X0202 SCHEDULE 13G/A 0001104659-24-119273 0001539061 XXXXXXXX LIVE 4 Class A Common Stock, $0.000025 par value 06/30/2026 0001943896 RUBRIK, INC. 781154109 3495 Deer Creek Road Palo Alto CA 94304 Rule 13d-1(d) Lightspeed Venture Partners IX, L.P. b E9 0.00 3121772.00 0.00 3121772.00 3121772.00 1.9 PN Lightspeed General Partner IX, L.P. b E9 0.00 3121772.00 0.00 3121772.00 3121772.00 1.9 PN Lightspeed Ultimate General Partner IX, Ltd. b E9 0.00 3121772.00 0.00 3121772.00 3121772.00 1.9 OO Lightspeed SPV I, LLC b DE 0.00 1410445.00 0.00 1410445.00 1410445.00 0.9 OO Lightspeed SPV I-B, LLC b DE 0.00 1110100.00 0.00 1110100.00 1110100.00 0.7 OO Lightspeed SPV I-C, LLC b DE 0.00 777013.00 0.00 777013.00 777013.00 0.5 OO LS SPV Management, LLC b DE 0.00 3297558.00 0.00 3297558.00 3297558.00 2.0 OO Lightspeed Venture Partners Select II, L.P. b E9 0.00 724730.00 0.00 724730.00 724730.00 0.4 PN Lightspeed General Partner Select II, L.P. b E9 0.00 724730.00 0.00 724730.00 724730.00 0.4 PN Lightspeed Ultimate General Partner Select II, Ltd. b E9 0.00 724730.00 0.00 724730.00 724730.00 0.4 OO RUBRIK, INC. 3495 Deer Creek Road, Palo Alto, CA, 94304. The names of the persons filing this report (collectively, the "Reporting Persons") are: Lightspeed Venture Partners IX, L.P. ("Lightspeed IX") Lightspeed General Partner IX, L.P. ("LGP IX") Lightspeed Ultimate General Partner IX, Ltd. ("LUGP IX") Lightspeed SPV I, LLC ("Lightspeed SPV I") Lightspeed SPV I-B, LLC ("Lightspeed SPV I-B") Lightspeed SPV I-C, LLC ("Lightspeed SPV I-C") LS SPV Management, LLC ("LS SPV") Lightspeed Venture Partners Select II, L.P. ("Lightspeed Select II") Lightspeed General Partner Select II, L.P. ("LGP Select II") Lightspeed Ultimate General Partner Select II, Ltd. ("LUGP Select II") The Reporting Persons expressly disclaim status as a "group" for purposes of this Schedule 13G/A. c/o Lightspeed Venture Partners 2200 Sand Hill Road Menlo Park, CA 94025 Lightspeed IX Cayman Islands LGP IX Cayman Islands LUGP IX Cayman Islands Lightspeed SPV I Delaware Lightspeed SPV I-B Delaware Lightspeed SPV I-C Delaware LS SPV Delaware Lightspeed Select II Cayman Islands LGP Select II Cayman Islands LUGP Select II Cayman Islands Y Row 9 of each Reporting Person's cover page to this Schedule 13G/A sets forth the aggregate number of shares of Class A common stock of the Issuer beneficially owned by such Reporting Person as of June 30, 2026 and is incorporated by reference. The Reporting Persons' ownership of the Issuer's securities consists of (i) 3,121,772 shares of Class B common stock directly held by Lightspeed IX; (ii) 1,410,445 shares of Class B common stock directly held by Lightspeed SPV I; (iii) 1,110,100 shares of Class B common stock directly held by Lightspeed SPV I-B; (iv) 777,013 shares of Class B common stock directly held by Lightspeed SPV I-C; and (v) 724,730 shares of Class B common stock directly held by Lightspeed Select II. Collectively, the Reporting Persons beneficially own an aggregate of 7,144,060 shares of Class B common stock. LUGP IX serves as the sole general partner of LGP IX, which serves as the sole general partner of Lightspeed IX. LS SPV serves as the manager of each of Lightspeed SPV I, Lightspeed SPV I-B and Lightspeed SPV I-C. LUGP Select II serves as the sole general partner of LGP Select II, which serves as the sole general partner of Lightspeed Select II. Row 11 of each Reporting Person's cover page to this Schedule 13G/A sets forth the percentages of the shares of Class A common stock of the Issuer beneficially owned by such Reporting Person as of June 30, 2026 and is incorporated by reference. Collectively, the Reporting Persons beneficially own 3.5% of the common stock and 4.2% of the Class A common stock. The foregoing percentages are based upon a total of 208,209,919 shares of common stock (163,338,116 shares of Class A common stock and 44,871,803 shares of Class B common stock) outstanding as of May 31, 2026, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission (the "SEC") on June 5, 2026. With respect to the percentage of Class A common stock, the shares outstanding, in each case, has been adjusted in accordance with rules of the SEC, to reflect the issuance of 2,381,353 shares of Class A common stock subsequent to May 31, 2026 upon conversion of shares of Class B common stock by the Reporting Persons and to give effect to the full conversion of Class B common stock beneficially owned by such Reporting Person. Row 5 of each Reporting Person's cover page to this Schedule 13G/A sets forth the sole power to vote or to direct the vote of securities of the Issuer beneficially owned by such Reporting Person as of June 30, 2026 and is incorporated by reference. Row 6 of each Reporting Person's cover page to this Schedule 13G/A sets forth the shared power to vote or to direct the vote of securities of the Issuer beneficially owned by such Reporting Person as of June 30, 2026 and is incorporated by reference. Row 7 of each Reporting Person's cover page to this Schedule 13G/A sets forth the sole power to dispose or to direct the disposition of securities of the Issuer beneficially owned by such Reporting Person as of June 30, 2026 and is incorporated by reference. Row 8 of each Reporting Person's cover page to this Schedule 13G/A sets forth the shared power to dispose or to direct the disposition of securities of the Issuer beneficially owned by such Reporting Person as of June 30, 2026 and is incorporated by reference. N Y Y Y Y Y Y Exhibit 99.1 Joint Filing Agreement Lightspeed Venture Partners IX, L.P. /s/ Ravi Mhatre 08/14/2026 Lightspeed General Partner IX, L.P. /s/ Ravi Mhatre 08/14/2026 Lightspeed Ultimate General Partner IX, Ltd. /s/ Ravi Mhatre 08/14/2026 Lightspeed SPV I, LLC /s/ Ravi Mhatre 08/14/2026 Lightspeed SPV I-B, LLC /s/ Ravi Mhatre 08/14/2026 Lightspeed SPV I-C, LLC /s/ Ravi Mhatre 08/14/2026 LS SPV Management, LLC /s/ Ravi Mhatre 08/14/2026 Lightspeed Venture Partners Select II, L.P. /s/ Ravi Mhatre 08/14/2026 Lightspeed General Partner Select II, L.P. /s/ Ravi Mhatre 08/14/2026 Lightspeed Ultimate General Partner Select II, Ltd. /s/ Ravi Mhatre 08/14/2026 Note 1: By Lightspeed General Partner IX, L.P., its General Partner, By Lightspeed Ultimate General Partner IX, Ltd., its General Partner, By Ravi Mhatre, Director Note 2: By Lightspeed General Partner Select II, L.P., its General Partner, By Lightspeed Ultimate General Partner Select II, Ltd., its General Partner, By Ravi Mhatre, Director