SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 2)

INTEGRAL AD SCIENCE HOLDING CORP.

(Name of Issuer)

Common Stock, $0.001

(Title of Class of Securities)

45828L108

(CUSIP Number)

12/23/2025

(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 No.

45828L108

Names of Reporting Persons

Atlas Venture Fund VIII, L.P.

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 0.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 0.00

Aggregate Amount Beneficially Owned by Each Reporting Person

0.00

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)

0.0 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

CUSIP No.

45828L108

Names of Reporting Persons

Atlas Venture Associates VIII, L.P.

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 0.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 0.00

Aggregate Amount Beneficially Owned by Each Reporting Person

0.00

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)

0.0 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

CUSIP No.

45828L108

Names of Reporting Persons

Atlas Venture Associates VIII, Inc.

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 0.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 0.00

Aggregate Amount Beneficially Owned by Each Reporting Person

0.00

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)

0.0 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

Item 1.

(a)

Name of issuer:

INTEGRAL AD SCIENCE HOLDING CORP.

(b)

Address of issuer's principal executive offices:

12 East 49th Street, 20th Floor New York, NY, 10017

Item 2.

(a)

Name of person filing:

This Statement is being filed on behalf of Atlas Venture Fund VIII, L.P. ("Atlas VIII"), Atlas Venture Associates VIII, L.P. ("AVA VIII LP"), the sole general partner of Atlas VIII, and Atlas Venture Associates VIII, Inc. ("AVA VIII INC"), the sole general partner of AVA VIII LP.

(b)

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

The principal business address of each of Atlas VIII, AVA VIII LP, and AVA VIII INC is 56 Wareham Street, 3rd Flr, Boston, MA 02118.

(c)

Citizenship:

Each of Atlas VIII, AVA VIII LP and AVA VIII INC is organized under the laws of Delaware.

(d)

Title of class of securities:

Common Stock, $0.001

(e)

CUSIP No.:

45828L108

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:

As of December 23, 2025, none of the Reporting Persons may be deemed to beneficially own any shares of the Common Stock of the Issuer.

(b)

Percent of class:

0.0 %

(c)

Number of shares as to which the person has:

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

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

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

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

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.

Atlas Venture Fund VIII, L.P.

Signature:	/s/ Frank Castellucci
Name/Title:	General Counsel and Secretary of General Partner of General Partner
Date:	12/23/2025

Atlas Venture Associates VIII, L.P.

Signature:	/s/ Frank Castellucci
Name/Title:	General Counsel and Secretary of General Partner
Date:	12/23/2025

Atlas Venture Associates VIII, Inc.

Signature:	/s/ Frank Castellucci
Name/Title:	General Counsel and Secretary
Date:	12/23/2025

Amendment: SEC Form SCHEDULE 13G/A filed by Integral Ad Science Holding Corp.