an index.)

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Please refer to the Schedule of Investments on pages 19–38 for a full listing of Fund securities.

All investments are subject to risk, including the possible loss of principal. In the past several years, financial markets have experienced increased volatility and heightened uncertainty. The market prices of securities may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic, political, or regulatory conditions, recessions, inflation, changes in interest or currency rates, lack of liquidity in the bond markets, the spread of infectious illness or other public health issues, armed conflict including Russia’s military invasion of Ukraine, sanctions against Russia, other nations or individuals or companies and possible countermeasures, or adverse investor sentiment. These conditions may continue, recur, worsen or spread.

Investments in high-yield or lower-rated securities are subject to greater-than-average price volatility, illiquidity and possibility of default.

When interest rates rise, the prices of fixed-income securities held by the Fund will generally fall. Conversely, when interest rates fall, the prices of fixed-income securities held by the Fund will generally rise.

The Fund’s investments, payment obligations and financing terms may be based on floating rates, such as LIBOR (London Interbank Offered Rate). Plans are underway to phase out the use of LIBOR. There remains uncertainty regarding the nature of any replacement rate and the impact of the transition from LIBOR on the Fund, issuers of instruments in which the Fund invests, and financial markets generally.

Investments in the Fund are subject to possible loss due to the financial failure of issuers of underlying securities and their inability to meet their debt obligations.

Prepayment risk is the chance that an issuer may exercise its right to prepay its security, if falling interest rates prompt the issuer to do so. Forced to reinvest the unanticipated proceeds at lower interest rates, the Fund would experience a decline in income and lose the opportunity for additional price appreciation.

The Fund may invest in mortgage-backed securities, which during times of fluctuating interest rates may increase or decrease more than other fixed-income securities. Mortgage-backed securities are also subject to prepayments.

The Fund may use derivatives, such as options, futures, inverse floating rate obligations, swaps, and others, which can be illiquid, may disproportionately increase losses, and have a potentially large impact on Fund performance. Derivatives may have a leveraging effect on the Fund.

At times, the Fund’s investments may represent industries or industry sectors that are interrelated or have common risks, making the Fund more susceptible to any economic, political, or regulatory developments or other risks affecting those industries and sectors.

These risks may increase share price volatility.

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Before investing, consider the product’s investment objectives, risks, charges and expenses. Contact your advisor or Amundi for a prospectus or summary prospectus containing this information. Read it carefully.

Any information in this shareholder report regarding market or economic trends or the factors influencing the Fund’s historical or future performance are statements of opinion as of the date of this report. Past performance is no guarantee of future results.

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Portfolio Summary | 4/30/22

Portfolio Diversification

(As a percentage of total investments)*

10 Largest Holdings
(As a percentage of total investments)*
1.	U.S. Treasury Bills, 5/10/22	2.71%
2.	Baytex Energy Corp., 8.75%, 4/1/27 (144A)	1.12
3.	Cleveland-Cliffs, Inc., 6.75%, 3/15/26 (144A)	1.01
4.	Artera Services LLC, 9.033%, 12/4/25 (144A)	0.95
5.	VistaJet Malta Finance Plc/XO Management Holding, Inc.,
	6.375%, 2/1/30 (144A)	0.93
6.	Mercer International, Inc., 5.125%, 2/1/29	0.83
7.	JB Poindexter & Co., Inc., 7.125%, 4/15/26 (144A)	0.82
8.	Harvest Midstream I LP, 7.50%, 9/1/28 (144A)	0.81
9.	Energean Plc, 6.50%, 4/30/27 (144A)	0.78
10.	Minerva Merger Sub, Inc., 6.50%, 2/15/30 (144A)	0.78

Excludes short-term investments and all derivative contracts except for options purchased. The Fund is actively managed, and current holdings may be different. The holdings listed should not be considered recommendations to buy or sell any securities.

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Prices and Distributions | 4/30/22

Net Asset Value per Share

Class	4/30/22	10/31/21
A	$ 8.89	$ 9.64
C	$ 9.08	$ 9.84
R	$10.07	$10.93
Y	$ 8.90	$ 9.65

Distributions per Share: 11/1/21–4/30/22

	Net Investment	Short-Term	Long-Term
Class	Income	Capital Gains	Capital Gains
A	$0.1851	$ —	$ —
C	$0.1478	$ —	$ —
R	$0.1843	$ —	$ —
Y	$0.1971	$ —	$ —

Index Definitions

The ICE Bank of America (BofA) U.S. High Yield Index is an unmanaged, commonly accepted measure of the performance of high-yield securities. The ICE Bank of America (BofA) All Convertibles Speculative Quality Index is an unmanaged index of high-yield U.S. convertible securities. Index returns are calculated monthly, assume reinvestment of dividends and, unlike fund returns, do not reflect any fees, expense or sales charges. It is not possible to invest directly in an index.

The indices defined here pertain to the “Value of $10,000 Investment” and the “Value of $5 Million Investment” charts on pages 13–16.

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Performance Update | 4/30/22

Class A Shares

Investment Returns

The mountain chart on the right shows the change in value of a $10,000 investment made in Class A shares of Pioneer High Yield Fund at public offering price during the periods shown, compared to that of the ICE Bank of America (BofA) U.S. High Yield Index and the ICE BofA All Convertibles Speculative Quality Index.

Average Annual Total Returns
(As of April 30, 2022)
			ICE	ICE
	Net	Public	BofA	BofA All
	Asset	Offering	U.S. High	Convertibles
	Value	Price	Yield	Speculative
Period	(NAV)	(POP)	Index	Quality Index
10 years	4.57%	4.10%	5.20%	16.30%
5 years	3.07	2.12	3.56	23.33
1 year	-3.99	-8.27	-4.96	-8.10

Expense Ratio
(Per prospectus dated March 1, 2022)
Gross	Net
1.20%	1.10%

Call 1-800-225-6292 or visit www.amundi.com/us for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted.

The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost.

NAV results represent the percent change in net asset value per share. POP returns reflect deduction of maximum 4.50% sales charge. NAV 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 the contractual expense limitation in effect through March 1, 2023 for Class A shares. There can be no assurance that Amundi US will extend the expense limitation beyond such time. Please see the prospectus and financial statements for more information.

The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares.

Please refer to the financial highlights for more current expense ratios.

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Performance Update | 4/30/22

Class C Shares

Investment Returns

The mountain chart on the right shows the change in value of a $10,000 investment made in Class C shares of Pioneer High Yield Fund during the periods shown, compared to that of the ICE Bank of America (BofA) U.S. High Yield Index and the ICE BofA All Convertibles Speculative Quality Index.

Average Annual Total Returns
(As of April 30, 2022)
			ICE	ICE
			BofA	BofA All
			U.S. High	Convertibles
	If	If	Yield	Speculative
Period	Held	Redeemed	Index	Quality Index
10 years	3.80%	3.80%	5.20%	16.30%
5 years	2.26	2.26	3.56	23.33
1 year	-4.88	-5.80	-4.96	-8.10

Expense Ratio

(Per prospectus dated March 1, 2022)

Gross

1.98%

Call 1-800-225-6292 or visit www.amundi.com/us for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted.

Class C shares held for less than one year are subject to a 1% contingent deferred sales charge (CDSC). “If Held” results represent the percent change in net asset value per share. “If Redeemed” returns reflect deduction of the CDSC for the one-year period, assuming a complete redemption of shares at the last price calculated on the last business day of the period, and no CDSC for the five- and 10-year periods. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ.

The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares.

Please refer to the financial highlights for a more current expense ratio.

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Performance Update | 4/30/22

Class R Shares

Investment Returns

The mountain chart on the right shows the change in value of a $10,000 investment made in Class R shares of Pioneer High Yield Fund during the periods shown, compared to that of the ICE Bank of America (BofA) U.S.

High Yield Index and the ICE BofA All Convertibles Speculative Quality Index.

Average Annual Total Returns
(As of April 30, 2022)
		ICE	ICE
	Net	BofA	BofA All
	Asset	U.S. High	Convertibles
	Value	Yield	Speculative
Period	(NAV)	Index	Quality Index
10 years	4.17%	5.20%	16.30%
5 years	2.62	3.56	23.33
1 year	-4.63	-4.96	-8.10

Expense Ratio

(Per prospectus dated March 1, 2022)

Gross

1.59%

Call 1-800-225-6292 or visit www.amundi.com/us for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted.

Class R shares are not subject to sales charges and are available for limited groups of eligible investors, including institutional investors. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ.

The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares.

Please refer to the financial highlights for a more current expense ratio.

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Performance Update | 4/30/22

Class Y Shares

Investment Returns

The mountain chart on the right shows the change in value of a $5 million investment made in Class Y shares of Pioneer High Yield Fund, during the periods shown, compared to that of the ICE Bank of America (BofA) U.S. High Yield Index and the ICE BofA All Convertibles Speculative Quality Index.

Average Annual Total Returns
(As of April 30, 2022)
		ICE	ICE
	Net	BofA	BofA All
	Asset	U.S. High	Convertibles
	Value	Yield	Speculative
Period	(NAV)	Index	Quality Index
10 years	4.88%	5.20%	16.30%
5 years	3.35	3.56	23.33
1 year	-3.74	-4.96	-8.10

Expense Ratio
(Per prospectus dated March 1, 2022)
Gross	Net
0.90%	0.85%

Call 1-800-225-6292 or visit www.amundi.com/us for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted.

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.

The net expense ratio reflects the contractual expense limitation in effect through March 1, 2023 for Class Y shares. There can be no assurance that Amundi US will extend the expense limitation beyond such time. Please see the prospectus and financial statements for more information.

The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares.

Please refer to the financial highlights for more current expense ratios.

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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:

Divide your account value by $1,000

Example: an $8,600 account value ÷ $1,000 = 8.6

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 High Yield Fund

Based on actual returns from November 1, 2021 through April 30, 2022.


Share Class	A	C	R	Y
Beginning Account	$1,000.00	$1,000.00	$1,000.00	$1,000.00
Value on 11/1/21
Ending Account	$940.70	$936.20	$937.50	$941.90
Value (after expenses)
on 4/30/22
Expenses Paid	$5.29	$9.36	$7.54	$4.09
During Period*

Expenses are equal to the Fund’s annualized expense ratio of 1.10%, 1.95%, 1.57%, and 0.85% for Class A, Class C, Class R, 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).

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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 High Yield Fund

Based on a hypothetical 5% return per year before expenses, reflecting the period from November 1, 2021 through April 30, 2022.

Share Class	A	C	R	Y
Beginning Account	$1,000.00	$1,000.00	$1,000.00	$1,000.00
Value on 11/1/21
Ending Account	$1,019.34	$1,015.12	$1,017.01	$1,020.58
Value (after expenses)
on 4/30/22
Expenses Paid	$5.51	$9.74	$7.85	$4.26
During Period*

18 Pioneer High Yield Fund | Semiannual Report | 4/30/22

Table of Contents

Schedule of Investments | 4/30/22

(unaudited)

Principal
Amount
USD ($)		Value
	UNAFFILIATED ISSUERS — 99.0%
	SENIOR SECURED FLOATING RATE LOAN
	*INTERESTS — 2.6% of Net Assets(a)**
	Airlines — 0.3%
1,585,000	LATAM Airlines Group S.A., Tranche A Facility,
	8.234% (Term SOFR + 750 bps), 8/8/22	$ 1,596,491
	Total Airlines	$ 1,596,491
	Auto Parts & Equipment — 0.4%
2,307,084(b)	First Brands Group LLC, First Lien 2021 Term Loan,
	6.00% (Term SOFR + 500 bps), 3/30/27	$ 2,306,122
	Total Auto Parts & Equipment	$ 2,306,122
	Gambling (Non-Hotel) — 0.5%
2,437,620	Enterprise Development Authority, Term B Loan,
	5.014% (LIBOR + 425 bps), 2/28/28	$ 2,432,543
	Total Gambling (Non-Hotel)	$ 2,432,543
	Human Resources — 0.3%
1,683,373	Team Health Holdings, Inc., Extended Term Loan,
	6.25% (Term SOFR + 525 bps), 3/2/27	$ 1,592,190
	Total Human Resources	$ 1,592,190
	Medical-Hospitals — 0.1%
415,800	Surgery Center Holdings, Inc., 2021 New Term Loan,
	4.50% (LIBOR + 375 bps), 8/31/26	$ 412,566
	Total Medical-Hospitals	$ 412,566
	Metal Processors & Fabrication — 0.3%
1,781,050	Grinding Media Inc. (Molycop Ltd.), First Lien Initial
	Term Loan, 4.796% (LIBOR + 400 bps), 10/12/28	$ 1,747,655
	Total Metal Processors & Fabrication	$ 1,747,655
	Oil-Field Services — 0.7%
3,880,000	ProFrac Holdings II, LLC, Term Loan, 9.603%
	(Term SOFR + 850 bps), 3/4/25	$ 3,821,800
	Total Oil-Field Services	$ 3,821,800
	TOTAL SENIOR SECURED FLOATING RATE
	LOAN INTERESTS
	(Cost $13,755,465)	$ 13,909,367

The accompanying notes are an integral part of these financial statements.

Pioneer High Yield Fund | Semiannual Report | 4/30/22 19

Table of Contents

Schedule of Investments | 4/30/22

(unaudited) (continued)


Shares		Value
	COMMON STOCKS — 0.4% of Net Assets
	Airlines — 0.3%
90,545	Grupo Aeromexico SAB de CV	$ 1,598,675
	Total Airlines	$ 1,598,675
	Oil, Gas & Consumable Fuels — 0.1%
23(c)	Amplify Energy Corp.	$ 154
6,967,063(c)	Ascent CNR Corp.	696,706
	Total Oil, Gas & Consumable Fuels	$ 696,860
	TOTAL COMMON STOCKS
	(Cost $1,645,596)	$ 2,295,535

Principal
Amount
USD ($)
	COLLATERALIZED MORTGAGE
	OBLIGATIONS — 0.0%† of Net Assets
185,399	Global Mortgage Securitization, Ltd., Series 2004-A,
	Class B1, 5.25%, 11/25/32 (144A)	$ 131,378
	TOTAL COLLATERALIZED MORTGAGE OBLIGATIONS
	(Cost $181,503)	$ 131,378
	COMMERCIAL MORTGAGE-BACKED
	SECURITY — 0.2% of Net Assets
900,000	Med Trust, Series 2021-MDLN, Class G, 5.805%
	(1 Month USD LIBOR + 525 bps), 11/15/38 (144A)	$ 875,876
	TOTAL COMMERCIAL MORTGAGE-BACKED SECURITY
	(Cost $900,000)	$ 875,876
	CONVERTIBLE CORPORATE BONDS — 3.4% of
	Net Assets
	Airlines — 0.9%
1,437,000	Air Canada, 4.00%, 7/1/25	$ 1,976,593
2,986,000	Spirit Airlines, Inc., 1.00%, 5/15/26	2,712,781
	Total Airlines	$ 4,689,374
	Biotechnology — 0.4%
730,000	Insmed, Inc., 0.75%, 6/1/28	$ 685,105
1,244,000	Insmed, Inc., 1.75%, 1/15/25	1,214,908
	Total Biotechnology	$ 1,900,013
	Commercial Services — 0.0%†
50	Macquarie Infrastructure Holdings LLC, 2.00%, 10/1/23	$ 49
	Total Commercial Services	$ 49
	Energy-Alternate Sources — 0.3%
1,619,000(d)	Enphase Energy, Inc., 3/1/28	$ 1,539,669
	Total Energy-Alternate Sources	$ 1,539,669

The accompanying notes are an integral part of these financial statements.

