System1, Inc. Posts Supplemental Financials for Quarter Ended Dec 31, 2025

What Happened

• On March 11, 2026, System1, Inc. (SST) announced under Item 7.01 (Regulation FD Disclosure) that it posted supplemental financial information for the quarter ended December 31, 2025 on its investor relations website (https://ir.system1.com). The supplemental information is furnished as Exhibit 99.1 to the Form 8-K.

Key Details

• Filing date: March 11, 2026 (Form 8-K, Item 7.01 and Item 9.01).
• Period covered: quarter ended December 31, 2025.
• Material provided: supplemental financial information posted to the company’s investor website and furnished as Exhibit 99.1.
• Company note: the website content is not incorporated by reference into the Form 8-K.

Why It Matters

• Investors can review the supplemental quarterly financial material (metrics, schedules or reconciliations often included in supplements) to better understand System1’s recent quarterly results and trends. Because the material was furnished under Regulation FD (not filed), it was disclosed for public access but has a different legal status than formally filed reports. Checking the posted Exhibit 99.1 on the investor site provides the primary source for the details referenced in this filing.