Supplement dated July 16, 2026

to the currently effective

Summary Prospectus and Prospectus for the

iShares 20+ Year Treasury Bond BuyWrite Strategy ETF (TLTW)

(the “Fund”)

The Board of Trustees has approved the following changes for the Fund that are expected to take effect on or around September 17, 2026, except as noted in Item 2 below (the “Effective Dates”).

Accordingly, the following changes will become effective on the Effective Dates:

The Fund seeks to track the investment results of the Cboe TLT 2% OTM BuyWrite Index (the “Underlying Index”). The Underlying Index is designed to measure the performance of holding the iShares 20+ Year Treasury Bond ETF (“TLT” or the “Underlying Fund”) while writing (selling) call options on the Underlying Fund to generate income. The Underlying Index consists of four tranches of options, each rolling on a weekly staggered schedule. A “Premium Income+” strategy is intended to reflect a focus on generating option premium income versus a greater mix of income and growth.

As of October 31, 2025, a significant portion of the Underlying Index is indirectly represented through its holdings in the Underlying Fund by publicly-issued U.S. Treasury securities. The components of the Underlying Index, including those indirectly represented through its holdings in the Underlying Fund, are likely to change over time.

The Underlying Fund

The Underlying Fund is an ETF that seeks to track the investment results of the ICE^® U.S. Treasury 20+ Year Bond Index (the “Underlying Fund’s underlying index”), which consists of publicly issued U.S. Treasury securities that have a remaining maturity greater than 20 years and have $300 million or more of outstanding face value, excluding amounts held by the Federal Reserve System.

Index constituents also must be fixed-rate and denominated in U.S. dollars. Excluded from the Underlying Fund’s underlying index are inflation-linked securities, Treasury bills, cash management bills, any government agency debt issued with or without a government guarantee, original issue zero‑coupon securities and zero‑coupon issues that have been stripped from coupon-paying bonds. The Underlying Fund’s underlying index is market value weighted, and its constituents are updated on the last calendar day of each month.

BFA is the investment adviser to the Underlying Fund and receives a management fee from the Underlying Fund. Shares of the Underlying Fund are listed on Cboe BZX.

The Written Call Options

The options in the index are referred to generally as Flexible Exchange Options (“FLEX Options”). FLEX Options provide the ability to customize key option contract terms such as strike price, style and expiration date. The Underlying Index utilizes “European-style” call options, meaning they are exercisable at the strike price only on the expiration date. The Underlying Index utilizes four tranches of call options with staggered four-week expiration cycles and each tranche represents an equal share of the Underlying Index. Each call option in the Underlying Index has a strike price equal to 102% of the closing value of the Underlying Fund on the applicable roll date. If, on the business day prior to the applicable

roll date, the premium percentage of the 102% call option is below five basis points of the closing price of the Underlying Fund on such business day, the Underlying Index will instead select a new call option with the strike price equal to 100% of the closing value of the Underlying Fund. The roll date is the day that the Underlying Index settles the expiring call option for the applicable tranche and writes a new call option for that tranche’s new four-week cycle scheduled to expire on the last trading day of the week falling four weeks from that roll date. Each tranche will have a roll date occurring on a different week from any other tranche. The Underlying Index is rebalanced weekly so that each tranche continues to represent an equal share of the Underlying Index at the close of trading on each weekly roll date.

By writing a call option, the Underlying Index receives a premium and gives up the economic exposure to increases in the value of the Underlying Fund above the strike price at expiration. By writing the call options, the Underlying Index will not participate in market gains of the Underlying Fund above the strike price but will fully participate in any market losses if the Underlying Fund declines in value.

Distributions

The Fund expects to make monthly distributions typically consisting of net investment income and amounts attributable to option premiums received by the Fund, generally up to the extrinsic value of such options when traded. The amount of the Fund’s monthly distribution will vary from month to month based on the amount of option premiums received, dividends received from the Underlying Fund and other Fund-specific and market factors. The Fund will also make distributions of net realized securities gains, if any, at least once per year. The Fund is likely to distribute an amount greater than its earnings and profits, resulting in a return of capital.

Indexing Strategy

The Fund seeks to track the investment results of the Underlying Index before fees and expenses of the Fund. BFA uses a representative sampling indexing strategy to manage the Fund. “Representative sampling” is an indexing strategy that involves investing in a representative sample of securities or other instruments intended to collectively have an investment profile similar to that of an applicable underlying index. The instruments selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability and yield) and liquidity measures similar to those of an applicable underlying index. The Fund may or may not hold all of the components of the Underlying Index. The Fund may use derivatives to gain or reduce exposure to the components of the Underlying Index or exposure to one or more market risk factors associated with such components. Subject to the limits described herein, the Fund may purchase and hold cash and cash equivalents, including shares of money market funds advised by BFA or its affiliates, and may also purchase and hold instruments not included in the Underlying Index when BFA believes that such instruments will help the Fund track the performance of the Underlying Index over time, including in light of expected liquidity or trading costs, anticipated additions to or deletions from the Underlying Index, or other reasons as determined by BFA.

The Fund intends for its short option position in the Underlying Fund to be fully offset, or “covered,” by the long position that the Fund holds in shares of the Underlying Fund. At times, however, there may be a notional mismatch due to differences between the Underlying Fund and the RUT with respect to pricing, tracking error, dividends, and other factors. Options written by the Fund are generally expected to be cash-settled upon expiration or closed out through offsetting transactions. The Fund does not expect to physically settle outstanding option positions. In addition, the Fund may write options on different dates than the Underlying Index’s roll date and may use strike prices, contract sizes, or maturity dates that are different than those for the options used in the Underlying Index. The Fund may also write options that are not on the Underlying Fund but that have