20 Pioneer High Yield Fund | Semiannual Report | 4/30/22

Table of Contents

Principal
Amount
USD ($)		Value
	Entertainment — 0.5%
1,974,000(d)	DraftKings Holdings, Inc., 3/15/28	$ 1,311,723
1,369,000	IMAX Corp., 0.50%, 4/1/26	1,216,357
	Total Entertainment	$ 2,528,080
	Internet — 0.0%†
210,000	Perficient, Inc., 0.125%, 11/15/26 (144A)	$ 180,285
	Total Internet	$ 180,285
	Pharmaceuticals — 0.5%
2,035,000	Revance Therapeutics, Inc., 1.75%, 2/15/27	$ 1,774,266
2,122,000	Tricida, Inc., 3.50%, 5/15/27	1,099,408
	Total Pharmaceuticals	$ 2,873,674
	REITs — 0.2%
971,000	Summit Hotel Properties, Inc., 1.50%, 2/15/26	$ 993,819
	Total REITs	$ 993,819
	Software — 0.6%
1,100,000	Bentley Systems, Inc., 0.375%, 7/1/27 (144A)	$ 932,250
855,000	Jamf Holding Corp., 0.125%, 9/1/26 (144A)	789,806
1,450,000	Verint Systems, Inc., 0.25%, 4/15/26	1,528,300
	Total Software	$ 3,250,356
	TOTAL CONVERTIBLE CORPORATE BONDS
	(Cost $19,933,374)	$ 17,955,319
	CORPORATE BONDS — 86.9% of Net Assets
	Advertising — 2.2%
300,000	Clear Channel International BV, 6.625%, 8/1/25 (144A)	$ 303,168
2,400,000	Clear Channel Outdoor Holdings, Inc., 7.50%,
	6/1/29 (144A)	2,264,880
1,430,000	Clear Channel Outdoor Holdings, Inc., 7.75%,
	4/15/28 (144A)	1,347,775
1,080,000	Outfront Media Capital LLC/Outfront Media Capital
	Corp., 4.25%, 1/15/29 (144A)	939,600
975,000	Outfront Media Capital LLC/Outfront Media Capital
	Corp., 6.25%, 6/15/25 (144A)	987,188
3,915,000	Stagwell Global LLC, 5.625%, 8/15/29 (144A)	3,456,749
2,512,000	Summer BC Bidco B LLC, 5.50%, 10/31/26 (144A)	2,412,022
	Total Advertising	$ 11,711,382
	Aerospace & Defense — 0.9%
1,545,000	Bombardier, Inc., 7.125%, 6/15/26 (144A)	$ 1,421,400
3,410,000	Bombardier, Inc., 7.875%, 4/15/27 (144A)	3,176,654
	Total Aerospace & Defense	$ 4,598,054

The accompanying notes are an integral part of these financial statements.

Pioneer High Yield Fund | Semiannual Report | 4/30/22 21

Table of Contents

Schedule of Investments | 4/30/22

(unaudited) (continued)

Principal
Amount
USD ($)		Value
	Airlines — 0.4%
630,000	American Airlines 2021-1 Class B Pass Through Trust,
	3.95%, 7/11/30	$ 568,926
955,000	American Airlines, Inc./AAdvantage Loyalty IP, Ltd.,
	5.50%, 4/20/26 (144A)	946,644
795,000	American Airlines, Inc./AAdvantage Loyalty IP, Ltd.,
	5.75%, 4/20/29 (144A)	766,042
	Total Airlines	$ 2,281,612
	Auto Manufacturers — 3.0%
950,000	Ford Motor Credit Co. LLC, 2.70%, 8/10/26	$ 846,906
1,900,000	Ford Motor Credit Co. LLC, 3.625%, 6/17/31	1,579,375
3,399,000	Ford Motor Credit Co. LLC, 4.00%, 11/13/30	2,948,632
3,110,000	Ford Motor Credit Co. LLC, 4.125%, 8/17/27	2,883,126
1,635,000	Ford Motor Credit Co. LLC, 4.542%, 8/1/26	1,563,469
200,000	Ford Motor Credit Co. LLC, 4.95%, 5/28/27	194,782
1,825,000	Ford Motor Credit Co. LLC, 5.113%, 5/3/29	1,731,469
4,221,000	JB Poindexter & Co., Inc., 7.125%, 4/15/26 (144A)	4,228,471
	Total Auto Manufacturers	$ 15,976,230
	Auto Parts & Equipment — 0.6%
3,198,000	Dealer Tire LLC/DT Issuer LLC, 8.00%, 2/1/28 (144A)	$ 3,128,412
	Total Auto Parts & Equipment	$ 3,128,412
	Banks — 0.5%
250,000	Freedom Mortgage Corp., 6.625%, 1/15/27 (144A)	$ 216,375
1,896,000	Freedom Mortgage Corp., 8.125%, 11/15/24 (144A)	1,836,437
736,000	Freedom Mortgage Corp., 8.25%, 4/15/25 (144A)	706,560
	Total Banks	$ 2,759,372
	Biotechnology — 0.5%
3,040,000	Grifols Escrow Issuer SA, 4.75%, 10/15/28 (144A)	$ 2,774,000
	Total Biotechnology	$ 2,774,000
	Building Materials — 1.8%
2,461,000	Builders FirstSource, Inc., 4.25%, 2/1/32 (144A)	$ 2,101,079
270,000	Builders FirstSource, Inc., 5.00%, 3/1/30 (144A)	249,750
3,035,000	Cornerstone Building Brands, Inc., 6.125%,
	1/15/29 (144A)	2,525,272
2,944,000	CP Atlas Buyer, Inc., 7.00%, 12/1/28 (144A)	2,458,240
1,217,000	Koppers, Inc., 6.00%, 2/15/25 (144A)	1,177,447
1,435,000	Oscar AcquisitionCo LLC/Oscar Finance, Inc.,
	9.50%, 4/15/30 (144A)	1,307,213
	Total Building Materials	$ 9,819,001

The accompanying notes are an integral part of these financial statements.

22 Pioneer High Yield Fund | Semiannual Report | 4/30/22

Table of Contents

Principal
Amount
USD ($)		Value
	Chemicals — 2.1%
2,868,000	LSF11 A5 HoldCo LLC, 6.625%, 10/15/29 (144A)	$ 2,495,160
2,819,000	Olin Corp., 5.00%, 2/1/30	2,670,157
1,445,000	SCIL IV LLC/SCIL USA Holdings LLC, 5.375%,
	11/1/26 (144A)	1,318,562
2,880,000	Trinseo Materials Operating SCA/Trinseo Materials
	Finance, Inc., 5.125%, 4/1/29 (144A)	2,534,400
2,505,000	Tronox, Inc., 4.625%, 3/15/29 (144A)	2,241,975
	Total Chemicals	$ 11,260,254
	Commercial Services — 5.2%
590,000	Allied Universal Holdco LLC/Allied Universal Finance
	Corp., 6.00%, 6/1/29 (144A)	$ 483,800
1,410,000	Allied Universal Holdco LLC/Allied Universal Finance
	Corp., 6.625%, 7/15/26 (144A)	1,360,650
1,025,000	Allied Universal Holdco LLC/Allied Universal Finance
	Corp./Atlas Luxco 4 S.a.r.l., 4.625%, 6/1/28
	(144A)	907,125
1,924,000	APX Group, Inc., 5.75%, 7/15/29 (144A)	1,576,429
1,710,000	APX Group, Inc., 6.75%, 2/15/27 (144A)	1,695,038
2,030,000	Brink’s Co., 5.50%, 7/15/25 (144A)	2,036,090
2,855,000	CoreLogic, Inc., 4.50%, 5/1/28 (144A)	2,529,616
295,000	Garda World Security Corp., 4.625%, 2/15/27 (144A)	267,713
3,008,000	Garda World Security Corp., 9.50%, 11/1/27 (144A)	2,955,360
1,155,000	HealthEquity, Inc., 4.50%, 10/1/29 (144A)	1,055,381
1,470,000	NESCO Holdings II, Inc., 5.50%, 4/15/29 (144A)	1,385,475
2,755,000	PECF USS Intermediate Holding III Corp., 8.00%,
	11/15/29 (144A)	2,551,791
975,000	Prime Security Services Borrower LLC/Prime Finance,
	Inc., 5.25%, 4/15/24 (144A)	973,781
1,870,000	Prime Security Services Borrower LLC/Prime Finance,
	Inc., 5.75%, 4/15/26 (144A)	1,792,862
4,165,000	Prime Security Services Borrower LLC/Prime Finance,
	Inc., 6.25%, 1/15/28 (144A)	3,733,298
2,279,000	Sotheby’s, 7.375%, 10/15/27 (144A)	2,244,815
	Total Commercial Services	$ 27,549,224
	Computers — 1.1%
330,000	Diebold Nixdorf, Inc., 8.50%, 4/15/24	$ 214,500
2,605,000	Diebold Nixdorf, Inc., 9.375%, 7/15/25 (144A)	2,280,704
1,435,000	KBR, Inc., 4.75%, 9/30/28 (144A)	1,352,487
1,275,000	NCR Corp., 5.00%, 10/1/28 (144A)	1,176,902
635,000	NCR Corp., 5.25%, 10/1/30 (144A)	600,075
	Total Computers	$ 5,624,668

The accompanying notes are an integral part of these financial statements.

Pioneer High Yield Fund | Semiannual Report | 4/30/22 23

Table of Contents

Schedule of Investments | 4/30/22

(unaudited) (continued)

Principal
Amount
USD ($)		Value
	Cosmetics/Personal Care — 0.8%
3,080,000	Edgewell Personal Care Co., 5.50%, 6/1/28 (144A)	$ 2,979,900
1,555,000	Natura &Co. Luxembourg Holdings S.a.r.l., 6.00%,
	4/19/29 (144A)	1,509,656
	Total Cosmetics/Personal Care	$ 4,489,556
	Diversified Financial Services — 4.0%
3,302,050(e)	Avation Capital SA, 8.25% (9.00% PIK or 8.25% Cash),
	10/31/26 (144A)	$ 2,741,264
2,360,000	Bread Financial Holdings Inc., 4.75%, 12/15/24 (144A)	2,289,200
3,425,466(e)	Global Aircraft Leasing Co., Ltd., 6.50% (7.25% PIK or
	6.50% Cash), 9/15/24 (144A)	2,954,396
3,538,000	Provident Funding Associates LP/PFG Finance Corp.,
	6.375%, 6/15/25 (144A)	3,471,662
1,628,000	United Wholesale Mortgage LLC, 5.50%,
	4/15/29 (144A)	1,351,240
2,885,000	United Wholesale Mortgage LLC, 5.75%,
	6/15/27 (144A)	2,502,737
5,505,000	VistaJet Malta Finance Plc/XO Management Holding,
	Inc., 6.375%, 2/1/30 (144A)	4,816,875
1,035,000	VistaJet Malta Finance Plc/XO Management Holding,
	Inc., 7.875%, 5/1/27 (144A)	973,625
	Total Diversified Financial Services	$ 21,100,999
	Electric — 2.3%
875,000	Calpine Corp., 4.625%, 2/1/29 (144A)	$ 763,438
561,000	Calpine Corp., 5.25%, 6/1/26 (144A)	553,988
1,640,000	Clearway Energy Operating LLC, 3.75%,
	2/15/31 (144A)	1,410,400
850,000	Clearway Energy Operating LLC, 3.75%,
	1/15/32 (144A)	720,375
940,000	Leeward Renewable Energy Operations LLC, 4.25%,
	7/1/29 (144A)	841,300
915,000	NRG Energy, Inc., 3.375%, 2/15/29 (144A)	775,462
1,315,000	NRG Energy, Inc., 3.625%, 2/15/31 (144A)	1,094,737
2,675,000	NRG Energy, Inc., 3.875%, 2/15/32 (144A)	2,232,943
177,466	NSG Holdings LLC/NSG Holdings, Inc., 7.75%,
	12/15/25 (144A)	181,459
1,075,000	Vistra Operations Co. LLC, 4.375%, 5/1/29 (144A)	975,541
2,852,000	Vistra Operations Co. LLC, 5.625%, 2/15/27 (144A)	2,809,220
	Total Electric	$ 12,358,863
Electrical Components & Equipments — 0.7%
1,800,000	Energizer Holdings, Inc., 4.75%, 6/15/28 (144A)	$ 1,582,596
985,000	Energizer Holdings, Inc., 6.50%, 12/31/27 (144A)	945,600
1,390,000	WESCO Distribution, Inc., 7.125%, 6/15/25 (144A)	1,443,862
	Total Electrical Components & Equipments	$ 3,972,058

The accompanying notes are an integral part of these financial statements.

24 Pioneer High Yield Fund | Semiannual Report | 4/30/22

Table of Contents

Principal
Amount
USD ($)		Value
	Electronics — 0.9%
2,034,000	Atkore, Inc., 4.25%, 6/1/31 (144A)	$ 1,800,090
1,665,000	II-VI, Inc., 5.00%, 12/15/29 (144A)	1,560,938
795,000	Sensata Technologies, Inc., 3.75%, 2/15/31 (144A)	672,204
615,000	TTM Technologies, Inc., 4.00%, 3/1/29 (144A)	538,125
	Total Electronics	$ 4,571,357
	Energy-Alternate Sources — 0.6%
475,000	Atlantica Sustainable Infrastructure Plc, 4.125%,
	6/15/28 (144A)	$ 432,250
2,570,000	Renewable Energy Group, Inc., 5.875%, 6/1/28 (144A)	2,722,015
	Total Energy-Alternate Sources	$ 3,154,265
	Engineering & Construction — 2.0%
5,175,000	Artera Services LLC, 9.033%, 12/4/25 (144A)	$ 4,890,375
2,850,000	Brundage-Bone Concrete Pumping Holdings, Inc.,
	6.00%, 2/1/26 (144A)	2,664,750
1,895,000	Promontoria Holding 264 BV, 7.875%, 3/1/27 (144A)	1,781,300
1,450,000	TopBuild Corp., 4.125%, 2/15/32 (144A)	1,249,257
	Total Engineering & Construction	$ 10,585,682
	Entertainment — 2.0%
2,175,000	CDI Escrow Issuer, Inc., 5.75%, 4/1/30 (144A)	$ 2,096,504
2,030,000	Lions Gate Capital Holdings LLC, 5.50%,
	4/15/29 (144A)	1,799,575
3,110,000	Mohegan Gaming & Entertainment, 8.00%,
	2/1/26 (144A)	2,742,242
1,115,000	Scientific Games Holdings LP/Scientific Games
	US FinCo, Inc., 6.625%, 3/1/30 (144A)	1,059,250
3,230,000	SeaWorld Parks & Entertainment, Inc., 5.25%,
	8/15/29 (144A)	2,939,042
	Total Entertainment	$ 10,636,613
	Environmental Control — 0.8%
875,000	GFL Environmental, Inc., 4.00%, 8/1/28 (144A)	$ 770,000
2,505,000	GFL Environmental, Inc., 4.375%, 8/15/29 (144A)	2,222,436
1,337,000	Tervita Corp., 11.00%, 12/1/25 (144A)	1,490,755
	Total Environmental Control	$ 4,483,191
	Food — 1.3%
3,595,000	FAGE International SA/FAGE USA Dairy Industry,
	Inc., 5.625%, 8/15/26 (144A)	$ 3,346,619
1,239,000	Simmons Foods Inc/Simmons Prepared Foods Inc/
	Simmons Pet Food, Inc./Simmons Feed, 4.625%,
	3/1/29 (144A)	1,118,198
885,000	US Foods, Inc., 4.625%, 6/1/30 (144A)	792,075
1,835,000	US Foods, Inc., 4.75%, 2/15/29 (144A)	1,695,081
	Total Food	$ 6,951,973

The accompanying notes are an integral part of these financial statements.

Pioneer High Yield Fund | Semiannual Report | 4/30/22 25

Table of Contents

Schedule of Investments | 4/30/22

(unaudited) (continued)

Principal
Amount
USD ($)		Value
	Forest Products & Paper — 2.5%
1,318,000	Clearwater Paper Corp., 4.75%, 8/15/28 (144A)	$ 1,158,179
1,535,000	Glatfelter Corp., 4.75%, 11/15/29 (144A)	1,228,000
4,605,000	Mercer International, Inc., 5.125%, 2/1/29	4,277,631
3,858,000	Schweitzer-Mauduit International, Inc., 6.875%,
	10/1/26 (144A)	3,465,911
3,180,000	Sylvamo Corp., 7.00%, 9/1/29 (144A)	3,068,700
	Total Forest Products & Paper	$ 13,198,421
	Healthcare-Products — 0.5%
2,330,000	Mozart Debt Merger Sub, Inc., 3.875%, 4/1/29 (144A)	$ 2,032,925
1,020,000	Mozart Debt Merger Sub, Inc., 5.25%, 10/1/29 (144A)	887,400
	Total Healthcare-Products	$ 2,920,325
	Healthcare-Services — 2.3%
1,060,000	LifePoint Health, Inc., 5.375%, 1/15/29 (144A)	$ 906,300
1,960,000	Prime Healthcare Services, Inc., 7.25%, 11/1/25 (144A)	1,964,900
3,478,000	Surgery Center Holdings, Inc., 10.00%, 4/15/27 (144A)	3,634,510
1,783,000	Tenet Healthcare Corp., 4.375%, 1/15/30 (144A)	1,618,073
2,480,000	US Acute Care Solutions LLC, 6.375%, 3/1/26 (144A)	2,408,700
2,287,000	US Renal Care, Inc., 10.625%, 7/15/27 (144A)	1,972,537
	Total Healthcare-Services	$ 12,505,020
	Home Builders — 1.2%
3,790,000	Beazer Homes USA, Inc., 6.75%, 3/15/25	$ 3,777,493
1,525,000	KB Home, 4.00%, 6/15/31	1,303,875
1,865,000	M/I Homes, Inc., 3.95%, 2/15/30	1,533,886
	Total Home Builders	$ 6,615,254
	Household Products/Wares — 0.2%
1,360,000	Spectrum Brands, Inc., 5.50%, 7/15/30 (144A)	$ 1,265,623
	Total Household Products/Wares	$ 1,265,623
	Housewares — 0.3%
2,105,000	Scotts Miracle-Gro Co., 4.00%, 4/1/31	$ 1,731,363
	Total Housewares	$ 1,731,363
	Internet — 1.1%
2,161,000	Netflix, Inc., 5.375%, 11/15/29 (144A)	$ 2,163,161
3,655,000	Twitter, Inc., 5.00%, 3/1/30 (144A)	3,732,669
	Total Internet	$ 5,895,830
	Iron & Steel — 2.9%
1,474,000	Carpenter Technology Corp., 6.375%, 7/15/28	$ 1,468,635
2,715,000	Carpenter Technology Corp., 7.625%, 3/15/30	2,764,473
4,993,000	Cleveland-Cliffs, Inc., 6.75%, 3/15/26 (144A)	5,229,918

The accompanying notes are an integral part of these financial statements.

