Edgar Filing: Voya PRIME RATE TRUST

VOYA PRIME RATE TRUST

(the “Trust”)

VOYA SENIOR INCOME FUND

(the “Fund”)

Supplement dated September 30, 2015

to the current Prospectuses

for the above named Fund and Trust

Voya Prime Rate Trust

Effective immediately, the section entitled “How Shares are Priced” in the Trust’s Prospectus is hereby deleted and replaced with the following to reflect changes in the Trust’s valuation procedures and the time the net asset value is determined upon an early closure of the New York Stock Exchange:

HOW SHARES ARE PRICED

The Trust is open for business every day the New York Stock Exchange (“NYSE”) opens for regular trading (each such day, a “Business Day”). The net asset value (“NAV”) per Common Share of the Trust is determined each Business Day as of the close of the regular trading session (“Market Close”), as determined by the Consolidated Tape Association (“CTA”), the central distributor of transaction prices for exchange-traded securities (normally 4:00 p.m. Eastern time unless otherwise designated by the CTA). The NAV per Common Share of the Trust is calculated by dividing the value of the Trust’s loan assets plus all cash and other assets (including accrued expenses but excluding capital and surplus) attributable to the Common Shares by the number of Common Shares outstanding. The NAV per Common Share is made available for publication. On days when the Trust is closed for business, Trust shares will not be priced and the Trust does not transact purchase and redemption orders. To the extent the Trust’s assets are traded in other markets on days when the Trust does not price its shares, the value of the Trust’s assets will likely change and you will not be able to purchase or redeem shares of the Trust.

Assets for which market quotations are readily available are valued at market value. A security listed or traded on an exchange is valued at its last sales price or official closing price as of the close of the regular trading session on the exchange where the security is principally traded or, if such price is not available, at the last sale price as of the Market Close for such security provided by the CTA. Bank loans are valued at the average of the averages of the bid and ask prices provided to an independent loan pricing service by brokers. Futures contracts are valued at the final settlement price set by an exchange on which they are principally traded. Listed options are valued at the mean between the last bid and ask prices from the exchange on which they are principally traded. Investments in open-end registered investment companies that do not trade on an exchange are valued at the end of day NAV per share. Investments in registered investment companies that trade on an exchange are valued at the last sales price or official closing price as of the close of the regular trading session on the exchange where the security is principally traded.

When a market quotation is not readily available or is deemed unreliable, the Trust will determine a fair value for the relevant asset in accordance with procedures adopted by the Trust’s Board. Such procedures provide, for example, that:

Exchange-traded securities are valued at the mean of the closing bid and ask.

Debt obligations are valued using an evaluated price provided by an independent pricing service. Evaluated prices provided by the pricing service may be determined without exclusive reliance on quoted prices, and may reflect factors such as institution-size trading in similar groups of securities, developments related to specific securities, benchmark yield, quality, type of issue, coupon rate, maturity individual trading characteristics and other market data.

Securities traded in the over-the-counter market are valued based on prices provided by independent pricing services or market makers.

Options not listed on an exchange are valued by an independent source using an industry accepted model, such as Black-Scholes.

Centrally cleared swap agreements are valued using a price provided by the central counterparty clearinghouse.

Over-the-counter swap agreements are valued using a price provided by an independent pricing service.

Forward foreign currency contracts are valued utilizing current and forward rates obtained from an independent pricing service. Such prices from the third party pricing service are for specific settlement periods and the Trust’s forward foreign currency contracts are valued at an interpolated rate between the closest preceding and subsequent period reported by the independent pricing service.

Securities for which market prices are not provided by any of the above methods may be valued based upon quotes furnished by brokers.

The prospectuses of the open-end registered investment companies in which the Trust may invest explain the circumstances under which they will use fair value pricing and the effects of using fair value pricing.

Foreign securities’ (including foreign exchange contracts) prices are converted into U.S. dollar amounts using the applicable exchange rates as of Market Close. If market quotations are available and believed to be reliable for foreign exchange-traded equity securities, the securities will be valued at the market quotations. Because trading hours for certain foreign securities end before Market Close, closing market quotations may become unreliable. An independent pricing service determines the degree of certainty, based on historical data, that the closing price in the principal market where a foreign security trades is not the current value as of Market Close. Foreign securities’ prices meeting the approved degree of certainty that the price is not reflective of current value will be valued by the independent pricing service using pricing models designed to estimate likely changes in the values of those securities between the times in which the trading in those securities is substantially completed and Market Close. Multiple factors may be considered by the independent pricing service in determining the value of such securities and may include information relating to sector indices, American Depositary Receipts and domestic and foreign index futures.

