| 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);
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| (b) | Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
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| (c) | Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
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| (d) | Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
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| (e) | An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
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| (f) | An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
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| (g) | A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
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| (h) | A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
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| (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);
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| (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:
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| (k) | Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
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| | |
| 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 %
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| (c) | Number of shares as to which the person has:
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| | (i) Sole power to vote or to direct the vote:
0
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| | (ii) Shared power to vote or to direct the vote:
0
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| | (iii) Sole power to dispose or to direct the disposition of:
0
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| | (iv) Shared power to dispose or to direct the disposition of:
0
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| Item 5. | Ownership of 5 Percent or Less of a Class. |
| | 
Ownership of 5 percent or less of a class
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| Item 6. | Ownership of more than 5 Percent on Behalf of Another Person. |
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Not Applicable
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| Item 7. | Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person. |
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Not Applicable
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| Item 8. | Identification and Classification of Members of the Group. |
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Not Applicable
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| Item 9. | Notice of Dissolution of Group. |
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Not Applicable
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