26 Pioneer High Yield Fund | Semiannual Report | 4/30/22

Table of Contents

Principal
Amount
USD ($)			Value
		Iron & Steel — (continued)
	1,255,000	Commercial Metals Co., 4.375%, 3/15/32	$ 1,120,087
	1,185,000	Mineral Resources, Ltd., 8.00%, 11/1/27 (144A)	1,180,556
	1,255,000	Mineral Resources, Ltd., 8.50%, 5/1/30 (144A)	1,245,587
	2,985,000	TMS International Corp., 6.25%, 4/15/29 (144A)	2,596,950
		Total Iron & Steel	$ 15,606,206
		Leisure Time — 2.1%
	365,000	Carnival Corp., 7.625%, 3/1/26 (144A)	$ 357,700
EUR	475,000	Carnival Corp., 7.625%, 3/1/26 (144A)	500,600
	500,000	Carnival Corp., 10.50%, 2/1/26 (144A)	550,000
	2,130,000	NCL Corp., Ltd., 5.875%, 3/15/26 (144A)	1,967,715
	875,000	NCL Corp., Ltd., 7.75%, 2/15/29 (144A)	848,750
	585,000	NCL Finance, Ltd., 6.125%, 3/15/28 (144A)	526,500
	2,250,000	Royal Caribbean Cruises, Ltd., 9.125%, 6/15/23 (144A)	2,322,754
	709,000	Royal Caribbean Cruises, Ltd., 11.50%, 6/1/25 (144A)	770,825
	2,978,000	Viking Cruises, Ltd., 5.875%, 9/15/27 (144A)	2,522,813
	1,165,000	Viking Ocean Cruises Ship VII, Ltd., 5.625%,
		2/15/29 (144A)	1,028,112
		Total Leisure Time	$ 11,395,769
		Lodging — 0.6%
	1,810,000	Hilton Grand Vacations Borrower Escrow LLC/
		Hilton Grand
		Vacations Borrower Esc, 5.00%, 6/1/29 (144A)	$ 1,633,525
	1,270,000	Travel + Leisure Co., 6.625%, 7/31/26 (144A)	1,297,775
		Total Lodging	$ 2,931,300
		Media — 3.0%
	1,140,000	CCO Holdings LLC/CCO Holdings Capital Corp.,
		4.50%, 6/1/33 (144A)	$ 932,315
	2,290,000	CCO Holdings LLC/CCO Holdings Capital Corp.,
		5.00%, 2/1/28 (144A)	2,181,591
	2,869,000	CCO Holdings LLC/CCO Holdings Capital Corp.,
		5.125%, 5/1/27 (144A)	2,797,275
	200,000	CSC Holdings LLC, 5.00%, 11/15/31 (144A)	154,666
	2,000,000	CSC Holdings LLC, 5.375%, 2/1/28 (144A)	1,836,270
	2,672,000	CSC Holdings LLC, 7.50%, 4/1/28 (144A)	2,463,183
	3,331,000	McGraw-Hill Education, Inc., 8.00%, 8/1/29 (144A)	2,981,245
	665,000	News Corp., 5.125%, 2/15/32 (144A)	635,075
	2,165,000	VZ Secured Financing BV, 5.00%, 1/15/32 (144A)	1,867,313
		Total Media	$ 15,848,933
		Metal Fabricate/Hardware — 0.2%
	1,230,000	Park-Ohio Industries, Inc., 6.625%, 4/15/27	$ 931,725
		Total Metal Fabricate/Hardware	$ 931,725

The accompanying notes are an integral part of these financial statements.

Pioneer High Yield Fund | Semiannual Report | 4/30/22 27

Table of Contents

Schedule of Investments | 4/30/22

(unaudited) (continued)


Principal
Amount
USD ($)		Value
	Mining — 2.4%
1,856,000	Coeur Mining, Inc., 5.125%, 2/15/29 (144A)	$ 1,489,440
3,843,000	Eldorado Gold Corp., 6.25%, 9/1/29 (144A)	3,722,695
625,000	First Quantum Minerals, Ltd., 6.875%, 3/1/26 (144A)	628,125
1,680,000	First Quantum Minerals, Ltd., 6.875%, 10/15/27 (144A)	1,688,400
200,000	First Quantum Minerals, Ltd., 7.25%, 4/1/23 (144A)	199,954
2,065,000	FMG Resources August 2006 Pty, Ltd., 6.125%,
	4/15/32 (144A)	2,046,560
2,503,000	IAMGOLD Corp., 5.75%, 10/15/28 (144A)	2,129,402
900,000	Novelis Corp., 3.875%, 8/15/31 (144A)	771,750
	Total Mining	$ 12,676,326
	Oil & Gas — 11.2%
2,066,000	Aethon United BR LP/Aethon United Finance Corp.,
	8.25%, 2/15/26 (144A)	$ 2,129,073
1,770,000	Ascent Resources Utica Holdings LLC/ARU Finance
	Corp., 5.875%, 6/30/29 (144A)	1,713,201
5,445,000	Baytex Energy Corp., 8.75%, 4/1/27 (144A)	5,756,400
4,307,000	Energean Plc, 6.50%, 4/30/27 (144A)	4,046,426
2,740,000	Harbour Energy Plc, 5.50%, 10/15/26 (144A)	2,657,800
850,000	Hilcorp Energy I LP/Hilcorp Finance Co., 6.00%,
	4/15/30 (144A)	841,500
850,000	Hilcorp Energy I LP/Hilcorp Finance Co., 6.25%,
	4/15/32 (144A)	826,625
2,558,000	International Petroleum Corp., 7.25%, 2/1/27 (144A)	2,519,630
1,365,000	Kosmos Energy, Ltd., 7.75%, 5/1/27 (144A)	1,351,350
2,535,000	MEG Energy Corp., 5.875%, 2/1/29 (144A)	2,481,435
1,245,000	MEG Energy Corp., 7.125%, 2/1/27 (144A)	1,264,298
470,000	Nabors Industries, Inc., 7.375%, 5/15/27 (144A)	479,494
1,739,000	Nabors Industries, Ltd., 7.50%, 1/15/28 (144A)	1,665,093
3,259,000	Neptune Energy Bondco Plc, 6.625%, 5/15/25 (144A)	3,228,039
3,320,000	Occidental Petroleum Corp., 4.40%, 4/15/46	2,847,232
665,000	Occidental Petroleum Corp., 5.50%, 12/1/25	676,638
2,790,000	Parkland Corp., 4.625%, 5/1/30 (144A)	2,441,250
608,000	Precision Drilling Corp., 6.875%, 1/15/29 (144A)	589,900
1,755,000	Range Resources Corp., 4.75%, 2/15/30 (144A)	1,671,093
1,628,000	Shelf Drilling Holdings, Ltd., 8.25%, 2/15/25 (144A)	1,355,310
1,635,000	Shelf Drilling Holdings, Ltd., 8.875%, 11/15/24 (144A)	1,667,700
2,988,000	Southwestern Energy Co., 5.375%, 3/15/30	2,950,202
3,226,000	Strathcona Resources, Ltd., 6.875%, 8/1/26 (144A)	3,121,155
1,885,000	Sunoco LP/Sunoco Finance Corp., 4.50%,
	4/30/30 (144A)	1,689,431
3,335,000	Tap Rock Resources LLC, 7.00%, 10/1/26 (144A)	3,369,050
1,666,318	Transocean Sentry, Ltd., 5.375%, 5/15/23 (144A)	1,616,328

The accompanying notes are an integral part of these financial statements.

28 Pioneer High Yield Fund | Semiannual Report | 4/30/22

Table of Contents

Principal
Amount
USD ($)		Value
	Oil & Gas — (continued)
2,240,000	Tullow Oil Plc, 10.25%, 5/15/26 (144A)	$ 2,224,096
2,560,000	Vermilion Energy, Inc., 6.875%, 5/1/30 (144A)	2,499,200
	Total Oil & Gas	$ 59,678,949
	Oil & Gas Services — 0.3%
1,448,000	Exterran Energy Solutions LP/EES Finance Corp.,
	8.125%, 5/1/25	$ 1,451,620
	Total Oil & Gas Services	$ 1,451,620
	Packaging & Containers — 1.3%
1,805,000	Intertape Polymer Group, Inc., 4.375%, 6/15/29 (144A)	$ 1,857,128
3,835,000	OI European Group BV, 4.75%, 2/15/30 (144A)	3,374,800
1,810,000	Sealed Air Corp., 5.00%, 4/15/29 (144A)	1,796,425
	Total Packaging & Containers	$ 7,028,353
	Pharmaceuticals — 2.6%
1,420,000	AdaptHealth LLC, 5.125%, 3/1/30 (144A)	$ 1,221,200
2,087,000	Bausch Health Americas, Inc., 8.50%, 1/31/27 (144A)	1,971,860
3,300,000	Owens & Minor, Inc., 6.625%, 4/1/30 (144A)	3,242,052
1,700,000	P&L Development LLC/PLD Finance Corp., 7.75%,
	11/15/25 (144A)	1,498,125
1,746,000	Par Pharmaceutical, Inc., 7.50%, 4/1/27 (144A)	1,593,016
2,937,000	Teva Pharmaceutical Finance Netherlands III BV,
	2.80%, 7/21/23	2,848,332
778,000	Teva Pharmaceutical Finance Netherlands III BV,
	4.75%, 5/9/27	711,870
778,000	Teva Pharmaceutical Finance Netherlands III BV,
	5.125%, 5/9/29	706,035
	Total Pharmaceuticals	$ 13,792,490
	Pipelines — 4.7%
3,340,000	CQP Holdco LP/BIP-V Chinook Holdco LLC, 5.50%,
	6/15/31 (144A)	$ 3,080,482
3,400,000	DCP Midstream Operating LP, 5.60%, 4/1/44	3,250,332
2,606,000	Delek Logistics Partners LP/Delek Logistics Finance
	Corp., 6.75%, 5/15/25	2,579,940
1,215,000	Delek Logistics Partners LP/Delek Logistics Finance
	Corp., 7.125%, 6/1/28 (144A)	1,161,370
3,520,000(f)(g)	Energy Transfer LP, 7.125% (5 Year CMT
	Index + 531 bps)	3,321,472
68,000	EnLink Midstream LLC, 5.375%, 6/1/29	66,186
1,375,000	EnLink Midstream Partners LP, 4.15%, 6/1/25	1,337,188
685,000	EnLink Midstream Partners LP, 5.05%, 4/1/45	527,388
1,313,000	EnLink Midstream Partners LP, 5.60%, 4/1/44	1,083,323
1,295,000	Genesis Energy LP/Genesis Energy Finance Corp.,
	8.00%, 1/15/27	1,270,058

The accompanying notes are an integral part of these financial statements.

Pioneer High Yield Fund | Semiannual Report | 4/30/22 29

Table of Contents

Schedule of Investments | 4/30/22

(unaudited) (continued)

Principal
Amount
USD ($)		Value
	Pipelines— (continued)
2,195,000	Golar LNG, Ltd., 7.00%, 10/20/25 (144A)	$ 2,162,075
4,126,000	Harvest Midstream I LP, 7.50%, 9/1/28 (144A)	4,187,890
500,000	Venture Global Calcasieu Pass LLC, 3.875%,
	11/1/33 (144A)	435,025
875,000	Venture Global Calcasieu Pass LLC, 4.125%,
	8/15/31 (144A)	794,063
	Total Pipelines	$ 25,256,792
	Real Estate — 0.9%
2,470,000	Kennedy-Wilson, Inc., 4.75%, 2/1/30	$ 2,235,350
3,140,000	Realogy Group LLC/Realogy Co.-Issuer Corp.,
	5.25%, 4/15/30 (144A)	2,539,475
	Total Real Estate	$ 4,774,825
	REITs — 2.0%
2,725,000	HAT Holdings I LLC/HAT Holdings II LLC, 3.375%,
	6/15/26 (144A)	$ 2,502,994
3,190,000	iStar, Inc., 4.75%, 10/1/24	3,102,275
611,000	Starwood Property Trust, Inc., 3.75%, 12/31/24 (144A)	588,088
2,890,000	Uniti Group LP/Uniti Fiber Holdings, Inc./CSL
	Capital LLC, 6.00%, 1/15/30 (144A)	2,405,925
2,090,000	Uniti Group LP/Uniti Group Finance, Inc./CSL
	Capital LLC, 6.50%, 2/15/29 (144A)	1,802,625
	Total REITs	$ 10,401,907
	Retail — 3.5%
2,660,000	AAG FH LP/AAG FH Finco, Inc., 9.75%,
	7/15/24 (144A)	$ 3,006,864
905,000	Bath & Body Works, Inc., 6.625%, 10/1/30 (144A)	900,117
1,845,000	Beacon Roofing Supply, Inc., 4.125%, 5/15/29 (144A)	1,618,234
845,000	Gap, Inc., 3.625%, 10/1/29 (144A)	687,327
465,000	Gap, Inc., 3.875%, 10/1/31 (144A)	370,698
1,490,000	Group 1 Automotive, Inc., 4.00%, 8/15/28 (144A)	1,340,598
275,000	GYP Holdings III Corp., 4.625%, 5/1/29 (144A)	243,719
865,000	Ken Garff Automotive LLC, 4.875%, 9/15/28 (144A)	786,522
3,775,000	LCM Investments Holdings II LLC, 4.875%,
	5/1/29 (144A)	3,308,108
995,000	Macy’s Retail Holdings LLC, 5.875%, 4/1/29 (144A)	943,877
2,866,000	Party City Holdings, Inc., 8.75%, 2/15/26 (144A)	2,625,972
675,000	SRS Distribution, Inc., 4.625%, 7/1/28 (144A)	617,969
450,000	SRS Distribution, Inc., 6.125%, 7/1/29 (144A)	397,116
1,834,000	Staples, Inc., 7.50%, 4/15/26 (144A)	1,751,470
	Total Retail	$ 18,598,591

The accompanying notes are an integral part of these financial statements.

30 Pioneer High Yield Fund | Semiannual Report | 4/30/22

Table of Contents

Principal
Amount
USD ($)		Value
	Software — 0.8%
4,360,000	Minerva Merger Sub, Inc., 6.50%, 2/15/30 (144A)	$ 4,014,492
	Total Software	$ 4,014,492
	Telecommunications — 4.3%
4,507,000	Altice France Holding SA, 6.00%, 2/15/28 (144A)	$ 3,722,016
465,000	Altice France SA, 5.125%, 1/15/29 (144A)	394,592
2,180,000	Altice France SA, 5.125%, 7/15/29 (144A)	1,845,501
1,510,000	CommScope Technologies LLC, 5.00%,
	3/15/27 (144A)	1,185,350
2,210,000	CommScope, Inc., 4.75%, 9/1/29 (144A)	1,847,759
1,081,000	CommScope, Inc., 8.25%, 3/1/27 (144A)	929,660
40,000	Level 3 Financing, Inc., 3.75%, 7/15/29 (144A)	32,500
3,168,000	Level 3 Financing, Inc., 4.625%, 9/15/27 (144A)	2,847,240
2,492,000	LogMeIn, Inc., 5.50%, 9/1/27 (144A)	2,180,500
800,000	Lumen Technologies, Inc., 4.00%, 2/15/27 (144A)	711,432
3,270,000	Lumen Technologies, Inc., 4.50%, 1/15/29 (144A)	2,583,300
2,120,000	Plantronics, Inc., 4.75%, 3/1/29 (144A)	2,154,450
2,685,000	Windstream Escrow LLC/Windstream Escrow
	Finance Corp., 7.75%, 8/15/28 (144A)	2,557,462
	Total Telecommunications	$ 22,991,762
	Transportation — 2.1%
2,891,000	Carriage Purchaser, Inc., 7.875%, 10/15/29 (144A)	$ 2,532,357
2,009,000	Danaos Corp., 8.50%, 3/1/28 (144A)	2,073,429
2,600,000	Seaspan Corp., 6.50%, 4/29/26 (144A)	2,643,420
3,590,000	Western Global Airlines LLC, 10.375%, 8/15/25 (144A)	3,681,114
	Total Transportation	$ 10,930,320
	Trucking & Leasing — 0.2%
1,205,000	Fortress Transportation and Infrastructure Investors
	LLC, 9.75%, 8/1/27 (144A)	$ 1,229,413
	Total Trucking & Leasing	$ 1,229,413
	TOTAL CORPORATE BONDS
	(Cost $495,272,359)	$ 463,458,375

Shares
	CONVERTIBLE PREFERRED STOCK — 0.3%
	of Net Assets
	Banks — 0.3%
1,561(f)	Wells Fargo & Co., 7.50%	$ 1,891,136
	Total Banks	$ 1,891,136
	TOTAL CONVERTIBLE PREFERRED STOCK
	(Cost $1,767,832)	$ 1,891,136

The accompanying notes are an integral part of these financial statements.

