Q1 2026 HSR filings increased 14% over Q1 2025 HSR filings, with a steady overall increase in HSR filings in 2025

View full image: US monthly merger notifications 2023 – 2026*

Despite the rollercoaster of HSR Rule changes in 2025 and Q1 2026, there has been a notable surge in HSR filing activity in the past 15 months. Drawing on White & Case’s Global Antitrust Merger StatPak (WAMS), the first real-time clearinghouse for global merger notification data, we are also seeing elevated merger control activity globally that parallels this uptick in US HSR Filings. Q4 2025 was the strongest quarter for HSR Filings since Q4 2022, with a 12% increase over Q4 2024 HSR Filings and a 29% jump from Q4 2023's HSR Filings. The upward momentum through the end of 2025 contributed to a full-year total of 2,175 HSR Filings, surpassing 2024's already elevated total of 2,158 and exceeding 2023's 1,833 HSR Filings by 18%. While high, this HSR Filing activity does not approach the record 3,520 HSR Filings in 2021.

The 2025 deal-making momentum has carried into early 2026. January 2026 saw 180 HSR Filings, eclipsing the historical three-year (2023-2025) average for January HSR Filings by 7%. February 2026 continued the trend with 188 HSR Filings, not quite at the level of February 2025's rush to file before the New HSR Rules went into effect, but 8% above the historical three-year average for February HSR Filings.

Importantly, March 2026 HSR Filings reflected a massive jump of 128% over March 2025's 89 HSR Filings. This dramatic increase was expected, as parties avoided making HSR Filings immediately after the New HSR Rules went into effect. March 2026 had the eighth most HSR Filings of any month since January 2023.

Taken as a whole, Q1 2026 shows an increase of 14% over Q1 2025, signaling sustained deal-making activity. HSR Filings are expected to remain high throughout the first half of 2026, even amid economic and geopolitical uncertainty, driven by an active M&A environment, and an administration that seems eager to approve deals.

As of March 19, 2026, HSR Filings can now be made under the Old HSR Rules or the New HSR Rules while the U.S. Court of Appeals for the Fifth Circuit considers whether the New HSR Rules should remain vacated, so the lower filing burden may show an increase in HSR Filings in the near term. Looking ahead, we can also expect the Trump administration to continue its "friendly" approach to merger enforcement. In the past 12 months, the Trump administration has resumed the practice of approving mergers subject to structural remedies, a practice that fell out of favor during the Biden years. As shown below, in the first year of the Trump administration, the agencies have approved 11 mergers subject to a structural remedy, one subject to a behavioral remedy, and one subject to a mixed remedy.

View full image: Merger enforcement by the numbers: 2025 + Q1 2026

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