MARINER JONATHAN D 4

What Happened Jonathan D. Mariner, a director of OneStream, reported dispositions on April 1, 2026 related to the company’s merger. The filing shows five dispositions totaling 439,043 shares (7,130 shares of stock + 431,913 in derivative instruments). Under the merger agreement, these holdings were cancelled/converted into cash at the Per Share Price of $24.00, implying gross consideration of approximately $10,537,032 before applicable withholding taxes.

Key Details

• Transaction date: April 1, 2026; filing date: April 2, 2026 (timely).
• Total shares/derivatives disposed: 439,043 shares (7,130 direct shares; 206,949 + 40,051 + 50,000 + 134,913 derivative units).
• Price / consideration: $24.00 per share (Per Share Price under the Merger Agreement); gross value ≈ $10.54M before tax withholdings.
• Nature of transaction: Disposition to the issuer (D) — merger-related cancellations/conversions, not open-market sales.
• Derivative types: The derivatives converted include restricted stock units (RSUs), common units, and a stock option (per filing footnotes).
• Holdings after transaction: Not specified in the provided filing details.
• Tax/withholding: Cash paid is subject to applicable withholding taxes per footnotes.
• Footnotes: F1–F5 explain the Merger structure and that RSUs accelerated and were converted to cash, common units/options were cancelled and converted to cash (or de minimis cash for certain Class C shares), and one holding is held by the Jonathan D. Mariner Revocable Trust.

Context These were merger-related conversions (issuer dispositions) rather than voluntary open-market sales. RSUs were accelerated and cancelled for cash at the merger price; vested options were cashed out for the excess of the merger price over exercise price. Such filings reflect corporate transaction mechanics rather than a typical insider buy/sell signal; they do not by themselves indicate the director’s view of the company’s future.