Pioneer High Yield Fund | Semiannual Report | 4/30/22 31

Table of Contents

Schedule of Investments | 4/30/22

(unaudited) (continued)

Shares		Value
	RIGHTS/WARRANTS — 0.0%†
	of Net Assets
	Aerospace & Defense — 0.0%†
56,875(c)(h)^	Avation Plc, 1/1/59	$ —
	Total Aerospace & Defense	$ —
Health Care Providers & Services — 0.0%†
2,136(c)(i)^	Option Care Health, Inc., 6/30/25	$ 7,326
2,136(c)(j)^	Option Care Health, Inc., 6/30/25		5,981
	Total Health Care Providers & Services	$ 13,307
	Metals & Mining — 0.0%†
4,728,525(k)	ANR, Inc., 3/31/23	$ 18,914
	Total Metals & Mining	$ 18,914
	Oil, Gas & Consumable Fuels — 0.0%†
921(c)(l)	Alpha Metallurgical Resources, Inc., 7/26/23	$ 117,888
	Total Oil, Gas & Consumable Fuels	$ 117,888
	RIGHTS/WARRANTS
	(Cost $598,118)	$ 150,109

Principal
Amount
USD ($)
	INSURANCE-LINKED SECURITIES — 0.3%
	of Net Assets#
	Event Linked Bonds — 0.0%†
	Multiperil – U.S. — 0.0%†
750,000(a)+	Caelus Re V, 0.913%, (1 Month U.S. Treasury Bill +
	10 bps), 6/5/24 (144A)	$ 66
450,000(a)	Caelus Re V, 0.913%, (3 Month U.S. Treasury Bill +
	10 bps), 6/9/25 (144A)		45
		$ 111
	Total Event Linked Bonds	$ 111

Face
Amount
USD ($)
	Collateralized Reinsurance — 0.1%
	Multiperil – Worldwide — 0.0%†
1,000,000(c)(m)+	Cypress Re 2017, 1/31/23	$ 100
555,123(c)(m)+	Dartmouth Re 2018, 1/31/23		117,186
39,000(d)(m)+	Limestone Re, 3/1/23 (144A)		—
333,342(c)(m)+	Oyster Bay Re 2018, 1/31/23		41,039
442,599(c)(m)+	Walton Health Re 2018, 6/15/22		35,233
		$ 193,558

The accompanying notes are an integral part of these financial statements.

32 Pioneer High Yield Fund | Semiannual Report | 4/30/22

Table of Contents

Face
Amount
USD ($)		Value
	Windstorm – Florida — 0.1%
400,000(c)(m)+	Formby Re 2018, 2/28/23	$ 35,804
750,000(c)(m)+	Portrush Re 2017, 6/15/22	478,575
		$ 514,379
	Windstorm – U.S. Regional — 0.0%†
500,000(c)(m)+	Oakmont Re 2017, 4/30/23	$ 14,700
	Total Collateralized Reinsurance	$ 722,637
	Reinsurance Sidecars — 0.2%
	Multiperil – U.S. — 0.0%†
1,400,000(c)(n)+	Harambee Re 2018, 12/31/22	$ 1,120
973,488(c)(n)+	Harambee Re 2019, 12/31/22	681
		$ 1,801
	Multiperil – Worldwide — 0.2%
8,504(n)+	Alturas Re 2019-2, 3/10/23	$ 2,929
1,000,000(c)(m)+	Bantry Re 2016, 3/31/23	60,450
400,000(c)(m)+	Bantry Re 2019, 12/31/22	13,585
2,152,482(c)(m)+	Berwick Re 2018-1, 12/31/22	166,387
1,067,182(c)(m)+	Berwick Re 2019-1, 12/31/22	127,528
7,850(d)(m)+	Eden Re II, 3/22/23 (144A)	19,459
400,000(c)(m)+	Gleneagles Re 2018, 12/31/22	47,320
411,569(c)(n)+	Lorenz Re 2019, 6/30/22	47,742
900,000(c)(m)+	Merion Re 2018-2, 12/31/22	148,950
2,000,000(c)(m)+	Pangaea Re 2016-2, 11/30/22	3,567
500,000(c)(m)+	Pangaea Re 2018-1, 12/31/22	10,527
500,000(c)(m)+	Pangaea Re 2018-3, 7/1/22	10,372
409,624(c)(m)+	Pangaea Re 2019-1, 2/1/23	8,536
367,657(c)(m)+	Pangaea Re 2019-3, 7/1/23	13,225
600,000(c)(n)+	Thopas Re 2019, 12/31/22	—
450,000(m)+	Versutus Re 2018, 12/31/22	—
397,146(m)+	Versutus Re 2019-A, 12/31/22	—
52,853(m)+	Versutus Re 2019-B, 12/31/22	—
300,000(c)(n)+	Viribus Re 2018, 12/31/22	—
127,384(c)(n)+	Viribus Re 2019, 12/31/22	3,337
405,831(c)(m)+	Woburn Re 2018, 12/31/22	22,456
419,863(c)(m)+	Woburn Re 2019, 12/31/22	94,822
		$ 801,192
	Total Reinsurance Sidecars	$ 802,993
	TOTAL INSURANCE-LINKED SECURITIES
	(Cost $3,534,837)	$ 1,525,741

The accompanying notes are an integral part of these financial statements.

Pioneer High Yield Fund | Semiannual Report | 4/30/22 33

Table of Contents

Schedule of Investments | 4/30/22

(unaudited) (continued)

Principal
Amount
USD ($)		Value
	U.S. GOVERNMENT AND AGENCY
	OBLIGATIONS — 2.6% of Net Assets
14,000,000(d)	U.S. Treasury Bills, 5/10/22	$ 13,999,638
	TOTAL U.S. GOVERNMENT AND AGENCY OBLIGATIONS
	(Cost $13,999,291)	$ 13,999,638
	SHORT TERM INVESTMENTS — 2.3%
	of Net Assets
	Open-End Fund — 2.3%
12,133,825(o)	Dreyfus Government Cash Management, Institutional
	Shares, 0.24%	$ 12,133,825
		$ 12,133,825
	TOTAL SHORT TERM INVESTMENTS
	(Cost $12,133,825)	$ 12,133,825
	TOTAL INVESTMENTS IN UNAFFILIATED ISSUERS — 99.0%
	(Cost $563,722,200)	$ 528,326,299
	OTHER ASSETS AND LIABILITIES — 1.0%	$ 5,098,368
	NET ASSETS — 100.0%	$ 533,424,667

bps

Basis Points.

CMT

Constant Maturity Treasury Index.

LIBOR

London Interbank Offered Rate.

REIT

Real Estate Investment Trust.

SOFR

Secured Overnight Financing Rate.

(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 April 30, 2022, the value of these securities amounted to $401,311,589, or 75.2% of net assets.

(a)

Floating rate note. Coupon rate, reference index and spread shown at April 30, 2022.

(b)

This term loan will settle after April 30, 2022, at which time the interest rate will be determined.

(c)

Non-income producing security.

(d)

Security issued with a zero coupon. Income is recognized through accretion of discount.

(e)

Payment-in-kind (PIK) security which may pay interest in the form of additional principal amount.

(f)

Security is perpetual in nature and has no stated maturity date.

(g)

The interest rate is subject to change periodically. The interest rate and/or reference index and spread shown at April 30, 2022.

(h)

Avation Plc, 1/1/59 warrants are exercisable into 56,875 shares.

(i)

Option Care Health, Inc., 6/30/25 warrants are exercisable into 2,136 shares.

(j)

Option Care Health, Inc., 6/30/25 warrants are exercisable into 2,136 shares.

(k)

ANR, Inc., 3/31/23 warrants are exercisable into 4,728,525 shares.

(l)

Alpha Metallurgical Resources, Inc. 7/25/23 warrants are exercisable into 921 shares.

The accompanying notes are an integral part of these financial statements.

34 Pioneer High Yield Fund | Semiannual Report | 4/30/22

Table of Contents

(m)

Issued as participation notes.

(n)

Issued as preference shares.

(o)

Rate periodically changes. Rate disclosed is the 7-day yield at April 30, 2022.

Senior secured floating rate loan interests in which the Fund invests generally pay interest at rates that are periodically re-determined 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, (ii) the prime rate offered by one or more major United States banks, (iii) the rate of a certificate of deposit or (iv) other base lending rates used by commercial lenders. The interest rate shown is the rate accruing at April 30, 2022.

†

Amount rounds to less than 0.1%.

Security is valued using fair value methods (other than prices supplied by independent pricing services or broker dealers).

Security that used significant unobservable inputs to determine its value.

Securities are restricted as to resale.


Restricted Securities	Acquisition date	Cost	Value
Alturas Re 2019-2	12/19/2018	$ 8,504	$ 2,929
Bantry Re 2016	2/6/2019	60,450	60,450
Bantry Re 2019	2/1/2019	—	13,585
Berwick Re 2018-1	1/10/2018	314,406	166,387
Berwick Re 2019-1	12/31/2018	127,519	127,528
Caelus Re V	4/27/2017	750,000	66
Caelus Re V	5/4/2018	450,000	45
Cypress Re 2017	1/24/2017	3,361	100
Dartmouth Re 2018	1/18/2018	225,619	117,186
Eden Re II	1/22/2019	921	19,459
Formby Re 2018	7/9/2018	24,237	35,804
Gleneagles Re 2018	12/27/2017	32,109	47,320
Harambee Re 2018	12/19/2017	29,722	1,120
Harambee Re 2019	4/24/2019	—	681
Limestone Re	6/20/2018	287	—
Lorenz Re 2019	7/10/2019	129,176	47,742
Merion Re 2018-2	12/28/2017	37,037	148,950
Oakmont Re 2017	5/10/2017	—	14,700
Oyster Bay Re 2018	1/17/2018	36,022	41,039
Pangaea Re 2016-2	5/31/2016	—	3,567
Pangaea Re 2018-1	1/11/2018	71,503	10,527
Pangaea Re 2018-3	5/31/2018	120,430	10,372
Pangaea Re 2019-1	1/9/2019	4,301	8,536
Pangaea Re 2019-3	7/25/2019	11,030	13,225
Portrush Re 2017	6/12/2017	575,239	478,575
Thopas Re 2019	12/21/2018	—	—
Versutus Re 2018	1/31/2018	—	—
Versutus Re 2019-A	1/28/2019	—	—
Versutus Re 2019-B	12/24/2018	—	—
Viribus Re 2018	12/22/2017	23,670	—
Viribus Re 2019	3/25/2019	—	3,337
Walton Health Re 2018	6/25/2018	282,705	35,233
Woburn Re 2018	3/20/2018	136,283	22,456
Woburn Re 2019	1/30/2019	80,306	94,822
Total Restricted Securities			$1,525,741
% of Net assets			0.3%

The accompanying notes are an integral part of these financial statements.

Pioneer High Yield Fund | Semiannual Report | 4/30/22 35

Table of Contents

Schedule of Investments | 4/30/22

(unaudited) (continued)

SWAP CONTRACTS

CENTRALLY CLEARED CREDIT DEFAULT SWAP CONTRACTS — BUY PROTECTION
	Reference		Annual
Notional	Obligation/	Pay/	Fixed	Expiration	Premiums	Unrealized		Market
Amount ($)⁽¹⁾	Index	Receive⁽²⁾	Rate	Date	Paid	Appreciation	Value
31,000,000	Markit CDX	Pay	5.00%	6/22/27	$(1,733,129)	$1,064,569		$(668,560)
	North America
	High Yield
	Series 38

TOTAL CENTRALLY CLEARED CREDIT DEFAULT
SWAP CONTRACTS — BUY PROTECTION					$(1,733,129)	$1,064,569		$(668,560)

CENTRALLY CLEARED CREDIT DEFAULT SWAP CONTRACTS — SELL PROTECTION
	Reference		Annual
Notional	Obligation/	Pay/	Fixed	Expiration	Premiums	Unrealized		Market
Amount ($)⁽¹⁾Index		Receive⁽³⁾	Rate	Date	(Received)	Appreciation	Value
1,619,800	Markit CDX	Receive	5.00%	12/20/24	$ (3,260)		$71,864	$ 68,604
	North America
	High Yield
	Series 33

TOTAL CENTRALLY CLEARED CREDIT DEFAULT
SWAP CONTRACTS — SELL PROTECTION					$ (3,260) $		71,864	$ 68,604
TOTAL SWAP CONTRACTS					$(1,736,389)	$1,136,433		$(599,956)

⁽¹⁾

The notional amount is the maximum amount that a seller of credit protection would be obligated to pay upon occurrence of a credit event.

⁽²⁾

Pays quarterly.

⁽³⁾

Receives quarterly.

Principal amounts are denominated in U.S. dollars (“USD”) unless otherwise noted.

EUR — Euro

Purchases and sales of securities (excluding short term investments) for the six months ended April 30, 2022, aggregated $126,004,916 and $183,449,121, respectively.

The Fund is permitted to engage in purchase and sale transactions (“cross trades”) with certain funds and accounts for which the Amundi Asset Management US, Inc. (the “Adviser”) serves as the Fund’s investment adviser, as set forth in Rule 17a-7 under the Investment Company Act of 1940, pursuant to procedures adopted by the Board of Trustees. Under these procedures, cross trades are effected at current market prices. During the six months ended April 30, 2022, the Fund did not engage in any cross trade activity.

At April 30, 2022, the net unrealized depreciation on investments based on cost for federal tax purposes of $558,044,213 was as follows:


Aggregate gross unrealized appreciation for all investments in which
there is an excess of value over tax cost	$ 11,005,725
Aggregate gross unrealized depreciation for all investments in which
there is an excess of tax cost over value	(41,323,595)
Net unrealized depreciation	$(30,317,870)

The accompanying notes are an integral part of these financial statements.

36 Pioneer High Yield Fund | Semiannual Report | 4/30/22

Table of Contents

Various inputs are used in determining the value of the Fund’s investments. These inputs are summarized in the three broad levels below.

Level 1 – unadjusted 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 risks, etc.). See Notes to Financial Statements — Note 1A.

Level 3 – significant unobservable inputs (including the Fund’s own assumptions in determining fair value of investments). See Notes to Financial Statements — Note 1A.

The following is a summary of the inputs used as of April 30, 2022, in valuing the Fund’s investments:

	Level 1	Level 2	Level 3	Total
Senior Secured Floating
Rate Loan Interests	$ —	$ 13,909,367	$ —	$ 13,909,367
Common Stocks	2,295,535	—	—	2,295,535
Collateralized Mortgage
Obligations	—	131,378	—	131,378
Commercial Mortgage-
Backed Security	—	875,876	—	875,876
Convertible Corporate Bonds	—	17,955,319	—	17,955,319
Corporate Bonds	—	463,458,375	—	463,458,375
Convertible Preferred Stock	1,891,136	—	—	1,891,136
Rights/Warrants	150,109	—	—	150,109
Insurance-Linked Securities
Event Linked Bonds
Multiperil – U.S.	—	45	66	111
Collateralized Reinsurance
Multiperil – Worldwide	—	—	193,558	193,558
Windstorm – Florida	—	—	514,379	514,379
Windstorm – U.S. Regional	—	—	14,700	14,700
Reinsurance Sidecars
Multiperil – U.S.	—	—	1,801	1,801
Multiperil – Worldwide	—	—	801,192	801,192
U.S. Government and
Agency Obligations	—	13,999,638	—	13,999,638
Open-End Fund	12,133,825	—	—	12,133,825
Total Investments
in Securities	$16,470,605	$510,329,998	$1,525,696	$528,326,299
Other Financial Instruments
Swap contracts, at value	$ —	$ (599,956)	$ —	$ (599,956)
Total Other
Financial Instruments	$ —	$ (599,956)	$ —	$ (599,956)

The accompanying notes are an integral part of these financial statements.

