Atlas Venture Fund VIII, L.P. - 23 Dec 2025 Form 4 Insider Report for INTEGRAL AD SCIENCE HOLDING CORP. (IAS)

Reporting relationship: 10%+ Owner
Issuer ticker: IAS
Reported as of: 23 Dec 2025
Net transaction value: -$234,044,531
SEC form: 4
Accepted by SEC: 23 Dec 2025, 20:35:54 UTC
Prior SEC filing: 29 Jun 2021
Source filing: View source filing
Reporting owner signature: Atlas Venture Fund VIII, L.P., By: Atlas Venture Associates VIII, L.P., its general partner, By: Atlas Venture Associates VIII, Inc., its general partner, By: Frank Castellucci, General Counsel and Secretary /s/ Frank...

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Atlas Venture Fund VIII, L.P., By: Atlas Venture Associates VIII, L.P., its general partner, By: Atlas Venture Associates VIII, Inc., its general partner, By: Frank Castellucci, General Counsel and Secretary /s/ Frank Castellucci

Key filing fact

Atlas Venture Fund VIII, L.P. filed Form 4 for INTEGRAL AD SCIENCE HOLDING CORP. (IAS) on 23 Dec 2025.

Key facts

This page summarizes Atlas Venture Fund VIII, L.P.'s Form 4 filing for INTEGRAL AD SCIENCE HOLDING CORP. (IAS).
1 reported transaction and 0 derivative rows are listed below.
Accepted by SEC: 23 Dec 2025, 20:35.

Change

Previous filing in this sequence was filed on 29 Jun 2021.
Current net transaction value: -$234,044,531.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (3)

CIK 0001451626 Primary reporting owner

Atlas Venture Fund VIII, L.P.

Relationship: 10%+ Owner
Address: 56 WAREHAM STREET, FLOOR 3, BOSTON
Signature: Atlas Venture Fund VIII, L.P., By: Atlas Venture Associates VIII, L.P., its general partner, By: Atlas Venture Associates VIII, Inc., its general partner, By: Frank Castellucci, General Counsel and Secretary /s/ Frank Castellucci
Signature date: 23 Dec 2025

CIK 0001451625

Atlas Venture Associates VIII, L.P.

Relationship: 10%+ Owner
Address: 56 WAREHAM STREET, FLOOR 3, BOSTON
Signature: Atlas Venture Associates VIII, L.P. By: Atlas Venture Associates VIII, Inc., its general partner, By: Frank Castellucci, General Counsel and Secretary /s/ Frank Castellucci
Signature date: 23 Dec 2025

CIK 0001451624

Atlas Venture Associates VIII, Inc.

Relationship: 10%+ Owner
Address: 56 WAREHAM STREET, FLOOR 3, BOSTON
Signature: Atlas Venture Associates VIII, Inc, By: Frank Castellucci, General Counsel and Secretary /s/ Frank Castellucci
Signature date: 23 Dec 2025

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

IAS transaction

Common stock, $0.001 par value

Other

Transaction value: $234,044,531
Shares: -22,722,770
Change %: -100%
Price: $10.30
Shares after: 0
Date: 23 Dec 2025
Ownership: See Footnote
Footnotes: F1, F2

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Section 16 status

Atlas Venture Fund VIII, L.P. is no longer subject to Section 16 filing requirements. Form 4 or Form 5 obligations may still apply in specific circumstances.

Explanation of responses 2 footnotes

Footnote F1

This Form 4 reports securities disposed pursuant to the Agreement and Plan of Merger, dated as of September 24, 2025 (the "Merger Agreement") by and among the Issuer, Igloo Group Parent, Inc., a Delaware corporation ("Parent"), and Igloo Group Acquisition Company, Inc., a Delaware corporation and a wholly owned subsidiary of Parent ("Merger Sub"). Pursuant to the Merger Agreement, on December 23, 2025 (the "Effective Time"), Merger Sub merged with and into the Issuer, with the Issuer surviving as a wholly owned subsidiary of Parent. At the Effective Time, each share of common stock of the Issuer owned by the reporting persons immediately prior to the Effective Time was automatically cancelled, extinguished and converted into the right to receive $10.30 in cash, without interest thereon.

Footnote F2

Shares held directly by Atlas Venture Fund VIII, L.P. ("Atlas VIII"). Atlas Venture Associates VIII, L.P. ("AVA VIII LP") is the sole general partner of Atlas VIII. Atlas Venture Associates VIII, Inc. ("AVA VIII Inc.") is the sole general partner of AVA VIII LP. Each of Atlas VIII, AVA VIII LP and AVA VIII Inc. disclaim beneficial ownership of all shares except to the extent of its pecuniary interest, if any, therein. This report shall not be deemed to be an admission that the reporting persons are the beneficial owners of such securities for purposes of Section 16 or for any other purpose.