The Hart-Scott-Rodino Antitrust Improvements Act of 1976 (HSR) is the U.S. law that requires parties to notify the antitrust agencies before closing a transaction above certain size thresholds, and then to wait a statutory period so the government can screen the deal for competitive harm. HSR is the procedural backbone of U.S. merger control — it gives regulators a look at deals before they close, when relief is still feasible.
How it works
For a reportable deal, both buyer and seller file a Notification and Report Form with both the Federal Trade Commission (FTC) and the DOJ Antitrust Division, pay a filing fee, and then observe an initial waiting period — 30 days (15 days for all-cash tender offers and certain bankruptcy sales). During the wait, one agency takes the review (see clearance). The agency can then:
- Let the period expire (or grant early termination) — the deal is cleared to close; or
- Issue a Second Request — a demand for much more information that extends the review by months.
The size thresholds
HSR reportability turns on two main tests, and the dollar figures are indexed annually for inflation:
- Size-of-transaction test — the deal value must exceed a threshold (in the mid-2020s, roughly $120M+, rising each year). Very large deals (a higher threshold) are reportable regardless of the parties' size.
- Size-of-person test — for deals between the two thresholds, one party must be above a larger size and the other above a smaller size (measured by assets or annual net sales).
Because the numbers reset every year, practitioners always check the current thresholds. Many deals — including most lower-middle-market transactions — fall below the thresholds and are not HSR-reportable, though they remain subject to the antitrust laws generally.
"Gun-jumping"
HSR enforces a strict separation between signing and closing: the parties must remain independent until the waiting period expires. "Gun-jumping" — the buyer prematurely exercising control over, or coordinating with, the target before clearance — is itself an HSR (and Sherman Act) violation carrying substantial daily civil penalties. So even after signing, the parties operate at arm's length until cleared, which is why closing checklists track HSR clearance as a condition precedent.
Why it matters to deal timing
For any HSR-reportable deal, the waiting period is a gating item on the path to close. A clean deal clears in 30 days; a deal raising competitive concerns can be pulled into a Second Request and stretch six months to a year or more, fundamentally affecting the timetable, financing and risk allocation (which is why agreements address antitrust risk through "hell-or-high-water" covenants, conditions and reverse break fees). The HSR form itself was substantially expanded in 2025, increasing the information burden of filing.
See also
- Antitrust and merger control — Government review of mergers to prevent harm to competition.
- FTC merger review — Competition review of a transaction by the U.S. Federal Trade Commission, sharing jurisdiction with the DOJ Antitrust Division for HSR-reportable deals.
- DOJ Antitrust Division review — Competition review by the U.S. Department of Justice Antitrust Division. Allocation between DOJ and FTC depends on the industries involved.
- Second Request — An extended antitrust investigation under HSR in which the reviewing agency demands additional information after the initial 30-day waiting period, lengthening review by months.
- Closing checklist — An exhaustive list of conditions, deliverables, signatures, consents and filings required to take a deal from signed agreement to closed transaction. Maintained by deal counsel.