When Does My Startup’s Acquisition Require an HSR Antitrust Filing?
You got the term sheet. The acquirer is serious. Then your counsel mentions an HSR filing and a 30-day waiting period. Do you actually need that? And what happens if you skip it?
The Hart-Scott-Rodino (HSR) Act requires parties to certain mergers and acquisitions to notify the Federal Trade Commission (FTC) and Department of Justice (DOJ) before closing. The filing triggers a mandatory waiting period. The deal cannot close until the government clears it or the period expires.
In February 2025, the FTC raised the Size-of-Transaction threshold to $119.5 million and a new, expanded HSR disclosure form took effect. The new form requires substantially more documentary and strategic information.
Many founders assume HSR is only a large-company problem, but growth-stage acquisitions with strategic acquirers can hit these thresholds faster than expected.
What Triggers an HSR Filing for a Startup Acquisition
The Size-of-Transaction Test
The primary trigger is deal value. As of 2025, if the total value of the acquisition (including cash, stock, debt assumption, and earnouts) exceeds $119.5 million, the transaction is presumptively reportable. Founders often underestimate deal value by ignoring non-cash components.
The Size-of-Person Test
For deals above the base threshold but below $478 million, both parties must also clear a Size-of-Person test. One party must have net sales or total assets exceeding $239 million, and the other must exceed $23.9 million. For deals valued above $478 million, no Size-of-Person test applies. The deal is automatically reportable.
What the New 2025 Filing Form Demands
The expanded form (effective February 10, 2025) now requires parties to submit:
- Transaction rationale documents and strategic analyses
- Competitor, customer, and supplier overlap information
- Detailed product and service revenue breakdowns
This is a material change. The old form was a data form. The new form is closer to a pre-merger investigation. Preparing it takes weeks and requires legal and financial coordination from day one.
Penalties for Skipping the Filing
Failure to file when required is not a paperwork issue. Civil penalties run up to $51,744 per day for each day the violation continues. The FTC can also seek to unwind a completed transaction. For a funded startup in an exit process, this is exactly the exposure that kills deals and damages investor relationships.
Common Founder Mistakes
Mistake #1: Calculating Deal Value Too Narrowly
Founders focus on the headline purchase price and leave out earnouts, assumed liabilities, and non-compete payments. A deal that looks like $90 million at headline may cross the $119.5 million threshold once all components are counted. File before closing, not after you realize you missed it.
Mistake #2: Assuming a Small Acquirer Means No Filing
If the buyer is a large strategic company or a private equity fund with significant assets, the Size-of-Person test can still trigger a filing requirement. The target’s size is only one half of the equation. Run the HSR analysis early in the process.
Mistake #3: Starting HSR Prep Too Late
The filing prep for the new 2025 form is not a one-day task. Pulling transaction rationale documents, competitive analyses, and prior acquisition history takes real time. Build HSR prep into your deal timeline from the LOI stage, not the week before your target close date.
10-Minute HSR Self-Check
Does the total deal value, including earnouts and assumed liabilities, exceed $119.5 million?
- Have I confirmed whether the acquirer’s total assets or revenues exceed $239 million?
- Does my deal team include counsel experienced with HSR filings and antitrust review?
- Have I started pulling transaction rationale documents required by the 2025 form?
- Is the 30-day HSR waiting period built into my closing timeline?
- Do I know whether the acquirer has made prior acquisitions in my space that could raise overlapping-market flags?
If you cannot answer yes to all of these, you are not ready to set a closing date yet.
Bottom Line
HSR is not a large-company technicality. For any growth-stage startup in a significant acquisition, it is a threshold question that needs to be answered before the LOI is signed. The 2025 rule changes made the filing heavier, the penalties unchanged, and the timeline implications real.
Need to Know if Your Acquisition Requires an HSR Filing Before Closing?
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Sources Used
- *Revised Jurisdictional Thresholds for Section 7A of the Clayton Act* — Federal Trade Commission (2025), https://www.ftc.gov/legal-library/browse/rules/premerger-notification-rules
- *HSR Threshold Adjustments and Reportability* — Federal Trade Commission, https://www.ftc.gov/enforcement/premerger-notification-program/hsr-threshold-adjustments-reportability
- *New HSR Rules: What You Need to Know* — Federal Trade Commission (February 2025), https://www.ftc.gov/news-events/news/press-releases/2025/02/ftc-updates-hsr-filing-requirements
- *Hart-Scott-Rodino Antitrust Improvements Act* — U.S. Department of Justice Antitrust Division, https://www.justice.gov/atr/hsr-resources