Director — Sallie Krawcheck: The filing discloses the appointment of a new independent director to the board, which is a governance matter rather than a senior executive management change.

of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Results of Operations and Financial Condition On February 26, 2026, the Company issued the Original Shareholder Letter. A copy of the Original Shareholder Letter, as corrected, is attached hereto as Exhibit 99.1 and incorporated herein by reference.

Other Events Duolingo’s Board of Directors has authorized a share repurchase program of up to $400 million. The program reflects the Company’s commitment to capital allocation, including returning capital to stockholders and managing dilution, while maintaining flexibility to invest in long-term growth. Repurchases under the program may be made from time to time in the open market, through privately negotiated transactions or otherwise. The actual timing, number and value of shares repurchase…

of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

CFO — Matthew Skaruppa: The CFO resigned with a named external successor appointed simultaneously and a transition agreement in place, indicating an orderly succession rather than a sudden loss of leadership.

Results of Operations and Financial Condition On January 12, 2026, Duolingo, Inc. (the “Company”) issued a press release announcing a preliminary update on certain operating metrics for the three months ended December 31, 2025. These preliminary results are based on the Company’s current estimate of its results for the quarter ended December 31, 2025, and remain subject to change based on the completion of closing and review procedures and the execution of the Company’s internal controls over…

of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Director — Bonnie Ross: The filing discloses the appointment of a new director to an expanded board, which is a routine governance event and not a departure of an existing executive.

of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Director — Mario Schlosser: The filing discloses the appointment of a new director to fill a vacancy, which is a routine board composition change rather than the departure of a senior executive.

Results of Operations and Financial Condition On May 8, 2024, Duolingo, Inc. (the “Company”) issued a press release announcing the financial results of the Company for the three months ended March 31, 2024 (the “Earnings Release”) and furnished with the Original 8-K as Exhibit 99.2 thereto (the “Original 8-K Exhibit”) a Shareholder Letter, dated May 8, 2024 (the “Original Shareholder Letter”). The Original Shareholder Letter was also posted to the Company’s website at investors.duolingo.com.…

of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Director — Laela Sturdy: A director resigned from the board and committees, but the filing explicitly states there was no disagreement with the company, indicating an orderly departure rather than a negative shock.

by reference. SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. DUOLINGO, INC. Date: March 5, 2024 By: /s/ Matthew Skaruppa Matthew Skaruppa Chief Financial Officer (Principal Financial Officer and Principal Accounting Officer)

Entry into a Material Definitive Agreement As previously disclosed, on November 16, 2021, Duolingo, Inc. (the “Company”) entered into an Office Lease Agreement (the “Lease”) with 5704 Penn Office, LLC. (the "Landlord"), to lease approximately 38,000 square feet of office space located at Liberty East at 141 South Saint Clair Street, Pittsburgh, Pennsylvania (the “Premises”) for additional office space. Initial base rent under the Lease was approximately $148,000 per month, with an increase by…