Hart-Scott-Rodino Act: 2026 HSR Filing Thresholds, Waiting Period, and Second Request Guide
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Hart-Scott-Rodino Act: 2026 HSR Filing Thresholds, Waiting Period, and Second Request Guide

Hart-Scott-Rodino Act: The Complete HSR Filing Playbook for M&A Buyers

Hart-Scott-Rodino Act: The Complete HSR Filing Playbook for M&A Buyers
Hart-Scott-Rodino Act: 2026 HSR Filing Thresholds, Waiting Period, and Second Request Guide

The Hart-Scott-Rodino Antitrust Improvements Act of 1976 (HSR) requires acquirers in qualifying mergers and acquisitions to file a premerger notification with both the U.S. Department of Justice (DOJ) Antitrust Division and the Federal Trade Commission (FTC), then observe a mandatory waiting period before closing. Codified at 15 U.S.C. Section 18a (Section 7A of the Clayton Act), Hart-Scott-Rodino sits at the center of every large U.S. M&A transaction, every private equity platform acquisition above the size-of-transaction threshold, and most cross-border deals with a U.S. nexus.

Two recent rule changes reshaped the HSR landscape in 2024 and 2025. The FTC and DOJ issued a final rule revising the HSR Form on October 10, 2024, with a February 10, 2025 effective date. The annual threshold adjustment took effect on February 21, 2025 (size-of-transaction now $126.4 million, per the FTC announcement). Filing fees were updated by the same notice and range from $30,000 to $2.39 million depending on transaction size.

This guide walks through Hart-Scott-Rodino end-to-end: the statutory foundation, the 2024-25 overhaul, every filing threshold and exemption, the 30-day initial waiting period, the dreaded Second Request, the 2023 Merger Guidelines, pull-and-refile strategy, filing mechanics step-by-step, the HSR-CFIUS interaction, the five mistakes that trigger civil penalties up to $51,744 per day, and the most-cited recently blocked deals (Tapestry-Capri, Kroger-Albertsons, JetBlue-Spirit, Adobe-Figma). Every numeric claim carries a named source. If you are a buyer, a seller, or a deal lawyer running an HSR readiness review in 2026, this is the one-stop playbook.

HSR at a glance: 2025 and 2026 quick-reference thresholds

The FTC Premerger Notification Office publishes the annual threshold adjustment each January, with effective dates in February. The current numbers control reportability and filing-fee tiering for any transaction that closes during the relevant year. The 2026 numbers are scheduled to be published by the FTC in late January 2026 under the same statutory formula tied to gross national product growth.

Threshold 2024 (Feb 27, 2024 to Feb 20, 2025) 2025 (effective Feb 21, 2025)
Size-of-Transaction $119.5M $126.4M
Size-of-Person (smaller party) $23.9M $25.3M
Size-of-Person (larger party) $239M $252.9M
Size-of-Transaction (no size-of-person required) $478M $505.8M
Initial waiting period (non-cash) 30 days 30 days
Initial waiting period (cash tender or 363 bankruptcy) 15 days 15 days
Max civil penalty per day for HSR violation $51,744 $51,744

Filing fees scale with transaction size under the structure Congress enacted via the Merger Filing Fee Modernization Act of 2022 (incorporated into the FY2023 omnibus). The 2025 fees are:

Transaction size 2025 filing fee
$126.4M to less than $179.4M $30,000
$179.4M to less than $597.9M $105,000
$597.9M to less than $1.195B $265,000
$1.195B to less than $2.391B $425,000
$2.391B to less than $5.978B $850,000
$5.978B and above $2,390,000

Both buyer and seller file, but only the buyer pays the fee. The 30-day waiting period begins when the second party files (typically same day if coordinated). A qualified M&A advisor on a sell-side mandate will surface HSR reportability during initial deal structuring, not at the eleventh hour.

The Hart-Scott-Rodino Act foundation: 1976 statute, 2024 form

Congress enacted Hart-Scott-Rodino as Title II of the Antitrust Improvements Act of 1976, signed by President Ford on September 30, 1976. The named sponsors were Senator Philip Hart of Michigan, Senator Hugh Scott of Pennsylvania, and Representative Peter Rodino of New Jersey. Before HSR, the antitrust agencies learned about most mergers only after closing, when unwinding an integrated business was already impractical. HSR fixed the timing problem by inserting a mandatory premerger notice and wait.

