Thomas Anthony Shea - 01 Apr 2026 Form 4/A - Amendment Insider Report for OneStream, Inc. (OS)

Reporting relationship: CEO, Director, 10%+ Owner
Issuer ticker: OS
Reported as of: 01 Apr 2026
Net transaction value: $0
SEC form: 4/A - Amendment
Accepted by SEC: 03 Apr 2026, 19:28:59 UTC
Original report date: 02 Apr 2026
Prior SEC filing: 26 Mar 2026
Source filing: View source filing
Reporting owner signature: /s/ Holly Koczot, attorney-in-fact

Key filing fact

Thomas Anthony Shea filed Form 4/A - Amendment for OneStream, Inc. (OS) on 03 Apr 2026.

Key facts

This page summarizes Thomas Anthony Shea's Form 4/A - Amendment filing for OneStream, Inc. (OS).
13 reported transactions and 11 derivative rows are listed below.
Accepted by SEC: 03 Apr 2026, 19:28.

Change

Previous filing in this sequence was filed on 26 Mar 2026.
Current net transaction value: $0.

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/A - Amendment disclosures.

View source filing

Reporting Owners (1)

CIK 0002027929 Primary reporting owner

Shea Thomas Anthony

Relationship: CEO, Director, 10%+ Owner
Address: C/O ONESTREAM, INC., 191 N. CHESTER STREET, BIRMINGHAM
Signature: /s/ Holly Koczot, attorney-in-fact
Signature date: 03 Apr 2026

Reported non-derivative transactions

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

OS transaction

Class A Common Stock

Disposed to Issuer

Transaction value
Shares: -80,023
Change %: -100%
Price
Shares after: 0
Date: 01 Apr 2026
Ownership: Direct
Footnotes: F1, F2

OS transaction

Class A Common Stock

Disposed to Issuer

Transaction value
Shares: -379,963
Change %: -100%
Price
Shares after: 0
Date: 01 Apr 2026
Ownership: Direct
Footnotes: F1, F3

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

OS transaction Derivative

Common Units

Disposed to Issuer

Transaction value
Shares: -325,232
Change %: -100%
Price
Shares after: 0
Date: 01 Apr 2026
Ownership: See footnote
Underlying class: Class D Common Stock
Underlying amount: 325,232
Exercise price
Footnotes: F1, F4, F5

OS transaction Derivative

Class D Common Stock

Disposed to Issuer

Transaction value
Shares: -4,313,836
Change %: -100%
Price
Shares after: 0
Date: 01 Apr 2026
Ownership: Direct
Underlying class: Class A Common Stock
Underlying amount: 4,313,836
Exercise price
Footnotes: F1, F6

OS transaction Derivative

Class D Common Stock

Disposed to Issuer

Transaction value
Shares: -2,814,351
Change %: -100%
Price
Shares after: 0
Date: 01 Apr 2026
Ownership: See footnote
Underlying class: Class A Common Stock
Underlying amount: 2,814,351
Exercise price
Footnotes: F1, F6, F7

OS transaction Derivative

Class D Common Stock

Disposed to Issuer

Transaction value
Shares: -9,041,667
Change %: -100%
Price
Shares after: 0
Date: 01 Apr 2026
Ownership: See footnote
Underlying class: Class A Common Stock
Underlying amount: 9,041,667
Exercise price
Footnotes: F1, F7, F8

OS transaction Derivative

Stock Option (right to buy)

Disposed to Issuer

Transaction value
Shares: -619,835
Change %: -100%
Price
Shares after: 0
Date: 01 Apr 2026
Ownership: Direct
Underlying class: Class A Common Stock
Underlying amount: 619,835
Exercise price: $10.65
Footnotes: F1, F9

OS transaction Derivative

Stock Option (right to buy)

Disposed to Issuer

Transaction value
Shares: -504,472
Change %: -100%
Price
Shares after: 0
Date: 01 Apr 2026
Ownership: Direct
Underlying class: Class A Common Stock
Underlying amount: 504,472
Exercise price: $10.65
Footnotes: F1, F9

OS transaction Derivative

Stock Option (right to buy)

Disposed to Issuer

Transaction value
Shares: -149,979
Change %: -100%
Price
Shares after: 0
Date: 01 Apr 2026
Ownership: Direct
Underlying class: Class A Common Stock
Underlying amount: 149,979
Exercise price: $10.65
Footnotes: F1, F10

OS transaction Derivative

Stock Option (right to buy)

Disposed to Issuer

Transaction value
Shares: -473,008
Change %: -100%
Price
Shares after: 0
Date: 01 Apr 2026
Ownership: Direct
Underlying class: Class A Common Stock
Underlying amount: 473,008
Exercise price: $14.51
Footnotes: F1, F9

OS transaction Derivative

Stock Option (right to buy)

Disposed to Issuer

Transaction value
Shares: -435,161
Change %: -100%
Price
Shares after: 0
Date: 01 Apr 2026
Ownership: Direct
Underlying class: Class A Common Stock
Underlying amount: 435,161
Exercise price: $14.51
Footnotes: F1, F10

OS transaction Derivative

Stock Option (right to buy)