Pioneer High Yield Fund | Semiannual Report | 4/30/22 37

Table of Contents

Schedule of Investments | 4/30/22

(unaudited) (continued)

The following is a reconciliation of assets valued using significant unobservable inputs (Level 3):

	Insurance-
	Linked
	Securities
Balance as of 10/31/21	$2,159,016
Realized gain (loss)⁽¹⁾	(538,708)
Changed in unrealized appreciation (depreciation)⁽²⁾	305,625
Accrued discounts/premiums	(66,121)
Purchases	—
Sales	(334,182)
Transfers in to Level 3*	66
Transfers out of Level 3*	—
Balance as of 4/30/22	$1,525,696

⁽¹⁾

Realized gain (loss) on these securities is included in the realized gain (loss) from investments on the Statement of Operations.

⁽²⁾

Unrealized appreciation (depreciation) on these securities is included in the change in unrealized appreciation (depreciation) from investments on the Statement of Operations.

Transfers are calculated on the beginning of period value. During the six months ended April 30, 2022, securities with an aggregate market value of $66 transferred from Level 2 to Level 3, as there were significant observable inputs to determine their value. There were no other transfers in or out of Level 3.

Net change in unrealized appreciation (depreciation) of Level 3 investments still
held and considered Level 3 at April 30, 2022:	$(10,236)

The accompanying notes are an integral part of these financial statements.

38 Pioneer High Yield Fund | Semiannual Report | 4/30/22

Table of Contents

Statement of Assets and Liabilities | 4/30/22

(unaudited)

ASSETS:
Investments in unaffiliated issuers, at value (cost $563,722,200)	$528,326,299
Foreign currencies, at value (cost $81,285)	73,644
Swaps collateral	2,393,681
Variation margin for centrally cleared swap contracts	194,496
Receivables —
Investment securities sold	171,535
Fund shares sold	625,028
Dividends	24,047
Interest	7,242,230
Due from the Adviser	6,017
Other assets	53,934
Total assets	$539,110,911
LIABILITIES:
Overdraft due to custodian	$ 1,845
Payables —
Investment securities purchased	3,343,175
Fund shares repurchased	1,074,038
Distributions	255,297
Trustees’ fees	1,968
Transfer agent fees	234,191
Swap contracts, at value (net premiums received $1,736,389)	599,956
Due to affiliates	70,301
Accrued expenses	105,473
Total liabilities	$ 5,686,244
NET ASSETS:
Paid-in capital	$600,304,826
Distributable earnings (loss)	(66,880,159)
Net assets	$533,424,667
NET ASSET VALUE PER SHARE:
No par value (unlimited number of shares authorized)
Class A (based on $360,267,909/40,543,769 shares)	$ 8.89
Class C (based on $9,932,989/1,093,363 shares)	$ 9.08
Class R (based on $9,358,190/929,014 shares)	$ 10.07
Class Y (based on $153,865,579/17,286,673 shares)	$ 8.90
MAXIMUM OFFERING PRICE PER SHARE:
Class A (based on $8.89 net asset value per share/100%-4.50%
maximum sales charge)	$ 9.31

The accompanying notes are an integral part of these financial statements.

Pioneer High Yield Fund | Semiannual Report | 4/30/22 39

Table of Contents

Statement of Operations (unaudited)

FOR THE SIX MONTHS ENDED 4/30/22

INVESTMENT INCOME:
Interest from unaffiliated issuers	$ 16,323,791
Dividends from unaffiliated issuers	209,423
Total Investment Income		$ 16,533,214
EXPENSES:
Management fees	$ 2,023,582
Administrative expenses	90,288
Transfer agent fees
Class A	253,991
Class C	5,995
Class R	13,463
Class Y	90,570
Distribution fees
Class A	491,927
Class C	53,311
Class R	25,899
Shareowner communications expense	48,490
Custodian fees	7,654
Registration fees	42,870
Professional fees	65,279
Printing expense	14,613
Pricing fees	1,415
Trustees' fees	12,568
Insurance expense	587
Miscellaneous	53,362
Total expenses		$ 3,295,864
Less fees waived and expenses reimbursed
by the Adviser		(223,887)
Net expenses		$ 3,071,977
Net investment income		$ 13,461,237
REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS:
Net realized gain (loss) on:
Investments in unaffiliated issuers	$ 1,030,393
Swap contracts	(4,427,748)
Other assets and liabilities denominated in
foreign currencies	(588)	$ (3,397,943)
Change in net unrealized appreciation (depreciation) on:
Investments in unaffiliated issuers	$(50,145,927)
Swap contracts	5,682,436
Other assets and liabilities denominated in
foreign currencies	(6,415)	$(44,469,906)
Net realized and unrealized gain (loss) on investments		$(47,867,849)
Net decrease in net assets resulting from operations		$(34,406,612)

The accompanying notes are an integral part of these financial statements.

40 Pioneer High Yield Fund | Semiannual Report | 4/30/22

Table of Contents

Statements of Changes in Net Assets

	Six Months
	Ended
	4/30/22	Year Ended
	(unaudited)	10/31/21
FROM OPERATIONS:
Net investment income (loss)	$ 13,461,237	$ 30,600,066
Net realized gain (loss) on investments	(3,397,943)	24,703,034
Change in net unrealized appreciation (depreciation)
on investments	(44,469,906)	18,785,475
Net increase (decrease) in net assets resulting
from operations	$ (34,406,612)	$ 74,088,575
DISTRIBUTIONS TO SHAREOWNERS:
Class A ($0.19 and $0.36 per share, respectively)	$ (7,806,929)	$ (16,463,323)
Class C ($0.15 and $0.28 per share, respectively)	(165,286)	(379,215)
Class R ($0.18 and $0.37 per share, respectively)	(180,301)	(402,724)
Class Y ($0.20 and $0.38 per share, respectively)	(3,579,869)	(7,507,889)
TAX RETURN OF CAPITAL
Class A ($— and $0.07 per share, respectively)	—	(3,220,770)
Class C ($— and $0.07 per share, respectively)	—	(86,724)
Class R ($— and $0.07 per share, respectively)	—	(76,334)
Class Y ($— and $0.07 per share, respectively)	—	(1,384,516)
Total distributions to shareowners	$ (11,732,385)	$ (29,521,495)
FROM FUND SHARE TRANSACTIONS:
Net proceeds from sales of shares	$ 98,757,940	$ 109,704,259
Reinvestment of distributions	10,595,526	26,527,715
Cost of shares repurchased	(170,638,772)	(162,023,471)
Net decrease in net assets resulting from Fund
share transactions	$ (61,285,306)	$ (25,791,497)
Net increase (decrease) in net assets	$(107,424,303)	$ 18,775,583
NET ASSETS:
Beginning of period	$ 640,848,970	$ 622,073,387
End of period	$ 533,424,667	$ 640,848,970

The accompanying notes are an integral part of these financial statements.

Pioneer High Yield Fund | Semiannual Report | 4/30/22 41

Table of Contents

Statements of Changes in Net Assets

(continued)

	Six Months	Six Months
	Ended	Ended	Year	Year
	4/30/22	4/30/22	Ended	Ended
	Shares	Amount	10/31/21	10/31/21
	(unaudited)	(unaudited)	Shares	Amount
Class A
Shares sold	6,090,043	$ 56,511,894	6,282,421	$ 60,032,320
Reinvestment of
distributions	758,059	7,068,716	1,836,108	17,608,525
Less shares repurchased	(10,510,467)	(98,299,751)	(10,308,918)	(98,827,284)
Net decrease	(3,662,365)	$(34,719,141)	(2,190,389)	$(21,186,439)
Class C
Shares sold	120,511	$ 1,166,563	239,766	$ 2,354,623
Reinvestment of
distributions	17,062	162,472	46,478	454,790
Less shares repurchased	(219,940)	(2,125,600)	(963,408)	(9,362,190)
Net decrease	(82,367)	$ (796,565)	(677,164)	$ (6,552,777)
Class R
Shares sold	320,254	$ 3,349,051	295,440	$ 3,207,275
Reinvestment of
distributions	17,040	180,082	43,996	478,525
Less shares repurchased	(445,710)	(4,686,200)	(434,787)	(4,737,769)
Net decrease	(108,416)	$ (1,157,067)	(95,351)	$ (1,051,969)
Class Y
Shares sold	3,940,916	$ 37,730,432	4,599,602	$ 44,110,041
Reinvestment of
distributions	340,971	3,184,256	831,672	7,985,875
Less shares repurchased	(6,901,545)	(65,527,221)	(5,119,185)	(49,096,228)
Net increase
(decrease)	(2,619,658)	$(24,612,533)	312,089	$ 2,999,688

The accompanying notes are an integral part of these financial statements.

42 Pioneer High Yield Fund | Semiannual Report | 4/30/22

Table of Contents

Financial Highlights


	Six Months
	Ended	Year	Year	Year	Year	Year
	4/30/22	Ended	Ended	Ended	Ended	Ended
	(unaudited)	10/31/21	10/31/20	10/31/19	10/31/18	10/31/17
Class A
Net asset value, beginning of period	$ 9.64	$ 8.99	$ 9.58	$ 9.37	$ 9.80	$ 9.43
Increase (decrease) from investment operations:
Net investment income (loss) (a)	$ 0.21	$ 0.45	$ 0.48	$ 0.47	$ 0.47	$ 0.46
Net realized and unrealized gain (loss) on investments	(0.77)	0.63	(0.58)	0.24	(0.45)	0.38
Net increase (decrease) from investment operations	$ (0.56)	$ 1.08	$ (0.10)	$ 0.71	$ 0.02	$ 0.84
Distributions to shareowners:
Net investment income	$ (0.19)	$ (0.36)	$ (0.49)	$ (0.50)	$ (0.45)	$ (0.47)
Tax return of capital	—	(0.07)	—	—	—	—
Total distributions	$ (0.19)	$ (0.43)	$ (0.49)	$ (0.50)	$ (0.45)	$ (0.47)
Net increase (decrease) in net asset value	$ (0.75)	$ 0.65	$ (0.59)	$ 0.21	$ (0.43)	$ 0.37
Net asset value, end of period	$ 8.89	$ 9.64	$ 8.99	$ 9.58	$ 9.37	$ 9.80
Total return (b)	(5.93)%(c)	12.13%	(0.89)%	7.82%	0.21%	9.05%(d)
Ratio of net expenses to average net assets	1.10%(e)	1.10%	1.10%	1.19%	1.14%	1.15%
Ratio of net investment income (loss) to average net assets	4.56%(e)	4.66%	5.24%	4.97%	4.87%	4.80%
Portfolio turnover rate	23%(c)	80%	85%	59%	45%	39%
Net assets, end of period (in thousands)	$360,268	$425,933	$417,137	$512,624	$537,907	$525,164
Ratios with no waiver of fees and assumption of expenses
by the Adviser and no reduction for fees paid indirectly:
Total expenses to average net assets	1.19%	1.20%	1.17%	1.19%	1.14%	1.15%
Net investment income (loss) to average net assets	4.47%	4.56%	5.17%	4.97%	4.87%	4.80%

(a)

The per-share data presented above is based on the average shares outstanding for the period presented.

(b)

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.

(c)

Not annualized.

(d)

If the Fund had not recognized gains in the settlement of class action lawsuits during the year ended October 31, 2017, the total return would have been 8.94%.

(e)

Annualized.

The accompanying notes are an integral part of these financial statements.

Pioneer High Yield Fund | Semiannual Report | 4/30/22 43

Table of Contents

Financial Highlights (continued)


	Six Months
	Ended	Year	Year	Year	Year	Year
	4/30/22	Ended	Ended	Ended	Ended	Ended
	(unaudited)	10/31/21	10/31/20	10/31/19	10/31/18	10/31/17
Class C
Net asset value, beginning of period	$ 9.84	$ 9.18	$ 9.79	$ 9.57	$ 10.01	$ 9.63
Increase (decrease) from investment operations:
Net investment income (loss) (a)	$ 0.18	$ 0.37	$ 0.41	$ 0.40	$ 0.40	$ 0.41
Net realized and unrealized gain (loss) on investments	(0.79)	0.64	(0.58)	0.25	(0.45)	0.38
Net increase (decrease) from investment operations	$ (0.61)	$ 1.01	$ (0.17)	$ 0.65	$ (0.05)	$ 0.79
Distributions to shareowners:
Net investment income	$ (0.15)	$ (0.28)	$ (0.44)	$ (0.43)	$ (0.39)	$ (0.41)
Tax return of capital	—	(0.07)	—	—	—	—
Total distributions	$ (0.15)	$ (0.35)	$ (0.44)	$ (0.43)	$ (0.39)	$ (0.41)
Net increase (decrease) in net asset value	$ (0.76)	$ 0.66	$ (0.61)	$ 0.22	$ (0.44)	$ 0.38
Net asset value, end of period	$ 9.08	$ 9.84	$ 9.18	$ 9.79	$ 9.57	$ 10.01
Total return (b)	(6.38)%(c)	11.13%	(1.71)%	6.98%	(0.52)%	8.29%(d)
Ratio of net expenses to average net assets	1.95%(e)	1.98%	1.87%	1.94%	1.86%	1.86%
Ratio of net investment income (loss) to average net assets	3.71%(e)	3.79%	4.48%	4.21%	4.10%	4.11%
Portfolio turnover rate	23%(c)	80%	85%	59%	45%	39%
Net assets, end of period (in thousands)	$9,933	$11,574	$17,019	$24,166	$37,546	$192,558

(a)

The per-share data presented above is based on the average shares outstanding for the period presented.

(b)

(c)

Not annualized.

(d)

If the Fund had not recognized gains in the settlement of class action lawsuits during the year ended October 31, 2017, the total return would have been 8.18%.

(e)

Annualized.

The accompanying notes are an integral part of these financial statements.

44 Pioneer High Yield Fund | Semiannual Report | 4/30/22

Table of Contents

	Six Months
	Ended	Year	Year	Year	Year	Year
	4/30/22	Ended	Ended	Ended	Ended	Ended
	(unaudited)	10/31/21	10/31/20	10/31/19	10/31/18	10/31/17
Class R
Net asset value, beginning of period	$10.93	$ 10.20	$ 10.84	$ 10.61	$ 11.09	$ 10.68
Increase (decrease) from investment operations:
Net investment income (loss) (a)	$ 0.22	$ 0.45	$ 0.50	$ 0.48	$ 0.49	$ 0.48
Net realized and unrealized gain (loss) on investments	(0.90)	0.72	(0.63)	0.27	(0.50)	0.41
Net increase (decrease) from investment operations	$ (0.68)	$ 1.17	$ (0.13)	$ 0.75	$ (0.01)	$ 0.89
Distributions to shareowners:
Net investment income	$ (0.18)	$ (0.37)	$ (0.51)	$ (0.52)	$ (0.47)	$ (0.48)
Tax return of capital	—	(0.07)	—	—	—	—
Total distributions	$ (0.18)	$ (0.44)	$ (0.51)	$ (0.52)	$ (0.47)	$ (0.48)
Net increase (decrease) in net asset value	$ (0.86)	$ 0.73	$ (0.64)	$ 0.23	$ (0.48)	$ 0.41
Net asset value, end of period	$10.07	$ 10.93	$ 10.20	$ 10.84	$ 10.61	$ 11.09
Total return (b)	(6.25)%(c)	11.55%	(1.08)%	7.28%	(0.14)%	8.50%(d)
Ratio of net expenses to average net assets	1.57%(e)	1.59%	1.51%	1.63%	1.50%	1.56%
Ratio of net investment income (loss) to average net assets	4.09%(e)	4.17%	4.82%	4.51%	4.48%	4.39%
Portfolio turnover rate	23%(c)	80%	85%	59%	45%	39%
Net assets, end of period (in thousands)	$9,358	$11,336	$11,556	$15,332	$18,405	$24,366

(a)

The per-share data presented above is based on the average shares outstanding for the period presented.

(b)

(c)

Not annualized.

(d)

If the Fund had not recognized gains in the settlement of class action lawsuits during the year ended October 31, 2017, the total return would have been 8.41%.

(e)

Annualized.

The accompanying notes are an integral part of these financial statements.