All other assets for which market quotations are not readily available or became unreliable (or if the above fair valuation methods are unavailable or determined to be unreliable) are valued at fair value as determined in good faith by or under the supervision of the Board following procedures approved by the Board. Issuer specific events, transaction price, position size, nature and duration of restrictions on disposition of the security, market trends, bid/ask quotes of brokers and other market data may be reviewed in the course of making a good faith determination of a security’s fair value. Valuations change in response to many factors including the historical and prospective earnings of the issuer, the value of the issuer’s assets, general economic conditions, interest rates, investor perceptions and market liquidity. Because of the inherent uncertainties of fair valuation, the values used to determine the Trust’s NAV may materially differ from the value received upon actual sale of those investments. Thus, fair valuation may have an unintended dilutive or accretive effect on the value of shareholders’ investments in the Trust.

Voya Senior Income Fund

Effective immediately, the section entitled “How Shares are Priced” in the Fund’s Prospectus is hereby deleted and replaced with the following to reflect changes in the Fund’s valuation procedures and the time the net asset value is determined upon an early closure of the New York Stock Exchange:

HOW SHARES ARE PRICED

The Fund is open for business every day the New York Stock Exchange (“NYSE”) opens for regular trading (each such day, a “Business Day”). The net asset value (“NAV”) per Common Share of each class of the Fund is determined each Business Day as of the close of the regular trading session (“Market Close”), as determined by the Consolidated Tape Association (“CTA”), the central distributor of transaction prices for exchange-traded securities (normally 4:00 p.m. Eastern time unless otherwise designated by the CTA). The NAV per Common Share of each class of the Fund is calculated by dividing the value of the Fund’s loan assets plus all cash and other assets (including accrued expenses but excluding capital and surplus) attributable to that class of Common Shares by the number of Common Shares outstanding. The NAV per Common Share is made available for publication. On days when the Fund is closed for business, Fund shares will not be priced and the Fund does not transact purchase and redemption orders. To the extent the Fund’s assets are traded in other markets on days when the Fund does not price its shares, the value of the Fund’s assets will likely change and you will not be able to purchase or redeem shares of the Fund.

When a market quotation is not readily available or is deemed unreliable, the Fund will determine a fair value for the relevant asset in accordance with procedures adopted by the Fund’s Board. Such procedures provide, for example, that:

Exchange-traded securities are valued at the mean of the closing bid and ask.

Securities traded in the over-the-counter market are valued based on prices provided by independent pricing services or market makers.

Options not listed on an exchange are valued by an independent source using an industry accepted model, such as Black-Scholes.

Centrally cleared swap agreements are valued using a price provided by the central counterparty clearinghouse.

Over-the-counter swap agreements are valued using a price provided by an independent pricing service.

Forward foreign currency contracts are valued utilizing current and forward rates obtained from an independent pricing service. Such prices from the third party pricing service are for specific settlement periods and the Fund’s forward foreign currency contracts are valued at an interpolated rate between the closest preceding and subsequent period reported by the independent pricing service.

Securities for which market prices are not provided by any of the above methods may be valued based upon quotes furnished by brokers.

The prospectuses of the open-end registered investment companies in which the Fund may invest explain the circumstances under which they will use fair value pricing and the effects of using fair value pricing.

All other assets for which market quotations are not readily available or became unreliable (or if the above fair valuation methods are unavailable or determined to be unreliable) are valued at fair value as determined in good faith by or under the supervision of the Board following procedures approved by the Board. Issuer specific events, transaction price, position size, nature and duration of restrictions on disposition of the security, market trends, bid/ask quotes of brokers and other market data may be reviewed in the course of making a good faith determination of a security’s fair value. Valuations change in response to many factors including the historical and prospective earnings of the issuer, the value of the issuer’s assets, general economic conditions, interest rates, investor perceptions and market liquidity. Because of the inherent uncertainties of fair valuation, the values used to determine the Fund’s NAV may materially differ from the value received upon actual sale of those investments. Thus, fair valuation may have an unintended dilutive or accretive effect on the value of shareholders’ investments in the Fund.

PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE