X0508 4 2025-11-04 0 0001562088 Duolingo, Inc. DUOL 0001870272 Hacker Severin C/O DUOLINGO, INC. 5900 PENN AVENUE PITTSBURGH PA 15206 1 1 1 0 Chief Tech Officer, Co-Founder 1 Class A Common Stock 2025-11-04 4 C 0 10000 38.08 A 10072 D Class A Common Stock 2025-11-04 4 S 0 744 257.92 D 9328 D Class A Common Stock 2025-11-04 4 S 0 936 258.7742 D 8392 D Class A Common Stock 2025-11-04 4 S 0 560 259.708 D 7832 D Class A Common Stock 2025-11-04 4 S 0 165 261.1384 D 7667 D Class A Common Stock 2025-11-04 4 S 0 1778 261.944 D 5889 D Class A Common Stock 2025-11-04 4 S 0 560 262.9724 D 5329 D Class A Common Stock 2025-11-04 4 S 0 1625 264.0606 D 3704 D Class A Common Stock 2025-11-04 4 S 0 760 265.0164 D 2944 D Class A Common Stock 2025-11-04 4 S 0 1727 266.1228 D 1217 D Class A Common Stock 2025-11-04 4 S 0 1145 266.8679 D 72 D Stock Option (Right to Buy) 38.08 2025-11-04 4 M 0 10000 0 D 2030-12-02 Class B Common Stock 10000 15252 D Class B Common Stock 2025-11-04 4 C 0 10000 0 A Class A Common Stock 10000 124305 D Class B Common Stock 2025-11-04 4 C 0 10000 0 D Class A Common Stock 10000 114305 D Class B Common Stock Class A Common Stock 2886917 2886917 I See footnote The sale was effected pursuant to the Reporting Person's Rule 10b5-1 trading plan adopted on September 11, 2024. The price reported in Column 4 is a weighted average sale price calculated by the broker executing the sales. These shares were sold in multiple transactions at prices ranging from $257.23 to $258.20, inclusive. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. The price reported in Column 4 is a weighted average sale price calculated by the broker executing the sales. These shares were sold in multiple transactions at prices ranging from $258.23 to $259.22, inclusive. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. The price reported in Column 4 is a weighted average sale price calculated by the broker executing the sales. These shares were sold in multiple transactions at prices ranging from $259.29 to $260.05, inclusive. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. The price reported in Column 4 is a weighted average sale price calculated by the broker executing the sales. These shares were sold in multiple transactions at prices ranging from $260.46 to $261.44, inclusive. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. The price reported in Column 4 is a weighted average sale price calculated by the broker executing the sales. These shares were sold in multiple transactions at prices ranging from $261.49 to $262.35, inclusive. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. The price reported in Column 4 is a weighted average sale price calculated by the broker executing the sales. These shares were sold in multiple transactions at prices ranging from $262.49 to $263.42, inclusive. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. The price reported in Column 4 is a weighted average sale price calculated by the broker executing the sales. These shares were sold in multiple transactions at prices ranging from $263.50 to $264.44, inclusive. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. The price reported in Column 4 is a weighted average sale price calculated by the broker executing the sales. These shares were sold in multiple transactions at prices ranging from $264.50 to $265.49, inclusive. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. The price reported in Column 4 is a weighted average sale price calculated by the broker executing the sales. These shares were sold in multiple transactions at prices ranging from $265.51 to $266.50, inclusive. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. The price reported in Column 4 is a weighted average sale price calculated by the broker executing the sales. These shares were sold in multiple transactions at prices ranging from $266.51 to $267.38, inclusive. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. The shares subject to the option are fully vested and exercisable. Each share of Class B Common Stock is convertible at any time at the option of the Reporting Person into one share of Class A Common Stock and has no expiration date. Each share of Class B Common Stock will convert automatically into one share of Class A Common Stock in connection with: (i) any transfer, whether or not for value, except for certain permitted transfers further described in the Issuer's amended and restated certificate of incorporation, (ii) such time as the aggregate number of shares of Class B Common Stock outstanding ceases to represent 5% of the aggregate number of shares of Common Stock outstanding, and (iii) the death of the Reporting Person. Shares held by SBH Trust dated March 10, 2020, of which Reporting Person is Trustee. /s/ Stephen Chen, as Attorney-in-Fact for Severin Hacker 2025-11-06