Up to $2,100,000,000

8.00% Series A Perpetual Strike Preferred Stock

We have entered into an Omnibus Sales Agreement with TD Securities (USA) LLC, The Benchmark Company, LLC, StoneX Financial Inc., A.G.P./Alliance Global Partners, Barclays Capital Inc., BTIG, LLC, Canaccord Genuity LLC, Cantor Fitzgerald & Co., Clear Street LLC, Compass Point Research & Trading, LLC, H.C. Wainwright & Co., LLC, Keefe, Bruyette & Woods, Inc., Maxim Group LLC, Mizuho Securities USA LLC, Moelis & Company LLC, Morgan Stanley & Co. LLC, Santander US Capital Markets LLC, SG Americas Securities, LLC and TCBI Securities, Inc. doing business as Texas Capital Securities (collectively, the "Agents"), dated November 4, 2025, relating to the sale of shares of our class A common stock, par value $0.001 per share, and shares of several series of our preferred stock, par value $0.001 per share, as amended by Amendment No. 1 to Omnibus Sales Agreement, dated February 19, 2026, and Amendment No. 2 to Omnibus Sales Agreement, dated March 9, 2026 (as so amended and supplemented, the "Sales Agreement").

On March 23, 2026, we entered into an Additional Program Addendum to the Sales Agreement with the Agents relating to the sale of additional shares of our 8.00% Series A Perpetual Strike Preferred Stock ("STRK Stock") offered hereby (the "STRK Sales Agreement Addendum"). In accordance with the terms of the Sales Agreement, as supplemented by the STRK Sales Agreement Addendum, under this prospectus supplement annex relating to the sale of our 8.00% Series A Perpetual Strike Preferred Stock (the "STRK Stock Annex"), we may offer and sell shares of our STRK Stock having an aggregate offering price of up to $2,100,000,000 from time to time through one or more of the Agents, acting as our sales agents. The shares of STRK Stock offered hereunder are among the securities described in the base prospectus supplement dated November 4, 2025 that we filed with the Securities and Exchange Commission (the "SEC") on such date, as supplemented by the supplement to the base prospectus supplement dated March 23, 2026 (as supplemented, the "base prospectus supplement") and a prospectus dated January 27, 2025. This STRK Stock Annex should be read in conjunction with that accompanying base prospectus supplement and prospectus and the contents of that accompanying base prospectus supplement and prospectus are incorporated by reference into this STRK Stock Annex.

We had previously registered the offer and sale of up to $20,340,632,356.64 of our STRK Stock under a prior prospectus supplement annex dated November 4, 2025, the accompanying base prospectus supplement and prospectus. Such prior offering of STRK Stock was terminated on March 22, 2026.

Our STRK Stock is listed on The Nasdaq Global Select Market under the trading symbol "STRK." On March 20, 2026, the last reported sale price of our STRK Stock as reported on The Nasdaq Global Select Market was $75.41 per share, and the last reported sale price of our class A common stock as reported on The Nasdaq Global Select Market was $135.66 per share.

STRK STOCK

The up to $2,100,000,000 of shares of STRK Stock that we may offer and sell under this STRK Stock Annex and the accompanying base prospectus supplement and prospectus constitutes a further issuance of shares of STRK Stock in addition to the 14,020,744 shares of STRK Stock outstanding as of the date of this STRK Stock Annex. Other than the issue date, the first regular dividend record date and the first regular dividend payment date, the STRK Stock that we may offer and sell under this STRK Stock Annex and the accompanying base prospectus supplement and prospectus will have terms identical to, will have the same CUSIP number as, and will vote together with, the STRK Stock outstanding as of the date of this STRK Stock Annex immediately upon issuance.

The liquidation preference of the STRK Stock is $100 as of the date of this STRK Stock Annex. On July 7, 2025, we filed a certificate of amendment (the "STRK Amendment") with the Secretary of State of the State of Delaware to the STRK Stock certificate of designations so that, together with other conforming changes, the STRK Stock has a liquidation preference that is initially $100 per share; provided, however, that, effective immediately after the close of business on each business day on or after July 7, 2025 (and, on or after July 7, 2025, if applicable, during the course of a business day on which any sale transaction to be settled by the issuance of STRK Stock is executed, from the exact time of the first such sale transaction during such business day until the close of business of such business day), the liquidation preference per share of STRK Stock will be adjusted to be the greatest of (i) the stated amount of $100 per share of STRK Stock (the "stated amount"); (ii) in the case of any business day on or after July 7, 2025 with respect to which we have, on such business day or any business day during the ten trading day period preceding such business day, executed any sale transaction to be settled by the issuance of STRK Stock, an amount equal to the "last reported sale price" (as defined in this STRK Stock Annex) per share of STRK Stock on the trading day immediately before such business day; and (iii) the arithmetic average of the last reported sale prices per share of STRK Stock for each trading day of the ten consecutive trading days immediately preceding such business day; provided that, for purposes of the definition of liquidation