SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 4)

RUBRIK, INC.

(Name of Issuer)

Class A Common Stock, $0.000025 par value

(Title of Class of Securities)

781154109

(CUSIP Number)

06/30/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13G

CUSIP Number(s):

781154109

Names of Reporting Persons

Lightspeed Venture Partners IX, L.P.

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 3,121,772.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 3,121,772.00

Aggregate Amount Beneficially Owned by Each Reporting Person

3,121,772.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

1.9 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

CUSIP Number(s):

781154109

Names of Reporting Persons

Lightspeed General Partner IX, L.P.

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 3,121,772.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 3,121,772.00

Aggregate Amount Beneficially Owned by Each Reporting Person

3,121,772.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

1.9 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

CUSIP Number(s):

781154109

Names of Reporting Persons

Lightspeed Ultimate General Partner IX, Ltd.

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 3,121,772.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 3,121,772.00

Aggregate Amount Beneficially Owned by Each Reporting Person

3,121,772.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

1.9 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

CUSIP Number(s):

781154109

Names of Reporting Persons

Lightspeed SPV I, LLC

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 1,410,445.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,410,445.00

Aggregate Amount Beneficially Owned by Each Reporting Person

1,410,445.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

0.9 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

CUSIP Number(s):

781154109

Names of Reporting Persons

Lightspeed SPV I-B, LLC

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 1,110,100.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,110,100.00

Aggregate Amount Beneficially Owned by Each Reporting Person

1,110,100.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

0.7 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

CUSIP Number(s):

781154109

Names of Reporting Persons

Lightspeed SPV I-C, LLC

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 777,013.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 777,013.00

Aggregate Amount Beneficially Owned by Each Reporting Person

777,013.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

0.5 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

CUSIP Number(s):

781154109

Names of Reporting Persons

LS SPV Management, LLC

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 3,297,558.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 3,297,558.00

Aggregate Amount Beneficially Owned by Each Reporting Person

3,297,558.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

2.0 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

CUSIP Number(s):

781154109

Names of Reporting Persons

Lightspeed Venture Partners Select II, L.P.

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 724,730.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 724,730.00

Aggregate Amount Beneficially Owned by Each Reporting Person

724,730.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

0.4 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

CUSIP Number(s):

781154109

Names of Reporting Persons

Lightspeed General Partner Select II, L.P.

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 724,730.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 724,730.00

Aggregate Amount Beneficially Owned by Each Reporting Person

724,730.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

0.4 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

CUSIP Number(s):

781154109

Names of Reporting Persons

Lightspeed Ultimate General Partner Select II, Ltd.

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 724,730.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 724,730.00

Aggregate Amount Beneficially Owned by Each Reporting Person

724,730.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

0.4 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

Item 1.

(a)

Name of issuer:

RUBRIK, INC.

(b)

Address of issuer's principal executive offices:

3495 Deer Creek Road, Palo Alto, CA, 94304.

Item 2.

(a)

Name of person filing:

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.

(b)

Address or principal business office or, if none, residence:

c/o Lightspeed Venture Partners 2200 Sand Hill Road Menlo Park, CA 94025

(c)

Citizenship:

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

(d)

Title of class of securities:

Class A Common Stock, $0.000025 par value

(e)

CUSIP No.:

781154109

Item 3.

If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

(a)

Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);

(b)

Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);

(c)

Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);

(d)

Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);

(e)

An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);

(f)

An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);

(g)

A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);

(h)

A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);

(i)

A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);

(j)

A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J),
please specify the type of institution:

(k)

Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).

Item 4.

Ownership

(a)

Amount beneficially owned:

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.

(b)

Percent of class:

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.

(c)

Number of shares as to which the person has:

(i) Sole power to vote or to direct the vote:

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.

(ii) Shared power to vote or to direct the vote:

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.

(iii) Sole power to dispose or to direct the disposition of:

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.

(iv) Shared power to dispose or to direct the disposition of:

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.

Item 5.

Ownership of 5 Percent or Less of a Class.

Ownership of 5 percent or less of a class

Item 6.

Ownership of more than 5 Percent on Behalf of Another Person.

Not Applicable

Item 7.

Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.

Not Applicable

Item 8.

Identification and Classification of Members of the Group.

Not Applicable

Item 9.

Notice of Dissolution of Group.

Not Applicable

Item 10.

Certifications:

Not Applicable

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Lightspeed Venture Partners IX, L.P.

Signature:	/s/ Ravi Mhatre
Name/Title:	See Note 1
Date:	08/14/2026

Lightspeed General Partner IX, L.P.

Signature:	/s/ Ravi Mhatre
Name/Title:	By Lightspeed Ultimate General Partner IX, Ltd., its General Partner, By Ravi Mhatre, Director
Date:	08/14/2026

Lightspeed Ultimate General Partner IX, Ltd.

Signature:	/s/ Ravi Mhatre
Name/Title:	By Ravi Mhatre, Director
Date:	08/14/2026

Lightspeed SPV I, LLC

Signature:	/s/ Ravi Mhatre
Name/Title:	By LS SPV Management, LLC, its Manager, By Ravi Mhatre, Managing Member
Date:	08/14/2026

Lightspeed SPV I-B, LLC

Signature:	/s/ Ravi Mhatre
Name/Title:	By LS SPV Management, LLC, its Manager, By Ravi Mhatre, Managing Member
Date:	08/14/2026

Lightspeed SPV I-C, LLC

Signature:	/s/ Ravi Mhatre
Name/Title:	By LS SPV Management, LLC, its Manager, By Ravi Mhatre, Managing Member
Date:	08/14/2026

LS SPV Management, LLC

Signature:	/s/ Ravi Mhatre
Name/Title:	By Ravi Mhatre, Managing Member
Date:	08/14/2026

Lightspeed Venture Partners Select II, L.P.

Signature:	/s/ Ravi Mhatre
Name/Title:	See Note 2
Date:	08/14/2026

Lightspeed General Partner Select II, L.P.

Signature:	/s/ Ravi Mhatre
Name/Title:	By Lightspeed Ultimate General Partner Select II, Ltd., its General Partner, By Ravi Mhatre, Director
Date:	08/14/2026

Lightspeed Ultimate General Partner Select II, Ltd.

Signature:	/s/ Ravi Mhatre
Name/Title:	By Ravi Mhatre, Director
Date:	08/14/2026

Comments accompanying signature: 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

Exhibit Information

Exhibit 99.1 Joint Filing Agreement