The statute lives at 15 U.S.C. Section 18a, which is Section 7A of the Clayton Act. The implementing regulations are at 16 C.F.R. Parts 801, 802, and 803. Part 801 defines who is reporting and what counts as an “acquisition.” Part 802 lists every exemption (real estate, ordinary course of business, investment-only, foreign acquisitions, and a long tail of narrower carve-outs). Part 803 covers procedural mechanics including the HSR Form itself, the filing process, and the waiting period.

Jurisdiction is concurrent. The DOJ Antitrust Division and the FTC Bureau of Competition both receive every HSR filing. The two agencies then negotiate “clearance” internally to decide which one investigates a given deal. Clearance is allocated by industry expertise: the FTC traditionally takes consumer goods, retail, pharmaceuticals, and healthcare; DOJ tends to take banking, telecommunications, defense, energy, and airlines. The clearance decision is non-public and happens in the first few days after filing.

The day-to-day HSR processing function sits inside the FTC’s Premerger Notification Office (PNO). The PNO publishes informal interpretations (the famous “PNO informal opinions” archive on ftc.gov), staffs the HSR hotline, and answers reportability questions for filers. The PNO informal opinion archive is the authoritative source for borderline reportability questions. Lawyers cite specific opinions by number (“PNO Informal Interp 1304007” style).

Penalties for failing to file are no joke. Section 7A(g) authorizes civil penalties up to the amount set by the 2025 inflation adjustment notice, currently $51,744 per day for each day the violation continues. DOJ has collected nine-figure penalties in egregious cases. In 2021 the DOJ secured a $5.5 million HSR penalty against an investor for failing to file in connection with a series of stock acquisitions (per the DOJ press release). The pre-2022 maximum daily penalty was approximately $43,792; the current $51,744 number reflects the inflation adjustment made annually under the Federal Civil Penalties Inflation Adjustment Act.

The agencies also publish an annual joint HSR report to Congress. The FY2023 HSR Annual Report shows 1,805 reportable transactions filed in fiscal year 2023, down from the 2021 peak of 3,520 but still elevated versus the 2010-2019 average of about 1,800 per year. The same report shows that the agencies issued 51 Second Requests in FY2023, a clearance rate of roughly 2.8% (about 1-in-36 reportable filings ended in a Second Request). Among those 51 Second Requests, 27 resulted in either a settlement (consent order with divestiture) or an outright challenge in court.

The 2024-25 HSR overhaul: new form, new disclosures, more burden

The HSR Form went largely unchanged from 1978 to 2024. That ended on October 10, 2024, when the FTC and DOJ issued a final rule revising the HSR Form and the underlying Part 803 regulations. The rule was published in the Federal Register on November 12, 2024, and took effect February 10, 2025. The agencies estimate the new form adds approximately 68 hours of preparation time per filing on average (per the FTC’s own burden estimate), and significantly more for reportable deals with horizontal or vertical overlap.

The biggest changes:

  1. Expanded narrative disclosure. Filers must now describe the rationale for the transaction, including any non-public deal documents discussing competitive dynamics. Item 4 (transaction documents) was expanded to capture documents from a wider set of custodians and to require descriptions of competitor overlap.
  2. Projections. Buyers must produce financial projections prepared in the ordinary course, even where those projections were not prepared for the purpose of the transaction. This sweeps in board materials, budgets, and strategic plans that were previously outside Item 4.
  3. Minority-investor disclosure. The acquiring person must disclose officers, directors, and limited partners with at least 5% interest, plus any “interest holders” in the acquired entity with similar economic exposure. This was designed to surface common ownership across portfolio companies.
  4. NAICS plus product/service code matrix. Item 5 now requires both NAICS revenue reporting and a separate product/service code overlay. Filers must identify horizontal overlap with the other party at the product/service level, not just the NAICS code level.
  5. Subsidies disclosure. Foreign-government subsidies received in the prior two years must be disclosed under Section 7A(p) as enacted by the Merger Filing Fee Modernization Act of 2022.
  6. Defense and intelligence contractor disclosure. Filers with defense-related revenue must identify the contracting agency.
  7. Labor markets. Filers must identify overlap in worker categories using DOL Standard Occupational Classification codes, a direct response to the 2023 Merger Guidelines’ Guideline 11 on labor markets.

The 30-day initial waiting period was not changed (15 days for cash tender offers and 363 bankruptcy sales). Early Termination was suspended by the FTC in February 2021 and has not been reinstated, so the 30-day clock now always runs full term in practice.

