Duolingo, Inc.

(a) None.

(b)

(c) Trading Plans

During the three months ended June 30, 2026, certain of our directors and officers adopted or terminated a “Rule 10b5-1 trading arrangement” or “non-Rule 10b5-1 trading arrangement,” as each term is defined in Item 408(a) of Regulation S-K as follows:

On June 9, 2026, William "Bing" Gordon, amember of our Board of Directors, modified his Rule 10b5-1 sales plan that was originally adopted on December 11, 2025. The modified trading arrangement is intended to satisfy the affirmative defense of Rule 10b5-1(c) under the Exchange Act and provides for the sale of up to 40,000 shares of the Company’s Class A common stock. The trading arrangement will remain in effect until the earlier of (i)June 30, 2027, (ii) the completion of all authorized transactions, or (iii) termination in accordance with its terms.

On June 2, 2026, Dr. Luis von Ahn, Chief Executive Officer and member of the Company’s Board of Directors, and the Luis von Ahn Foundation, entered into a 10b5-1 sales plan (the “von Ahn 10b5-1 Sales Plan”) intended to satisfy the affirmative defense of Rule 10b5-1(c) under the Exchange Act, pursuant to which a maximum aggregate amount of up to 626,000 shares of the Company’s Class A common stock may be sold, consisting of (i) up to 226,000 shares issuable upon the exercise of vested stock options held by Dr. von Ahn and (ii) up to 400,000 shares held by Dr. von Ahn. Additionally, under the von Ahn 10b5-1 Sales Plan, up to 54,000 shares held by the Luis von Ahn Foundation) may be sold. The von Ahn 10b5-1 Sales Plan will remain in effect until the earlier of (1)September 15, 2027, (2) the date on which all trades set forth in the von Ahn 10b5-1 Sales Plan have been executed, or (3) such time as the von Ahn 10b5-1 Sales Plan is otherwise terminated or expires according to its terms.

On June 14, 2026, Stephen Chen, General Counsel, entered into a 10b5-1 sales plan (the “Chen 10b5-1 Sales Plan”) intended to satisfy the affirmative defense of Rule 10b5-1(c) of the Exchange Act and providing for (i) the sale of the net number of shares of Class A common stock underlying 12,524 unvested restricted stock units received after giving effect to the number of shares automatically sold to satisfy tax withholding obligations on each applicable vesting date (such total number of shares covered under clause (i) is not determinable) and (ii) the sale of 12,696 shares of Class A common stock. The Chen 10b5-1 Sales Plan will remain in effect until the earlier of (1)August 14, 2027, (2) the date on which all trades set forth in the Chen 10b5-1 Sales Plan have been executed, or (3) such time as the Chen 10b5-1 Sales Plan is otherwise terminated according to its terms.

No other “officer” (as defined in Rule 16a-1(f) under the Exchange Act) or director of the Company adopted, modified orterminated “Rule 10b5-1 trading arrangements” and/or “non-Rule 10b5-1 trading arrangements” (each as defined in Item 408 of Regulation S-K) during the three months ended June 30, 2026.