What is the HSR waiting period before a merger can close?

Information as of 15 October 2026. Everything below comes from the FTC's guide to the premerger notification process, linked below, and from OQRO's own M&A data as of 14 October 2026. If anything here is wrong, tell us at contact@oqro.io and we will correct it.

What is the HSR waiting period?

The Hart-Scott-Rodino Act, usually shortened to HSR, requires parties to certain large mergers and acquisitions to tell the government about the deal before they complete it. The FTC's description of the process says that parties to such deals must file premerger notification and wait for government review, and that they may not close the deal until the waiting period outlined in the HSR Act has passed, or the government has granted early termination of the waiting period.

The FTC administers the premerger notification program. Its page notes that some transactions are exempt and points to its guides for the filing requirements. It also says there is a filing fee, and that for most transactions requiring a filing, both the buyer and the seller must file forms and provide data about the industry and their own businesses.

How long is the waiting period?

According to the FTC, once the filing is complete the parties must wait 30 days, or 15 days in the case of a cash tender offer or a bankruptcy, or until the agencies grant early termination of the waiting period, before they can consummate the deal.

That makes the clock short by design for the simplest cases, and it explains why deal announcements often say that closing is expected after the waiting period ends. The press release usually names the quarter in which the company expects the transaction to close, and OQRO shows that text on a deal page as the expected close when the filing states it.

Which agency reviews a deal?

The parties file with both the FTC and the Department of Justice, but the FTC says only one antitrust agency will review the proposed merger. Staff from the two agencies consult and the matter is cleared to one or the other for review. This is known as the clearance process. Once clearance is granted, the reviewing agency can obtain non-public information from various sources, including the parties and other participants in the industry.

What can happen at the end of the first period?

After a preliminary review, the FTC says the agency can do one of three things: terminate the waiting period before it ends, which is called early termination, allow the initial waiting period to expire, or issue a Request for Additional Information, known as a Second Request, to each party.

If the waiting period expires or is terminated, the parties are free to close. If the agency needs more information, a Second Request extends the waiting period and prevents the companies from completing the deal until they have substantially complied with it and observed a second waiting period. The FTC says a Second Request typically asks for business documents and data that will inform the agency about the company's products or services, market conditions where it does business, and the likely competitive effect of the deal.

How does this show up in the filings?

The antitrust review is not an 8-K item of its own. It appears in the text of the merger announcement and in later filings, where a company reports that the waiting period has expired or that it has received a Second Request, if it chooses to disclose either. A completed deal is then reported under Item 2.01 of Form 8-K, as described in our guide to Item 1.01.

On OQRO's M&A page, a deal that has been signed but not yet closed carries the status Pending. As of 14 October 2026, OQRO's data held 406 deals found in filings since late July: 200 pending, 45 announced, 151 completed and 10 terminated. A deal stays pending until a filing says otherwise, so a deal whose closing filing was not detected can look pending longer than it is.

What this does not tell you

A waiting period is a minimum time and a legal gate, not a prediction. The FTC page does not say how many deals receive a Second Request, how long reviews last, or which deals will be challenged, and this article does not either. It also does not cover other approvals a deal can need, such as foreign antitrust authorities or sector regulators, or the shareholder vote.

OQRO shows what companies state in their own filings; where a filing gives no closing date, the page says Not disclosed. Nothing here is investment advice.