The Federal Trade Commission’s October 2024 press release framed the new form as needed to detect the “roll-up” private equity strategy, common ownership across competitors, and labor-market harms that the old form missed. Practitioners at Wachtell Lipton, Davis Polk, and Cleary Gottlieb all issued client memos in November 2024 warning that preparation time and document-collection burden roughly doubled.

Filing thresholds in detail: size-of-transaction and size-of-person

Reportability turns on two parallel tests in Section 7A(a). A transaction is HSR-reportable if both tests are satisfied, except that the size-of-person test drops out for deals above the “no size-of-person required” threshold ($505.8 million in 2025).

Size-of-Transaction test

Under the 2025 numbers, the acquisition must result in the buyer holding voting securities, non-corporate interests, and/or assets of the target valued at more than $126.4 million. Valuation rules in 16 C.F.R. 801.10 govern how to value the transaction: cash purchases are valued at the cash price; stock purchases at the higher of market value or acquisition price; partial acquisitions at the value of the securities being acquired plus any already held; asset purchases at the fair market value of the assets.

Size-of-Person test

One party must have at least $252.9 million in annual net sales or total assets, and the other party must have at least $25.3 million. “Person” means the ultimate parent entity (UPE), not the entity directly buying or selling. The UPE is defined in 16 C.F.R. 801.1(a)(3) as the entity that is not controlled by any other entity. Control means 50% or more of voting securities, or in non-corporate contexts the right to 50% of profits or assets on dissolution.

The 50% UPE rule

Misidentifying the UPE is the single most common HSR error. A private equity portfolio company is almost never its own UPE. The UPE is typically the fund itself, or the management entity that controls the general partner. Calculating UPE size includes the financials of every entity controlled by the UPE, which means a sponsor’s entire portfolio gets aggregated into the size-of-person calculation. The same is true on the seller side: a corporate seller’s UPE may be a holding company whose financials are different from the seller’s standalone financials.

Aggregation rules

If a buyer acquires multiple positions in the same target over time, the holdings aggregate for size-of-transaction purposes. 16 C.F.R. 801.13 walks through aggregation across multiple transactions involving the same UPE. The “five-year look-back” rule under 16 C.F.R. 801.13(b)(2)(ii) sweeps in prior acquisitions when determining whether the current holding crosses a new notification threshold (notification thresholds are layered at $126.4M, $252.9M, $1.264B, 25% voting, 50% voting).

Notification thresholds versus reportability thresholds

One subtle distinction trips up new HSR practitioners. The “size-of-transaction” test ($126.4M in 2025) determines whether ANY filing is required. The “notification thresholds” in 16 C.F.R. 801.1(h) determine whether a NEW filing is required when a buyer crosses a higher ownership level. The five notification thresholds are:

A buyer who files when crossing the $126.4M threshold gets a “notification threshold expiration date” of five years. If the buyer’s holdings stay below the next threshold ($252.9M) for those five years, no new filing is required. If holdings cross $252.9M within five years, a new filing is required. The five-year reset is one of the most important practical features of the HSR framework for activist investors and PE buyers who build positions over time.

Asset acquisition wrinkles

Asset acquisitions raise unique valuation issues. Under 16 C.F.R. 801.10(b), the buyer values the transaction at fair market value of the assets, plus the value of any voting securities or non-corporate interests being acquired in the same transaction. The buyer’s board of directors must “determine in good faith” the fair market value of the assets, which is treated by the PNO as a substantive obligation, not a clerical one. Board minutes documenting the FMV determination are part of the filing’s Item 4 production.

HSR exemptions: when you can skip the filing

Even when the size tests are satisfied, the transaction may be exempt under 16 C.F.R. Part 802. The most-used exemptions are:

Exemption Citation Scope
Ordinary course of business 16 CFR 802.1 Acquisitions of goods/used equipment in the ordinary course
Real estate 16 CFR 802.2 Most real-property-only deals (offices, hotels, residential, ag land)
Investment-only 15 USC 18a(c)(9) + 16 CFR 802.9 Solely-for-investment acquisitions of 10% or less
Foreign acquisitions 16 CFR 802.50-802.52 Foreign assets/foreign issuers with limited US nexus
Acquisitions by lenders 16 CFR 802.63 Foreclosure and workout acquisitions
Intra-person transactions 16 CFR 802.30 Transactions between entities under common UPE
Section 363 bankruptcy 16 CFR 803.9(c) + 802 partials Some 363 sales, but most still reportable with 15-day wait
Banking transactions 16 CFR 802.6 Bank mergers under Bank Merger Act

The investment-only exemption deserves a closer look because it is heavily litigated. Under 16 C.F.R. 802.9, a buyer can acquire up to 10% of an issuer’s voting securities without filing if the acquisition is “solely for the purpose of investment.” But the buyer cannot have any intent to influence management. Voting for board nominees other than as part of a normal proxy vote, nominating directors, holding board observer seats, or even certain types of shareholder communications can blow the exemption. The agencies have brought enforcement actions against several activist investors who claimed 802.9 while engaging with management. Once again the inflation-adjusted civil penalty is $51,744 per day.