Pioneer High Yield Fund | Semiannual Report | 4/30/22 45

Table of Contents

Financial Highlights (continued)

	Six Months
	Ended	Year	Year	Year	Year	Year
	4/30/22	Ended	Ended	Ended	Ended	Ended
	(unaudited)	10/31/21	10/31/20	10/31/19	10/31/18	10/31/17
Class Y
Net asset value, beginning of period	$ 9.65	$ 9.00	$ 9.59	$ 9.38	$ 9.81	$ 9.44
Increase (decrease) from investment operations:
Net investment income (loss) (a)	$ 0.22	$ 0.47	$ 0.50	$ 0.50	$ 0.50	$ 0.49
Net realized and unrealized gain (loss) on investments	(0.77)	0.63	(0.57)	0.24	(0.45)	0.37
Net increase (decrease) from investment operations	$ (0.55)	$ 1.10	$ (0.07)	$ 0.74	$ 0.05	$ 0.86
Distributions to shareowners:
Net investment income	$ (0.20)	$ (0.38)	$ (0.52)	$ (0.53)	$ (0.48)	$ (0.49)
Tax return of capital	—	(0.07)	—	—	—	—
Total distributions	$ (0.20)	$ (0.45)	$ (0.52)	$ (0.53)	$ (0.48)	$ (0.49)
Net increase (decrease) in net asset value	$ (0.75)	$ 0.65	$ (0.59)	$ 0.21	$ (0.43)	$ 0.37
Net asset value, end of period	$ 8.90	$ 9.65	$ 9.00	$ 9.59	$ 9.38	$ 9.81
Total return (b)	(5.81)%(c)	12.40%	(0.62)%	8.12%	0.51%	9.34%(d)
Ratio of net expenses to average net assets	0.85%(e)	0.85%	0.85%	0.88%	0.85%	0.87%
Ratio of net investment income (loss) to average net assets	4.80%(e)	4.90%	5.50%	5.27%	5.15%	5.08%
Portfolio turnover rate	23%(c)	80%	85%	59%	45%	39%
Net assets, end of period (in thousands)	$153,866	$192,006	$176,362	$200,617	$205,543	$229,866
Ratios with no waiver of fees and assumption of expenses
by the Adviser and no reduction for fees paid indirectly:
Total expenses to average net assets	0.90%	0.90%	0.87%	0.88%	0.85%	0.87%
Net investment income (loss) to average net assets	4.75%	4.85%	5.48%	5.27%	5.15%	5.08%

(a)	The per-share data presented above is based on the average shares outstanding for the period presented.
(b)	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.
(c)	Not annualized.
(d)	If the Fund had not recognized gains in the settlement of class action lawsuits during the year ended October 31, 2017, the total return would have been 9.23%.
(e)	Annualized.

The accompanying notes are an integral part of these financial statements.

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Notes to Financial Statements | 4/30/22

1. Organization and Significant Accounting Policies

Pioneer High Yield Fund (the “Fund”) is a Delaware statutory trust. The Fund is registered under the Investment Company Act of 1940 as a diversified, open-end management investment company. The investment objective of the Fund is to maximize total return through a combination of income and capital appreciation.

The Fund offers five classes of shares designated as Class A, Class C, Class K, Class R and Class Y shares. Class K shares had not commenced operations as of April 30, 2022. Each class of shares represents an interest in the same portfolio of investments of the Fund and has identical rights (based on relative net asset values) to assets and liquidation proceeds. Share classes can bear different rates of class-specific fees and expenses, such as transfer agent and distribution fees. Differences in class-specific fees and expenses will result in differences in net investment income and, therefore, the payment of different dividends from net investment income earned by each class. The Amended and Restated Declaration of Trust of the Fund gives the Board of Trustees the flexibility to specify either per-share voting or dollar-weighted voting when submitting matters for shareowner approval. Under per-share voting, each share of a class of the Fund is entitled to one vote. Under dollar-weighted voting, a shareowner’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.

Amundi Asset Management US, Inc., an indirect, wholly owned subsidiary of Amundi and Amundi’s wholly owned subsidiary, Amundi USA, Inc., serves as the Fund’s investment adviser (the “Adviser”). Amundi Distributor US, Inc., an affiliate of the Adviser, serves as the Fund’s distributor (the “Distributor”).

In August 2018, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update 2018-13 “Disclosure Framework — Changes to the Disclosure Requirements for Fair Value Measurement” (“ASU 2018-13”) which modifies disclosure requirements for fair value measurements, principally for Level 3 securities and transfers between levels of the fair value hierarchy. ASU 2018-13 is effective for fiscal years beginning after December 15, 2019 and for interim periods within those fiscal years. The Fund has adopted ASU 2018-13 for the six months ended April 30, 2022.

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The impact to the Fund’s adoption was limited to changes in the Fund’s disclosures regarding fair value, primarily those disclosures related to transfers between levels of the fair value hierarchy and disclosure of the range and weighted average used to develop significant unobservable inputs for Level 3 fair value investments, when applicable.

In March 2020, FASB issued an Accounting Standard Update, ASU 2020-04, Reference Rate Reform (Topic 848) — Facilitation of the Effects of Reference Rate Reform on Financial Reporting (“ASU 2020-04”), which provides optional, temporary relief with respect to the financial reporting of contracts subject to certain types of modifications due to the planned discontinuation of the London Interbank Offered Rate (“LIBOR”) and other LIBOR-based reference rates at the end of 2021. The temporary relief provided by ASU 2020-04 is effective for certain reference rate-related contract modifications that occur during the period from March 12, 2020 through December 31, 2023. Management is evaluating the impact of ASU 2020-04 on the Fund’s investments, derivatives, debt and other contracts, if applicable, that will undergo reference rate-related modifications as a result of the reference rate reform.

The Fund is an investment company and follows investment company accounting and reporting guidance under U.S. Generally Accepted Accounting Principles (“U.S. GAAP”). U.S. GAAP requires the management of the Fund to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of income, expenses and gain or loss 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:

A. Security Valuation

The net asset value of the Fund is computed once daily, on each day the New York Stock Exchange (“NYSE”) is open, as of the close of regular trading on the NYSE.

Fixed-income securities are valued by using prices supplied by independent pricing services, which consider such factors as market prices, market events, quotations from one or more brokers, Treasury spreads, yields, maturities and ratings, or may use a pricing matrix or other fair value methods or techniques to provide an estimated value of the security or instrument. A pricing matrix is a means of valuing a debt security on the basis of current market prices for other debt securities, historical trading patterns in the market for fixed-income securities and/or other factors.

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Non-U.S. debt securities that are listed on an exchange will be valued at the bid price obtained from an independent third party pricing service. When independent third party pricing services are unable to supply prices, or when prices or market quotations are considered to be unreliable, the value of that security may be determined using quotations from one or more broker-dealers.

Loan interests are valued in accordance with guidelines established by the Board of Trustees at the mean between the last available bid and asked prices from one or more brokers or dealers as obtained from Loan Pricing Corporation, an independent third party pricing service. If price information is not available from Loan Pricing Corporation, or if the price information is deemed to be unreliable, price information will be obtained from an alternative loan interest pricing service. If no reliable price quotes are available from either the primary or alternative pricing service, broker quotes will be solicited.

Event-linked bonds are valued at the bid price obtained from an independent third party pricing service. Other insurance-linked securities (including reinsurance sidecars, collateralized reinsurance and industry loss warranties) may be valued at the bid price obtained from an independent pricing service, or through a third party using a pricing matrix, insurance industry valuation models, or other fair value methods or techniques to provide an estimated value of the instrument.

Equity securities that have traded on an exchange are valued by using the last sale price on the principal exchange where they are traded. Equity securities that have not traded on the date of valuation, or securities for which sale prices are not available, generally are valued using the mean between the last bid and asked prices or, if both last bid and asked prices are not available, at the last quoted bid price. Last sale and bid and asked prices are provided by independent third party pricing services. In the case of equity securities not traded on an exchange, prices are typically determined by independent third party pricing services using a variety of techniques and methods.

The value of foreign securities is translated into U.S. dollars based on foreign currency exchange rate quotations supplied by a third party pricing source. Trading in non-U.S. equity securities is substantially completed each day at various times prior to the close of the NYSE. The values of such securities used in computing the net asset value of the Fund’s shares are determined as of such times. The Fund may use a fair value model developed by an independent pricing service to value non-U.S. equity securities.

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Shares of open-end registered investment companies (including money market mutual funds) are valued at such funds’ net asset value. Shares of exchange-listed closed-end funds are valued by using the last sale price on he principal exchange where they are traded.

Forward foreign currency exchange contracts are valued daily using the foreign exchange rate or, for longer term forward contract positions, the spot currency rate and the forward points on a daily basis, in each case provided by a third party pricing service. Contracts whose forward settlement date falls between two quoted days are valued by interpolation.

Swap contracts, including interest rate swaps, caps and floors (other than centrally cleared swap contracts), are valued at the dealer quotations obtained from reputable International Swap Dealers Association members. Centrally cleared swaps are valued at the daily settlement price provided by the central clearing counterparty.

Securities or loan interests for which independent pricing services or broker-dealers are unable to supply prices or for which market prices and/or quotations are not readily available or are considered to be unreliable are valued by a fair valuation team comprised of certain personnel of the Adviser pursuant to procedures adopted by the Portfolio’s Board of Trustees. The Adviser’s fair valuation team uses fair value methods approved by the Valuation Committee of the Board of Trustees. The Adviser’s fair valuation team is responsible for monitoring developments that may impact fair valued securities and for discussing and assessing fair values on an ongoing basis, and at least quarterly, with the Valuation Committee of the Board of Trustees.

Inputs used when applying fair value methods to value a security may include credit ratings, the financial condition of the company, current market conditions and comparable securities. The Fund may use fair value methods if it is determined that a significant event has occurred after the close of the exchange or market on which the security trades and prior to the determination of the Fund’s net asset value. Examples of a significant event might include political or economic news, corporate restructurings, natural disasters, terrorist activity or trading halts. Thus, the valuation of the Fund’s securities may differ significantly from exchange prices, and such differences could be material.

At April 30, 2022, three securities were valued using fair value methods (in addition to securities valued using prices supplied by independent pricing services, broker-dealers or using a third party insurance pricing model) representing 0.00% of net assets. The value of these fair valued securities was $13,307.

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B. Investment Income and Transactions

Dividend income is recorded on the ex-dividend date, except that certain dividends from foreign securities where the ex-dividend date may have passed are recorded as soon as the Fund becomes aware of the ex-dividend data in the exercise of reasonable diligence.

Interest income, including interest on income-bearing cash accounts, is recorded on the accrual basis. Dividend and interest income are reported net of unrecoverable foreign taxes withheld at the applicable country rates and net of income accrued on defaulted securities.

Interest and dividend income payable by delivery of additional shares is reclassified as PIK (payment-in-kind) income upon receipt and is included in interest and dividend income, respectively.

Principal amounts of mortgage-backed securities are adjusted for monthly paydowns. Premiums and discounts related to certain mortgage-backed securities are amortized or accreted in proportion to the monthly paydowns. All discounts/premiums on purchase prices of debt securities are accreted/ amortized for financial reporting purposes over the life of the respective securities, and such accretion/amortization is included in interest income.

Security transactions are recorded as of trade date. Gains and losses on sales of investments are calculated on the identified cost method for both financial reporting and federal income tax purposes.

C. Foreign Currency Translation

The books and records of the Fund are maintained in U.S. dollars. Amounts denominated in foreign currencies are translated into U.S. dollars using current exchange rates.

Net realized gains and losses on foreign currency transactions, if any, represent, among other things, the net realized gains and losses on foreign currency exchange 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 on the Statement of Operations from the effects of changes in the market prices of those securities, but are included with the net realized and unrealized gain or loss on investments.

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D. Federal Income Taxes

It is the Fund’s policy to comply with the requirements of the Internal Revenue Code applicable to regulated investment companies and to distribute all of its net taxable income and net realized capital gains, if any, to its shareowners. Therefore, no provision for federal income taxes is required. As of October 31, 2021, the Fund did not accrue any interest or penalties with respect to uncertain tax positions, which, if applicable, would be recorded as an income tax expense on the Statement of Operations. Tax returns filed within the prior three years remain subject to examination by federal and state tax authorities.

The amount and character of income and capital gain distributions to shareowners are determined in accordance with federal income tax rules, which may differ from U.S. GAAP. Distributions in excess of net investment income or net realized gains are temporary over distributions 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.

A portion of the dividend income recorded by the Fund is from distributions by publicly traded real estate investment trusts (“REITs”), and such distributions for tax purposes may also consist of capital gains and return of capital. The actual return of capital and capital gains portions of such distributions will be determined by formal notifications from the REITs subsequent to the calendar year end. Distributions received from the REITs that are determined to be a return of capital are recorded by the Fund as a reduction of the cost basis of the securities held and those determined to be capital gain are reflected as such on the Statement of Operations.

The tax character of current year distributions payable will be determined at the end of the current taxable year. The tax character of distributions paid during the year ended October 31, 2021 was as follows:

	2021
Distributions paid from:
Ordinary income	$24,753,151
Tax return of capital	4,768,344
Total	$29,521,495

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The following shows the components of distributable earnings (losses) on a federal income tax basis at October 31, 2021:

	2021
Distributable earnings/(losses):
Capital loss carryforward	$(34,784,644)
Current year dividend payable	(225,068)
Net unrealized appreciation	14,268,550
Total	$(20,741,162)

The difference between book basis and tax basis unrealized appreciation is attributable to the tax deferral of losses on wash sales, the mark-to-market of foreign currency exchange contracts and swaps, adjustments relating to event linked bonds and swaps.

E. Fund Shares

The Fund records sales and repurchases of its shares as of trade date. The Distributor earned $5,536 in underwriting commissions on the sale of Class A shares during the six months ended April 30, 2022.

F. Class Allocations

Income, common expenses and realized and unrealized gains and losses are calculated at the Fund level and allocated daily to each class of shares based on its respective percentage of adjusted net assets at the beginning of the day.

Distribution fees are calculated based on the average daily net asset value attributable to Class A, Class C and Class R shares of the Fund, respectively (see Note 5). Class Y shares do not pay distribution fees. All expenses and fees paid to the Fund’s transfer agent for its services are allocated among the classes of shares based on the number of accounts in each class and the ratable allocation of related out-of-pocket expenses (see Note 4).

The Fund declares as daily dividends substantially all of its net investment income. All dividends are paid on a monthly basis. Short-term capital gain distributions, if any, may be declared with the daily dividends. Distributions to shareowners are recorded as of the ex-dividend date. Distributions paid by the Fund with respect to each class of shares are calculated in the same manner and at the same time, except that net investment income dividends to Class A, Class C, Class R and Class Y shares can reflect different transfer agent and distribution expense rates.

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G. Risks

The value of securities held by the Fund may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic, political or regulatory conditions, recessions, the spread of infectious illness or other public health issues, inflation, changes in interest rates, armed conflict including Russia’s military invasion of Ukraine, sanctions against Russia, other nations or individuals or companies and possible countermeasures, lack of liquidity in the bond markets or adverse investor sentiment. In the past several years, financial markets have experienced increased volatility, depressed valuations, decreased liquidity and heightened uncertainty. These conditions may continue, recur, worsen or spread. Interest rates are very low, which means there is more risk that they may go up. The U.S. Federal Reserve has recently started to raise certain interest rates. A general rise in interest rates could adversely affect the price and liquidity of fixed-income securities and could also result in increased redemptions from the Fund. Rates of inflation have recently risen. The value of assets or income from an investment may be worth less in the future as inflation decreases the value of money. As inflation increases, the real value of the Fund’s assets can decline as can the value of the Fund’s distributions.

The global pandemic of the novel coronavirus respiratory disease designated COVID-19 has resulted in major disruption to economies and markets around the world, including the United States. Global financial markets have experienced extreme volatility and severe losses, and trading in many instruments has been disrupted. Liquidity for many instruments has been greatly reduced for periods of time. Some sectors of the economy and individual issuers have experienced particularly large losses. These circumstances may continue for an extended period of time, and may continue to affect adversely the value and liquidity of the Fund’s investments. Following Russia’s recent invasion of Ukraine, Russian securities have lost all, or nearly all, their market value. Other securities or markets could be similarly affected by past or future geopolitical or other events or conditions.

Governments and central banks, including the U.S. Federal Reserve, have taken extraordinary and unprecedented actions to support local and global economies and the financial markets. These actions have resulted in significant expansion of public debt, including in the U.S. The consequences of high public debt, including its future impact on the economy and securities markets, may not be known for some time.

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The Fund’s investments in foreign markets and countries with limited developing markets may subject the Fund to a greater degree of risk than investments in a developed market. These risks include disruptive political or economic conditions, military conflicts and sanctions, terrorism, sustained economic downturns, financial instability, reduction of government or central bank support, inadequate accounting standards, tariffs, tax disputes or other tax burdens, nationalization or expropriation of assets, and the imposition of adverse governmental laws, arbitrary application of laws and regulations or lack of rule of law, or currency exchange restrictions.

Russia launched a large-scale invasion of Ukraine on February 24, 2022. In response to the military action by Russia, various countries, including the U.S., the United Kingdom, and European Union issued broad-ranging economic sanctions against Russia and Belarus and certain companies and individuals. Since then, Russian securities have lost all, or nearly all, their market value, and many other issuers, securities and markets have been adversely affected. The United States and other countries may impose sanctions on other countries, companies and individuals in light of Russia’s military invasion. The extent and duration of the military action or future escalation of such hostilities, the extent and impact of existing and future sanctions, market disruptions and volatility, and the result of any diplomatic negotiations cannot be predicted. These and any related events could have a significant impact on the value and liquidity of certain Fund investments, on Fund performance and the value of an investment in the Fund, particularly with respect to securities and commodities, such as oil and natural gas, as well as other sectors with exposure to Russian issuers or issuers in other countries affected by the invasion, and are likely to have collateral impacts on market sectors globally.