Disposed to Issuer

Transaction value
Shares: -55,795
Change %: -100%
Price
Shares after: 0
Date: 01 Apr 2026
Ownership: Direct
Underlying class: Class A Common Stock
Underlying amount: 55,795
Exercise price: $20.00
Footnotes: F1, F9

OS transaction Derivative

Stock Option (right to buy)

Disposed to Issuer

Transaction value
Shares: -92,992
Change %: -100%
Price
Shares after: 0
Date: 01 Apr 2026
Ownership: Direct
Underlying class: Class A Common Stock
Underlying amount: 92,992
Exercise price: $20.00
Footnotes: F1, F10

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

Additional SEC filing notes

Filing notes and footnotes

Section 16 status

Thomas Anthony Shea is no longer subject to Section 16 filing requirements. Form 4 or Form 5 obligations may still apply in specific circumstances.

Explanation of responses 10 footnotes

Footnote F1

Pursuant to the Agreement and Plan of Merger (the "Merger Agreement"), dated January 6, 2026, by and among OneStream, Inc. ("Issuer"), OneStream Software LLC, a subsidiary of Issuer ("Company LLC"), Onward AcquireCo Inc. ("Parent"), Onward Merger Sub 2, LLC ( "Merger Sub I") and Onward Merger Sub, Inc. ("Merger Sub II"), on April 1, 2026, Merger Sub 1 merged with and into Company LLC (the "First Merger"), with Company LLC surviving the First Merger and becoming a subsidiary of Parent, and Merger Sub II merged with and into Issuer (the "Second Merger" and together with the First Merger, the "Mergers"), with Issuer surviving the Second Merger and becoming a subsidiary of Parent.

Footnote F2

Pursuant to the Merger Agreement, at the effective time of the Mergers (the "Effective Time"), each share of Issuer Class A Common Stock was cancelled and converted into the right to receive $24.00 per share in cash (the "Per Share Price") without interest, less applicable withholding taxes.

Footnote F3

Represents an equal number of restricted stock units ("RSUs"). At the Effective Time, each unvested RSU award was cancelled and converted into the contingent right to receive a cash award, without interest, equal to the product of (a) the Per Share Price multiplied by (b) the total number of shares of Issuer's Class A Common Stock covered by such RSU award, less applicable withholding taxes. The vesting terms and conditions applicable to the unvested RSU awards as of immediately prior to the Mergers will remain in effect following the Mergers, provided that the vesting and payment of these cash awards to the extent not yet paid will accelerate and be paid upon the earlier of March 15, 2027 or a termination or resignation of the Reporting Person's employment with the Issuer, as a privately held entity, following the Mergers for any reason other than for cause.

Footnote F4

At the Effective Time, each Common Unit was cancelled and converted into the right to receive an amount in cash, without interest, equal to the Per Share Price, less applicable withholding taxes. Each corresponding share of Class C Common Stock was cancelled and converted into the right to receive $0.0001 in cash, without interest, less applicable withholding taxes.

Footnote F5

Shares held of record by the TSICU Corp. TSICU Corp. is a subchapter S corporation controlled by the Reporting Person, who has sole voting and dispositive power over the shares held by it.

Footnote F6

Pursuant to the Merger Agreement, at the Effective Time, each share of Class D Common Stock was cancelled and converted into the right to receive the Per Share Price, without interest, less applicable withholding taxes.

Footnote F7

Shares held of record by the Shea Family Trust dated December 25, 2019 (the "2019 Shea Family Trust"). The Reporting Person's spouse serves as the co-trustee for the 2019 Shea Family Trust. By virtue of his relationship, the Reporting Person may be deemed to share voting and dispositive power with respect to the shares held by the 2019 Shea Family Trust.

Footnote F8

At the Effective Time, the shares of Class D Common Stock were reinvested into Issuer, as a privately held entity following the Mergers, and were exchanged for equity interests in an entity that controls Parent.

Footnote F9

At the Effective Time, each vested option was cancelled and converted into the right to receive an amount in cash, without interest, equal to the product of (a) the total number of shares of Class A Common Stock subject to the option multiplied by (b) the excess, if any, of the Per Share Price over the exercise price per share of the option, less applicable withholding taxes.

Footnote F10

At the Effective Time, each unvested option was cancelled and converted into the contingent right to receive a cash award, without interest, equal to the product of (a) the total number of shares of Class A Common Stock subject to the option multiplied by (b) the excess, if any, of the Per Share Price over the exercise price per share of such option, less applicable withholding taxes. The vesting terms and conditions applicable to the unvested option as of immediately prior to the Mergers will remain in effect following the Mergers, provided that the vesting and payment of these cash awards to the extent not yet paid will accelerate and be paid upon the earlier of March 15, 2027 or a termination or resignation of the Reporting Person's employment with the Issuer, as a privately held entity, following the Mergers for any reason other than for cause.

SEC remarks

This amendment to the Reporting Person's Form 4 filed on April 2, 2026 is being filed solely to update footnotes 3 and 10 to clarify the vesting and payment terms following the Mergers of the cash awards applicable to the unvested RSU and stock option awards held by the Reporting Persons.