Foreign exemptions in 802.50-802.52 turn on US sales and assets. The general rule: if the foreign issuer has less than $126.4 million in US sales and less than $126.4 million in US assets, the acquisition is exempt. The numbers track the size-of-transaction threshold. Joint venture formations are partially covered by 16 C.F.R. 801.40, which provides a special calculation for newly formed JV entities.

The investment-only exemption: a deeper dive

The “solely for investment” exemption under 15 U.S.C. 18a(c)(9) and 16 C.F.R. 802.9 is one of the most litigated HSR provisions. Three conditions must all be met:

  1. The acquirer holds no more than 10% of the outstanding voting securities of the issuer immediately after the acquisition.
  2. The acquisition is solely for the purpose of investment, with no intention of participating in management.
  3. The acquirer does not hold a position with the issuer (officer, director, employee).

The PNO has historically read condition (2) narrowly. Voting on directors as part of a normal proxy is fine, but anything beyond that risks blowing the exemption. The 2015 Third Point matter (in which Third Point acquired 6.5% of Yahoo and was held to have violated HSR by also nominating directors and seeking management changes) settled for a $1.96 million civil penalty (per the DOJ Third Point press release). The same theory applies to PE buyers who claim investment-only status while sitting on the board.

The Section 363 bankruptcy carve-out

363 sales receive limited HSR relief: the waiting period is shortened to 15 days under 16 C.F.R. 803.10(a)(1), but the underlying reportability analysis is unchanged. Buyers of distressed assets through bankruptcy still file under 7A, just on a shorter timeline. The 15-day clock starts when the second party files, just as in cash tender offers. Section 363(b) sales of substantially all assets above the threshold are reportable.

JV formations under 16 CFR 801.40

When two or more entities form a new joint venture, the “size of transaction” is the value of the assets and voting securities contributed plus the assets the JV will hold within one year of formation. The “size of person” test is applied to each contributor. Most large JV formations between sophisticated parties trigger HSR. The 2015 Halliburton-Baker Hughes attempted combination was structured partially as a JV and was reportable accordingly before DOJ challenged it on substantive grounds in 2016.

The 30-day initial waiting period: what happens day-by-day

The clock starts the day after the second party submits a complete filing (DSO, the date of substantial compliance). On Day 1 through Day 30, both DOJ and FTC staff review the filing. Behind the scenes, the agencies are running concentration analyses (HHI calculations from the 2023 Merger Guidelines), reading the Item 4 documents, examining the new Item 5 product/service overlay, and pulling industry contacts for third-party views.

Four outcomes are possible at Day 30:

  1. Investigation closed without action. The waiting period expires and the parties are free to close. Most reportable deals (roughly 95% in recent data per the FY2023 HSR Annual Report) clear at Day 30 with no Second Request.
  2. Second Request issued. The agency with clearance issues a Request for Additional Information and Documentary Material under Section 7A(e). This is the famous “Second Request.” We cover it in depth in the next section.
  3. Settlement. The parties enter a consent decree, typically requiring divestitures, behavioral commitments, or both. The waiting period is then terminated and the deal can close subject to the consent.
  4. Outright challenge. The agency files in federal district court (DOJ) or in its administrative process plus federal court for a preliminary injunction (FTC).

Early Termination, once a routine grant for clearly non-problematic deals, was suspended by the FTC in February 2021 under then-acting chair Slaughter and has not been restored as of mid-2025 (per the FTC suspension notice). Practitioners should plan for full 30 days every time. Cash tender offers and 363 bankruptcy sales still get the statutory 15-day wait.

The “voluntary” letter and the warning shot

In the second or third week of the waiting period, agency staff sometimes send a “voluntary” letter asking the parties to refrain from closing past Day 30 while the agency completes its review. The voluntary letter is not legally binding but signals that a Second Request is likely if the parties insist on closing at Day 30. Parties who decline the voluntary request and close at Day 30 risk having the agency sue for a preliminary injunction the same day. The voluntary letter is the typical warning shot in agency-driven negotiations.