The Fund invests in below-investment-grade (high-yield) debt securities and preferred stocks. Some of these high-yield securities may be convertible into equity securities of the issuer. Debt securities rated below-investment-grade are commonly referred to as “junk bonds” and are considered speculative with respect to the issuer’s capacity to pay interest and repay principal. These securities involve greater risk of loss, are subject to greater price volatility, and may be less liquid and more difficult to value, especially during periods of economic uncertainty or change, than higher rated debt securities.

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The Fund’s investments, payment obligations and financing terms may be based on floating rates, such as LIBOR (London Interbank Offered Rate). ICE Benchmark Administration, the administrator of LIBOR, ceased publication of most LIBOR settings on a representative basis at the end of 2021 and is expected to cease publication of a majority of U.S. dollar LIBOR settings on a representative basis after June 30, 2023. In addition, global regulators have announced that, with limited exceptions, no new LIBOR-based contracts should be entered into after 2021. Actions by regulators have resulted in the establishment of alternative reference rates to LIBOR in most major currencies. Markets are developing in response to these new rates, but questions around liquidity in these rates and how to appropriately adjust these rates to eliminate any economic value transfer at the time of transition remain a significant concern. The effect of any changes to - or discontinuation of - LIBOR on the Fund will vary depending on, among other things, existing fallback provisions in individual contracts and whether, how, and when industry participants develop and widely adopt new reference rates and fallbacks for both legacy and new products and instruments. In March, 2022, the U.S. federal government enacted legislation to establish a process for replacing LIBOR in existing contracts that do not already provide for the use of a clearly defined or practicable replacement benchmark rate as described in the legislation. Generally speaking, for contracts that do not contain a fallback provision as described in the legislation, a benchmark replacement recommended by the Federal Reserve Board will effectively automatically replace the USD LIBOR benchmark in the contract after June 30, 2023. The recommended benchmark replacement will be based on the Secured Overnight Financing Rate (SOFR) published by the Federal Reserve Bank of New York, including any recommended spread adjustment and benchmark replacement conforming changes. The process of transitioning from LIBOR may involve, among other things, increased volatility or illiquidity in markets for instruments that rely on LIBOR. The transition may also result in a reduction in the value of certain LIBOR-based investments held by the Fund or reduce the effectiveness of related transactions such as hedges.

Any such effects of the transition away from LIBOR, as well as other unforeseen effects, could result in losses for the Fund. Because the usefulness of LIBOR as a benchmark may deteriorate during the transition period, these effects could occur at any time.

With the increased use of technologies such as the Internet to conduct business, the Fund is susceptible to operational, information security and related risks. While the Fund’s Adviser has established business continuity plans in the event of, and risk management systems to prevent, limit or mitigate, such cyber-attacks, there are inherent limitations in such plans

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and systems, including the possibility that certain risks have not been identified. Furthermore, the Fund cannot control the cybersecurity plans and systems put in place by service providers to the Fund such as the Fund’s custodian and accounting agent, and the Fund’s transfer agent. In addition, many beneficial owners of Fund shares hold them through accounts at broker-dealers, retirement platforms and other financial market participants over which neither the Fund nor the Adviser exercises control. Each of these may in turn rely on service providers to them, which are also subject to the risk of cyber-attacks. Cybersecurity failures or breaches at the Adviser or the Fund’s service providers or intermediaries have the ability to cause disruptions and impact business operations, potentially resulting in financial losses, interference with the Fund’s ability to calculate its net asset value, impediments to trading, the inability of Fund shareowners to effect share purchases, redemptions or exchanges or receive distributions, loss of or unauthorized access to private shareowner information and violations of applicable privacy and other laws, regulatory fines, penalties, reputational damage, or additional compliance costs. Such costs and losses may not be covered under any insurance. In addition, maintaining vigilance against cyber-attacks may involve substantial costs over time, and system enhancements may themselves be subject to cyber-attacks.

H. Restricted Securities

Restricted Securities are subject to legal or contractual restrictions on resale. Restricted securities generally are resold in transactions exempt from registration under the Securities Act of 1933. Private placement securities are generally considered to be restricted except for those securities traded between qualified institutional investors under the provisions of Rule 144A of the Securities Act of 1933.

Disposal of restricted investments may involve negotiations and expenses, and prompt sale at an acceptable price may be difficult to achieve. Restricted investments held by the Fund at April 30, 2022 are listed in the Schedule of Investments.

I. Insurance-Linked Securities (“ILS”)

The Fund invests in ILS. The Fund could lose a portion or all of the principal it has invested in an ILS, and the right to additional interest or dividend payments with respect to the security, upon the occurrence of one or more trigger events, as defined within the terms of an insurance-linked security. Trigger events, generally, are hurricanes, earthquakes, or other natural events of a specific size or magnitude that occur in a designated geographic region during a specified time period, and/or that involve losses or other

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metrics that exceed a specific amount. There is no way to accurately predict whether a trigger event will occur, and accordingly, ILS carry significant risk. The Fund is entitled to receive principal, and interest and/or dividend payments so long as no trigger event occurs of the description and magnitude specified by the instrument. In addition to the specified trigger events, ILS may expose the Fund to other risks, including but not limited to issuer (credit) default, adverse regulatory or jurisdictional interpretations and adverse tax consequences.

The Fund’s investments in ILS may include event-linked bonds. ILS also may include special purpose vehicles (“SPVs”) or similar instruments structured to comprise a portion of a reinsurer’s catastrophe-oriented business, known as quota share instruments (sometimes referred to as reinsurance sidecars), or to provide reinsurance relating to specific risks to insurance or reinsurance companies through a collateralized instrument, known as collateralized reinsurance. Structured reinsurance investments also may include industry loss warranties (“ILWs”). A traditional ILW takes the form of a bilateral reinsurance contract, but there are also products that take the form of derivatives, collateralized structures, or exchange-traded instruments.

Where the ILS are based on the performance of underlying reinsurance contracts, the Fund has limited transparency into the individual underlying contracts, and therefore must rely upon the risk assessment and sound underwriting practices of the issuer. Accordingly, it may be more difficult for the Adviser to fully evaluate the underlying risk profile of the Fund’s structured reinsurance investments, and therefore the Fund’s assets are placed at greater risk of loss than if the Adviser had more complete information. Structured reinsurance instruments generally will be considered illiquid securities by the Fund. These securities may be difficult to purchase, sell or unwind. Illiquid securities also may be difficult to value. If the Fund is forced to sell an illiquid asset, the Fund may be forced to sell at a loss.

J. Credit Default Swap Contracts

A credit default swap is a contract between a buyer of protection and a seller of protection against a pre-defined credit event or an underlying reference obligation, which may be a single security or a basket or index of securities. The Fund may buy or sell credit default swap contracts to seek to increase the Fund’s income, or to attempt to hedge the risk of default on portfolio securities. A credit default swap index is used to hedge risk or take a position on a basket of credit entities or indices.

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As a seller of protection, the Fund would be required to pay the notional (or other agreed-upon) value of the referenced debt obligation to the counterparty in the event of a default by a U.S. or foreign corporate issuer of a debt obligation, which would likely result in a loss to the Fund. In return, the Fund would receive from the counterparty a periodic stream of payments during the term of the contract, provided that no event of default occurred. The maximum exposure of loss to the seller would be the notional value of the credit default swaps outstanding. If no default occurs, the Fund would keep the stream of payments and would have no payment obligation. The Fund may also buy credit default swap contracts in order to hedge against the risk of default of debt securities, in which case the Fund would function as the counterparty referenced above.

As a buyer of protection, the Fund makes an upfront or periodic payment to the protection seller in exchange for the right to receive a contingent payment. An upfront payment made by the Fund, as the protection buyer, is recorded within the “Swap contracts, at value” line item on the Statement of Assets and Liabilities. Periodic payments received or paid by the Fund are recorded as realized gains or losses on the Statement of Operations.

Credit default swap contracts are marked-to-market daily using valuations supplied by independent sources, and the change in value, if any, is recorded within the “Swap contracts, at value” line item on the Statement of Assets and Liabilities. Payments received or made as a result of a credit event or upon termination of the contract are recognized, net of the appropriate amount of the upfront payment, as realized gains or losses on the Statement of Operations.

Credit default swap contracts involving the sale of protection may involve greater risks than if the Fund had invested in the referenced debt instrument directly. Credit default swap contracts are subject to general market risk, liquidity risk, counterparty risk and credit risk. If the Fund is a protection buyer and no credit event occurs, it will lose its investment. If the Fund is a protection seller and a credit event occurs, the value of the referenced debt instrument received by the Fund, together with the periodic payments received, may be less than the amount the Fund pays to the protection buyer, resulting in a loss to the Fund. In addition, obligations under sell protection credit default swaps may be partially offset by net amounts received from settlement of buy protection credit default swaps entered into by the Fund for the same reference obligation with the same counterparty.

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Certain swap contracts that are cleared through a central clearinghouse are referred to as centrally cleared swaps. All payments made or received by the Fund are pursuant to a centrally cleared swap contract with the central clearing party rather than the original counterparty. Upon entering into a centrally cleared swap contract, the Fund is required to make an initial margin deposit, either in cash or in securities. The daily change in value on open centrally cleared contracts is recorded as “Variation margin for centrally cleared swap contracts” on the Statement of Assets and Liabilities. Cash received from or paid to the broker related to previous margin movement is held in a segregated account at the broker and is recorded as either “Due from broker for swaps” or “Due to broker for swaps” on the Statement of Assets and Liabilities. The amount of cash deposited with a broker as collateral at April 30, 2022, is recorded as “Swaps collateral” on the Statement of Assets and Liabilities.

The average market value of credit default swap contracts open during the six months ended April 30, 2022, was $(2,557,219). Open credit default swap contracts at April 30, 2022, are listed in the Schedule of Investment.

2. Management Agreement

The Adviser manages the Fund’s portfolio. Management fees are calculated daily and paid monthly at the annual rate of 0.70% of the Fund’s average daily net assets up to $500 million, 0.65% of the next $500 million of the Fund’s average daily net assets, 0.60% of the next $4 billion of the Fund’s average daily net assets, 0.55% of the next $1 billion, 0.50% of the next $1 billion of the Fund’s average daily net assets, 0.45% of the next $1 billion of the Fund’s average daily net assets, 0.40% of the next $1 billion of the Fund’s average daily net assets, 0.35% of the next $1 billion of the Fund’s average daily net assets, and 0.30% of the Fund’s average daily net assets over $10 billion. For the six months ended April 30, 2022, the effective management fee (excluding waivers and/or assumption of expenses) was equivalent to 0.69% (annualized) of the Fund’s average daily net assets.

The Adviser has contractually agreed to limit ordinary operating expenses (ordinary operating expenses means all fund expenses other than taxes, brokerage commissions, acquired fund fees and expenses and extraordinary expenses, such as litigation) of the Fund to the extent required to reduce Fund expenses to 1.10% and 0.85% of the average daily net assets attributable to Class A and Class Y shares, respectively. These expense limitations are in effect through March 1, 2023. There can be no assurance that the Adviser will extend the expense limitation agreement for a class of shares beyond the date referred to above. Fees waived and expenses reimbursed during the six months ended April 30, 2022 are reflected on the Statement of Operations.

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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 $58,748 in management fees, administrative costs and certain other reimbursements payable to the Adviser at April 30, 2022.

3. Compensation of Trustees and Officers

The Fund pays an annual fee to its Trustees. The Adviser reimburses the Fund for fees paid to the Interested Trustees. The Fund does not pay any salary or other compensation to its officers. For the six months ended April 30, 2022, the Fund paid $12,568 in Trustees’ compensation, which is reflected on Statement of Operations as Trustees’ fees. At April 30, 2022, the Fund had a payable for Trustees’ fees on its Statement of Assets and Liabilities of $1,968.

4. Transfer Agent

For the period from November 1, 2021 to November 21, 2021, DST Asset Manager Solutions, Inc. served as the transfer agent to the Fund at negotiated rates. Effective November 22, 2021, BNY Mellon Investment Servicing (US) Inc. serves as the transfer agent to the Fund at negotiated rates. Transfer agent fees and payables shown on the Statement of Operations and the Statement of Assets and Liabilities, respectively, include sub-transfer agent expenses incurred through the Fund’s omnibus relationship contracts.

In addition, the Fund reimbursed the transfer agent for out-of-pocket expenses incurred by the transfer agent related to shareowner communications activities such as proxy and statement mailings, and outgoing phone calls. For the six months ended April 30, 2022, such out-of-pocket expenses by class of shares were as follows:

Shareowner Communications:
Class A	$41,157
Class C	2,737
Class R	809
Class Y	3,787
Total	$48,490

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5. Distribution and Service Plans

The Fund has adopted a distribution plan (the “Plan”) pursuant to Rule 12b-1 of the Investment Company Act of 1940 with respect to its Class A, Class C and Class R shares. Pursuant to the Plan, the Fund pays the Distributor 0.25% of the Fund’s average daily net assets attributable to Class A shares as compensation for personal services and/or account maintenance services or distribution services with regard to Class A shares. Pursuant to the Plan, the Fund also pays the Distributor 1.00% of the average daily net assets attributable to Class C shares. The fee for Class C shares consists of a 0.25% service fee and a 0.75% distribution fee paid as compensation for personal services and/or account maintenance services or distribution services with regard to Class C shares. Pursuant to the Plan, the Fund further pays the Distributor 0.50% of the average daily net assets attributable to Class R shares for distribution services. Included in “Due to affiliates” reflected on the Statement of Assets and Liabilities is $11,553 in distribution fees payable to the Distributor at April 30, 2022.

The Fund also has adopted a separate service plan for Class R shares (the “Service Plan”). The Service Plan authorizes the Fund to pay securities dealers, plan administrators or other service organizations that agree to provide certain services to retirement plans or plan participants holding shares of the Fund a service fee of up to 0.25% of the Fund’s average daily net assets attributable to Class R shares held by such plans.

In addition, redemptions of Class A and Class C shares may be subject to a contingent deferred sales charge (“CDSC”). A CDSC of 1.00% may be imposed on redemptions of certain net asset value purchases of Class A shares within 12 months of purchase. Redemptions of Class C shares within 12 months of purchase are subject to a CDSC of 1.00% based on the lower of cost or market value of shares being redeemed. Shares purchased as part of an exchange remain subject to any CDSC that applied to the original purchase of those shares. There is no CDSC for Class R or Class Y shares. Proceeds from the CDSCs are paid to the Distributor. For the six months ended April 30, 2022, CDSCs in the amount of $563 were paid to the Distributor.

6. Line of Credit Facility

The Fund, along with certain other funds in the Pioneer Family of Funds, participates in a committed, unsecured revolving line of credit (“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

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credit facility or the limits set for borrowing by the Fund’s prospectus and the 1940 Act. Effective February 2, 2022, the Fund participates in a credit facility in the amount of $380 million. Prior to February 2, 2022 the Fund participated in a facility in the amount of $450 million. Under such credit facility, depending on the type of loan, interest on borrowings is payable at the London Interbank Offered Rate (“LIBOR”) plus a credit spread. The Fund also pays both an upfront fee and an annual commitment fee to participate in the credit facility. The upfront fee in the amount of 0.10% of the total credit facility and the commitment fee in the amount of 0.25% of the daily unused portion of each lender’s commitment are allocated among participating funds based on an allocation schedule set forth in the credit agreement. For the six months ended April 30, 2022, the Fund had no borrowings under the credit facility.

7. Additional Disclosures about Derivative Instruments and Hedging Activities

The Fund’s use of derivatives may enhance or mitigate the Fund’s exposure to the following risks:

Interest rate risk relates to the fluctuations in the value of interest-bearing securities due to changes in the prevailing levels of market interest rates.

Credit risk relates to the ability of the issuer of a financial instrument to make further principal or interest payments on an obligation or commitment that it has to the Fund.

Foreign exchange rate risk relates to fluctuations in the value of an asset or liability due to changes in currency exchange rates.

Equity risk relates to the fluctuations in the value of financial instruments as a result of changes in market prices (other than those arising from interest rate risk or foreign exchange rate risk), whether caused by factors specific to an individual investment, its issuer, or all factors affecting all instruments traded in a market or market segment.

Commodity risk relates to the risk that the value of a commodity or commodity index will fluctuate based on increases or decreases in the commodities market and factors specific to a particular industry or commodity.

