X0202 SCHEDULE 13G/A 0001020066-21-000003 0001020066 XXXXXXXX LIVE 6 Common Stock, par value $0.001 per share 03/31/2026 0001388658 iRhythm Holdings, Inc. 450056106 699 8TH STREET 699 8TH STREET San Francisco CA 94103 Rule 13d-1(b) SANDS CAPITAL MANAGEMENT, LLC b DE 0.00 0.00 0.00 0.00 0.00 0.0 IA The percentages reported in this Schedule 13G are based upon 32,862,408 Shares outstanding as of April 23, 2026 (according to the Issuer's Form 10-Q as filed with the Securities and Exchange Commission on April 30, 2026). SANDS FRANK M. b X1 0.00 0.00 0.00 0.00 0.00 0.0 HC IN The percentages reported in this Schedule 13G are based upon 32,862,408 Shares outstanding as of April 23, 2026 (according to the Issuer's Form 10-Q as filed with the Securities and Exchange Commission on April 30, 2026). iRhythm Holdings, Inc. 699 8TH STREET, 699 8TH STREET, San Francisco, CALIFORNIA, 94103. This Schedule 13G is being filed jointly by Sands Capital Management, LLC ("SCM") and Frank M. Sands ("Sands"). Sands holds ultimate voting and investment power over securities held by SCM. The principal business address of each of SCM and Sands is 1000 Wilson Blvd., Suite 3000, Arlington, VA 22209. SCM is organized under the laws of the State of Delaware. Sands is a citizen of the United States. N IA HC See rows 5 through 11 of cover pages. See rows 5 through 11 of cover pages. See rows 5 through 11 of cover pages. See rows 5 through 11 of cover pages. See rows 5 through 11 of cover pages. See rows 5 through 11 of cover pages. Y N Securities reported on this Schedule 13G are held in the accounts of various clients of SCM, which may include pension plans, endowments, foundations, mutual funds, charities, state and municipal government entities, Taft-Hartley plans, families, and individuals, among other types. Such clients have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the securities reported herein. No such client's interest in the class of securities reported herein is more than 5%. N SCM is reporting hereunder as an investment adviser pursuant to Item 3(e) above. Sands is reporting hereunder as a control person pursuant to Item 3(g) above. Y Y N By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11. SANDS CAPITAL MANAGEMENT, LLC /s/ Alexandra R. Fulk 05/08/2026 SANDS FRANK M. /s/ Frank M. Sands 05/08/2026