Statutory Mechanics of the Hart-Scott-Rodino (HSR) Waiting Period
Under the Hart-Scott-Rodino (HSR) Antitrust Improvements Act of 1976 (15 U.S.C. § 18a), merging parties exceeding specified size thresholds are required to file premerger notifications with the Federal Trade Commission (FTC) and the Department of Justice (DOJ) Antitrust Division. After both agencies receive complete filings, the parties must observe a strict statutory waiting period during which the proposed acquisition cannot be consummated. This calculator provides interactive tracking and structural scenario modeling for HSR transactions, calculating exact statutory expirations and regulatory extensions based on the official 2026 calendar.
The 5:00 PM Eastern Filing Cutoff and Receipt Rules (Day 0)
A fundamental trap in transaction scheduling is the strict filing receipt rule. In order to receive credit for filing on a given business day, the premerger notifications (along with confirmation of payment of the tiered filing fee) must be fully completed, verified, and received by both the FTC and DOJ before 5:00 PM Eastern Time (ET). Filings submitted at or after 5:00 PM ET, or on a Saturday, Sunday, or official Federal holiday, are treated as officially received on the next business day.
The date of official receipt is designated as Day 0. The statutory waiting period commences on the day following official receipt, designated as Day 1. This means if a filing is submitted on a Friday at 5:15 PM ET, Day 0 does not occur until Monday, and Day 1 (the start of the clock) is Tuesday, effectively pushing the transaction timeline out by four calendar days.
Statutory Wait Times & Expiration Rollovers
The base length of the HSR waiting period depends directly on the structure of the transaction:
- Standard Transactions: For standard acquisitions, asset transfers, or joint ventures, the waiting period is exactly 30 calendar days.
- Cash Tender Offers: For acquisitions made via cash tender offers subject to SEC regulations, the waiting period is compressed to 15 calendar days.
- Bankruptcy Transactions: Acquisitions of distressed assets under Section 363(b) of the Bankruptcy Code also enjoy a compressed waiting period of 15 calendar days.
Under statutory rule, if the final day of the waiting period falls on a Saturday, Sunday, or legal Federal public holiday, the waiting period does not expire on that day. Instead, it is automatically extended until 11:59 PM ET on the next calendar day that is not a weekend or a legal Federal holiday.
The Pull-and-Refile Process (16 C.F.R. § 803.12)
During the initial review period, if the FTC or DOJ raises initial competition issues, the parties may decide that the regulatory staff needs more time to complete its investigation. Rather than forcing the agency to issue a burdensome "Second Request" (which stops the transaction indefinitely and triggers massive document-collection costs), the acquiring person can elect to use the **Pull-and-Refile** procedure under 16 C.F.R. § 803.12.
The acquiring person can voluntarily withdraw its HSR premerger filing and then **refile an updated HSR Form within two business days** from the day after withdrawal. By doing so, the parties restart a new statutory waiting period (e.g., a new 30-day review period) without being required to pay a new, expensive filing fee. If the refiling date misses this strict 2-business-day window, a brand-new filing must be processed with a new tiered filing fee.
Second Requests and Substantial Compliance Extensions
If the antitrust authorities determine that a transaction requires deep competitive analysis, they may issue a formal **Request for Additional Information** (commonly known as a **Second Request**) before the active waiting period expires. The issuance of a Second Request immediately halts the clock.
The transaction cannot close until both parties (or only the acquiring party in the case of a tender offer) compile responses, provide requested internal communications and data, and certify **Substantial Compliance** with the Second Request. The date of formal compliance certification restarts the clock on a new extended waiting period:
- Standard transactions: Starts a new 30 calendar day extended waiting period.
- Cash Tender / Bankruptcy transactions: Starts a new 10 calendar day extended waiting period.
Like the initial wait times, if the final day of this extended Second Request review period falls on a weekend or Federal holiday, it is rolled over to the next business day. Due to the high stakes and strict timelines, corporate parties must model these potential scenarios carefully to manage deal risk, credit facility expirations, and regulatory approval schedules.