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The fair value of open derivative instruments (not considered to be hedging instruments for accounting disclosure purposes) by risk exposure at April 30, 2022, was as follows:

Statement of Assets and Liabilities
			Foreign
	Interest	Credit	Exchange	Equity	Commodity
	Rate Risk	Risk	Rate Risk	Risk	Risk
Liabilities
Swap contracts at value	$ —	$599,956	$ —	$ —	$ —
Total Value	$ —	$599,956	$ —	$ —	$ —

The effect of derivative instruments (not considered to be hedging instruments for accounting disclosure purposes) on the Statement of Operations by risk exposure at April 30, 2022 was as follows:

Statement of Operations

			Foreign
	Interest	Credit	Exchange	Equity	Commodity
	Rate Risk	Risk	Rate Risk	Risk	Risk
Net Realized Gain (Loss) on
Swap contracts	$ —	$(4,427,748)	$ —	$ —	$ —
Total Value	$ —	$(4,427,748)	$ —	$ —	$ —

Change in Net Unrealized
Appreciation
(Depreciation) on
Swap contracts	$ —	$ 5,682,436	$ —	$ —	$ —
Total Value	$ —	$ 5,682,436	$ —	$ —	$ —

8. Unfunded Loan Commitments

The Fund may enter into unfunded loan commitments. Unfunded loan commitments may be partially or wholly unfunded. During the contractual period, the Fund is obliged to provide funding to the borrower upon demand. A fee is earned by the Fund on the unfunded loan commitment and is recorded as interest income on the Statement of Operations. Unfunded loan commitments are fair valued in accordance with the valuation policy described in Footnote 1A and unrealized appreciation or depreciation, if any, is recorded on the Statement of Assets and Liabilities.

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As of April 30, 2022, the Fund had the following unfunded loan commitments outstanding:


				Unrealized
				Appreciation
Loan	Principal	Cost	Value	(Depreciation)
Project Watson Bridge Loan	$6,085,200	$6,085,200	$6,085,200	$ —
Total Value	$6,085,200	$6,085,200	$6,085,200	$ —

9. Changes in Custodian and Sub-Administrator, and Transfer Agent

Effective November 22, 2021, The Bank of New York Mellon Corporation (“BNY Mellon”) serves as the Fund’s Custodian and Sub-Administrator.

Effective November 22, 2021, BNY Mellon Investment Servicing (US) Inc. serves as the Fund’s shareholder servicing and transfer agent.

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Trustees, Officers and Service Providers

Trustees	Officers
Thomas J. Perna, Chairman	Lisa M. Jones, President and
John E. Baumgardner, Jr.	Chief Executive Officer
Diane Durnin	Anthony J. Koenig, Jr., Treasurer
Benjamin M. Friedman	and Chief Financial and
Lisa M. Jones	Accounting Officer
Craig C. MacKay	Christopher J. Kelley, Secretary and
Lorraine H. Monchak	Chief Legal Officer
Marguerite A. Piret
Fred J. Ricciardi
Kenneth J. Taubes

Investment Adviser and Administrator
Amundi Asset Management US, Inc.

Custodian and Sub-Administrator
The Bank of New York Mellon Corporation

Independent Registered Public Accounting Firm
Ernst & Young LLP

Principal Underwriter
Amundi Distributor US, Inc.

Legal Counsel
Morgan, Lewis & Bockius LLP

Transfer Agent
BNY Mellon Investment Servicing (US) Inc.

Proxy Voting Policies and Procedures of the Fund are available without charge, upon request, by calling our toll free number (1-800-225-6292). Information regarding how the Fund voted proxies relating to portfolio securities during the most recent 12-month period ended June 30 is publicly available to shareowners at www.amundi.com/us. This information is also available on the Securities and Exchange Commission’s web site at www.sec.gov.

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How to Contact Amundi

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^SMfor automated fund yields, prices,
account information and transactions	1-800-225-4321
Retirement plans information	1-800-622-0176

Write to us:

Amundi
P.O. Box 9897
Providence, R.I. 02940-8097

Our toll-free fax	1-800-225-4240
Our internet e-mail address	us.askamundi@amundi.com/us
(for general questions about Amundi only)

Visit our web site: www.amundi.com/us.

This report must be preceded or accompanied by a prospectus.

The Fund files a complete schedule of portfolio holdings with the Securities and Exchange Commission for the first and third quarters of each fiscal year as an exhibit to its reports on Form N-PORT. Shareholders may view the filed Form N-PORT by visiting the Commission’s web site at https://www.sec.gov.

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Amundi Asset Management US, Inc.
60 State Street
Boston, MA 02109
www.amundi.com/us

Securities offered through Amundi Distributor US, Inc.,
60 State Street, Boston, MA 02109
Underwriter of Pioneer Mutual Funds, Member SIPC
© 2022 Amundi Asset Management US, Inc. 19383-16-0622

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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

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enumerated in paragraph (b) of this Item by posting such information on its Internet website, disclose the registrant’s Internet address and such intention.

Not applicable.

(f) The registrant must:

(1) File with the Commission, pursuant to Item 12(a)(1), a copy of its code of ethics that applies to the registrant’s principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions, as an exhibit to its annual report on this Form N-CSR (see attachment);

(2) Post the text of such code of ethics on its Internet website and disclose, in its most recent report on this Form N-CSR, its Internet address and the fact that it has posted such code of ethics on its Internet website; or

(3) Undertake in its most recent report on this Form N-CSR to provide to any person without charge, upon request, a copy of such code of ethics and explain the manner in which such request may be made. See Item 10(2)

ITEM 3. AUDIT COMMITTEE FINANCIAL EXPERT.

(a) (1) Disclose that the registrant’s Board of Trustees has determined that the registrant either:

(i) Has at least one audit committee financial expert serving on its audit committee; or

(ii) Does not have an audit committee financial expert serving on its audit committee.

The registrant’s Board of Trustees has determined that the registrant has at least one audit committee financial expert.

(2) If the registrant provides the disclosure required by paragraph (a)(1)(i) of this Item, it must disclose the name of the audit committee financial expert and whether that person is “independent.” In order to be considered “independent” for purposes of this Item, a member of an audit committee may not, other than in his or her capacity as a member of the audit committee, the Board of Trustees, or any other board committee:

(i) Accept directly or indirectly any consulting, advisory, or other compensatory fee from the issuer; or

(ii) Be an “interested person” of the investment company as defined in Section 2(a)(19) of the Act (15 U.S.C. 80a-2(a)(19)).

Mr. Fred J. Ricciardi, 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.

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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 Amundi Asset Management US, Inc., 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.

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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.

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SECTION II - POLICY

SERVICE CATEGORY	SERVICE CATEGORY DESCRIPTION		SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES

I. AUDIT SERVICES	Services that are directly		o Accounting research assistance
	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. AUDIT-RELATED	Services which are not		o AICPA attest and agreed-upon procedures
SERVICES	prohibited under Rule		o Technology control assessments
	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.

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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”

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SECTION III - POLICY DETAIL, CONTINUED


SERVICE CATEGORY	SERVICE CATEGORY DESCRIPTION	SPECIFIC PRE-APPROVED SERVICE
		SUBCATEGORIES
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”

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SECTION III - POLICY DETAIL, CONTINUED


SERVICE CATEGORY	SERVICE CATEGORY DESCRIPTION	SPECIFIC PRE-APPROVED SERVICE
		SUBCATEGORIES
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”

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SECTION III - POLICY DETAIL, CONTINUED


SERVICE CATEGORY	SERVICE CATEGORY DESCRIPTION	SPECIFIC PROHIBITED SERVICE
		SUBCATEGORIES
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.

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GENERAL AUDIT COMMITTEE APPROVAL POLICY:

o For all projects, the officers of the Funds and the Fund’s auditors will each make an assessment to determine that any proposed projects will not impair independence.

o Potential services will be classified into the four non-restricted service categories and the “Approval of Audit, Audit-Related, Tax and Other Services” Policy above will be applied. Any services outside the specific pre-approved service subcategories set forth above must be specifically approved by the Audit Committee.

o At least quarterly, the Audit Committee shall review a report summarizing the services by service category, including fees, provided by the Audit firm as set forth in the above policy.

(2) Disclose the percentage of services described in each of paragraphs (b) through (d) of this Item that were approved by the audit committee pursuant to paragraph (c)(7)(i)(C) of Rule 2-01 of Regulation S-X.

N/A

(f) If greater than 50 percent, disclose the percentage of hours expended on the principal accountants engagement to audit the registrant’s financial statements for the most recent fiscal year that were attributed to work performed by persons other than the principal accountant’s full-time, permanent employees.

N/A

(g) Disclose the aggregate non-audit fees billed by the registrants accountant for services rendered to the registrant, and rendered to the registrants investment adviser (not including any sub-adviser whose role is primarily portfolio management and is subcontracted with or overseen by another investment adviser), and any entity controlling, controlled by, or under common control with the adviser that provides ongoing services to the registrant for each of the last two fiscal years of the registrant.

N/A

(h) Disclose whether the registrants audit committee of the Board of Trustees has considered whether the provision of non-audit services that were rendered to the registrants investment adviser (not including any subadviser whose role is primarily portfolio management and is subcontracted with or overseen by another investment adviser), and any entity controlling, controlled by, or under common control with the investment adviser that provides ongoing services to the registrant that were not pre-approved pursuant to paragraph (c)(7)(ii) of Rule 2-01 of Regulation S-X is compatible with maintaining the principal accountant’s independence.

The Fund’s audit committee of the Board of Trustees has considered whether the provision of non-audit services that were rendered to the Affiliates (as defined) that were not pre- approved pursuant to paragraph (c)(7)(ii) of Rule 2-01 of Regulation S-X is compatible with maintaining the principal accountant’s independence.

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ITEM 5. AUDIT COMMITTEE OF LISTED REGISTRANTS

(a) If the registrant is a listed issuer as defined in Rule 10A-3 under the Exchange Act (17 CFR 240.10A-3), state whether or not the registrant has a separately-designated standing audit committee established in accordance with Section 3(a)(58)(A) of the Exchange Act (15 U.S.C. 78c(a)(58)(A)). If the registrant has such a committee, however designated, identify each committee member. If the entire board of directors is acting as the registrant’s audit committee as specified in Section 3(a)(58)(B) of the Exchange Act (15 U.S.C. 78c(a)(58)(B)), so state.

N/A

(b) If applicable, provide the disclosure required by Rule 10A-3(d) under the Exchange Act (17 CFR 240.10A-3(d)) regarding an exemption from the listing standards for audit committees.

N/A

ITEM 6. SCHEDULE OF INVESTMENTS.

File Schedule of Investments in securities of unaffiliated issuers as of the close of the reporting period as set forth in 210.1212 of Regulation S-X [17 CFR 210.12-12], unless the schedule is included as part of the report to shareholders filed under Item 1 of this Form.

Included in Item 1

ITEM 7. DISCLOSURE OF PROXY VOTING POLICIES AND PROCEDURES FOR CLOSED-END MANAGEMENT INVESTMENT COMPANIES.

A closed-end management investment company that is filing an annual report on this Form N-CSR must, unless it invests exclusively in non-voting securities, describe the policies and procedures that it uses to determine how to vote proxies relating to portfolio securities, including the procedures that the company uses when a vote presents a conflict between the interests of its shareholders, on the one hand, and those of the company’s investment adviser; principal underwriter; or any affiliated person (as defined in Section 2(a)(3) of the Investment Company Act of 1940 (15 U.S.C. 80a-2(a)(3)) and the rules thereunder) of the company, its investment adviser, or its principal underwriter, on the other. Include any policies and procedures of the company’s investment adviser, or any other third party, that the company uses, or that are used on the company’s behalf, to determine how to vote proxies relating to portfolio securities.

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ITEM 8. PORTFOLIO MANAGERS OF CLOSED-END MANAGEMENT INVESTMENT COMPANIES.

(a) If the registrant is a closed-end management investment company that is filing an annual report on this Form N-CSR, provide the following information:

(1) State the name, title, and length of service of the person or persons employed by or associated with the registrant or an investment adviser of the registrant who are primarily responsible for the day-to-day management of the registrant’s portfolio (“Portfolio Manager”). Also state each Portfolio Manager’s business experience during the past 5 years.

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ITEM 9. PURCHASES OF EQUITY SECURITIES BY CLOSED-END MANAGEMENT INVESTMENT COMPANY AND AFFILIATED PURCHASERS.

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(a) If the registrant is a closed-end management investment company, in the following tabular format, provide the information specified in paragraph (b) of this Item with respect to any purchase made by or on behalf of the registrant or any affiliated purchaser, as defined in Rule 10b-18(a)(3) under the Exchange Act (17 CFR 240.10b-18(a)(3)), of shares or other units of any class of the registrant’s equity securities that is registered by the registrant pursuant to Section 12 of the Exchange Act (15 U.S.C. 781).

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ITEM 10. SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS.

Describe any material changes to the procedures by which shareholders may recommend nominees to the registrant’s board of directors, where those changes were implemented after the registrant last provided disclosure in response to the requirements of Item 407(c)(2)(iv) of Regulation S-R(17 CFR 229.407)(as required by Item 22(b)(15)) of Schedule 14A (17 CFR 240.14a-101), or this Item.

There have been no material changes to the procedures by which the shareholders may recommend nominees to the registrant’s board of directors since the registrant last provided disclosure in response to the requirements of Item 407(c)(2)(iv) of Regulation S-R of Schedule 14(A) in its definitive proxy statement, or this item.

ITEM 11. CONTROLS AND PROCEDURES.

(a) Disclose the conclusions of the registrant’s principal executive and principal financials officers, or persons performing similar functions, regarding the effectiveness of the registrant’s disclosure controls and procedures (as defined in Rule 30a-3(c) under the Act (17 CFR 270.30a-3(c))) as of a date within 90 days of the filing date of the report that includes the disclosure required by this paragraph, based on the evaluation of these controls and procedures required by Rule 30a-3(b) under the Act (17 CFR 270.30(a)-3(b) and Rules 13a-15(b) or 15d-15(b) under the Exchange Act (17 CFR 240.13a-15(b) or 240.15d-15(b)).

The registrant’s principal executive officer and principal financial officer have concluded that the registrant’s disclosure controls and procedures are effective based on the evaluation of these controls and procedures as of a date within 90 days of the filing date of this report.

(b) Disclose any change in the registrant’s internal control over financial reporting (as defined in Rule 30a-3(d) under the Act (17CFR 270.30a-3(d)) that occured during the second fiscal quarter of the period covered by this report that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting.

There were no significant changes in the registrant’s internal control over financial reporting that occurred during the second fiscal quarter of the period covered by this report that have materially affected, or are reasonably likely to materially affect, the registrant’s internal control over financial reporting.

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Item 12. Disclosure of Securities Lending Activities for Closed-End Management Investment Companies.

(a) If the registrant is a closed-end management investment company, provide the following dollar amounts of income and compensation related to the securities lending activities of the registrant during its most recent fiscal year:

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(1) Gross income from securities lending activities;

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(2) All fees and/or compensation for each of the following securities lending activities and related services: any share of revenue generated by the securities lending program paid to the securities lending agent(s) (revenue split); fees paid for cash collateral management services (including fees deducted from a pooled cash collateral reinvestment vehicle) that are not included in the revenue split; administrative fees that are not included in the revenue split; fees for indemnification that are not included in the revenue split; rebates paid to borrowers; and any other fees relating to the securities lending program that are not included in the revenue split, including a description of those other fees;

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(3) The aggregate fees/compensation disclosed pursuant to paragraph (2); and

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(4) Net income from securities lending activities (i.e., the dollar amount in paragraph (1) minus the dollar amount in paragraph (3)).

If a fee for a service is included in the revenue split, state that the fee is included in the revenue split.

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(b) If the registrant is a closed-end management investment company, describe the services provided to the registrant by the securities lending agent in the registrants most recent fiscal year.

N/A

ITEM 13. EXHIBITS.

(a) File the exhibits listed below as part of this Form. Letter or number the exhibits in the sequence indicated.

(1) Any code of ethics, or amendment thereto, that is the subject of the disclosure required by Item 2, to the extent that the registrant intends to satisfy the Item 2 requirements through filing of an exhibit.

(2) A separate certification for each principal executive officer and principal financial officer of the registrant as required by Rule 30a-2(a) under the Act (17 CFR 270.30a-2(a)) , exactly as set forth below:

Filed herewith.

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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 High Yield Fund

By (Signature and Title)* /s/ Lisa M. Jones

Lisa M. Jones, President and Chief Executive Officer

Date June , 2022

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

By (Signature and Title)* /s/ Lisa M. Jones

Lisa M. Jones, President and Chief Executive Officer

Date June , 2022

By (Signature and Title)* /s/ Anthony J. Koenig, Jr.

Anthony J. Koenig, Jr., Managing Director, Chief Operations Officer & Treasurer of the Funds

Date June , 2022

* Print the name and title of each signing officer under his or her signature.

Pioneer High Yield Fund N-CSRSCertified semi-annual shareholder report (management investment company)