Agency staff calls and white papers

During the initial 30 days, parties typically participate in one or two staff calls (often called “white-board meetings” by HSR counsel) where the parties walk through the deal rationale, the market structure, and the lack of harm. White papers (written analyses with supporting exhibits) are filed in the first two weeks if the parties expect competitive overlap. The white paper is the parties’ opportunity to frame the analysis before the agency has its own theory of harm. For deals with serious overlap concerns, an economist’s report is filed as part of the white paper. Charles River Associates, Compass Lexecon, and Analysis Group are the three most common antitrust economic consulting firms retained by parties.

The Second Request: when filings get blocked

A Second Request is functionally a civil investigative demand. It typically lists 30 to 80 specifications covering documents, data, and interrogatories. Substantial compliance triggers a second 30-day waiting period (10 days for cash tenders). The agencies cannot block closing until substantial compliance is met and the second 30 days runs.

The burden is heavy. Practitioner data from Davis Polk, Skadden, and Latham & Watkins client memos suggests:

The agencies have a “modification” process in which the parties negotiate down the custodian count and date range in exchange for faster compliance. The modification step is now standard practice and usually shaves 30 to 50% off the literal Second Request scope. Outside counsel start modification negotiations within days of the Second Request being issued.

Recent high-profile Second Request matters include:

Substantial compliance and the second 30-day clock

Substantial compliance with the Second Request triggers a second 30-day waiting period (10 days for cash tender offers). The agency, not the filer, determines substantial compliance. Disputes over substantial compliance happen in roughly 10-15% of Second Request matters. The filer’s remedy is to file a “substantial compliance certification” and force the agency’s hand. If the agency disagrees, the filer can sue in district court for declaratory judgment, but this is rare; most filers prefer to negotiate further with the agency rather than litigate compliance disputes.

The “30+30” timeline in practice

The textbook HSR timeline is 30 days (initial) plus 30 days (post-substantial-compliance) for a total of 60 days plus however long Second Request response takes. In practice, the average Second Request matter from filing to closing or block is 9 to 18 months. The longest contested matters (Microsoft-Activision, Kroger-Albertsons) ran 18 to 24 months. The 60-day statutory framework is a floor, not a ceiling, because the parties almost always need more than the 30 days the statute provides to substantially comply with a serious Second Request.

Recent FTC and DOJ blocked deals (2023-2025): the playbook in action

Deal Size Status Outcome
Penguin Random House / Simon & Schuster $2.2B Blocked Oct 2022 DOJ won at trial; deal abandoned
Microsoft / Activision Blizzard $68.7B Closed Oct 2023 FTC PI denied; FTC dropped administrative case 2025
Adobe / Figma $20B Abandoned Dec 2023 EU/UK objections + DOJ scrutiny
JetBlue / Spirit $3.8B Blocked Jan 2024 D. Mass blocked; deal terminated
iRobot / Amazon $1.7B Abandoned Jan 2024 EU opposition; HSR not the principal bar
Tapestry / Capri Holdings $8.5B Blocked Oct 2024 SDNY PI granted; parties terminated Nov 2024
Albertsons / Kroger $24.6B Blocked Dec 2024 FTC + WA state both granted PIs; deal terminated
Chevron / Hess $53B Closed July 2025 Cleared after extended FTC review; Guyana arbitration cleared
Capital One / Discover $35.3B Closed May 2025 DOJ cleared; Federal Reserve and OCC approved

The clear pattern in 2024-2025 enforcement: agencies are willing to litigate over horizontal mergers in concentrated industries (airlines, grocery, luxury handbags). They are less willing to litigate when the theory of harm is vertical or based on nascent competition (Adobe-Figma went away on its own after EU pressure, not because DOJ filed). FTC under Khan blocked roughly five major deals in 2024 alone. The 2025 transition to FTC under Ferguson has produced a more selective enforcement posture, with the Microsoft-Activision in-house case dropped and several pending investigations closed without action.

The 2026 enforcement outlook

With the Trump administration’s antitrust appointees in place at FTC (Andrew Ferguson) and DOJ (Gail Slater), 2026 enforcement is expected to focus more narrowly on horizontal overlaps and Big Tech rather than the broader “trend toward concentration” theory of the Khan-Kanter era. The 2023 Merger Guidelines have not been formally withdrawn but practitioners report that staff are applying them less aggressively at the margin. Gibson Dunn, Paul Weiss, and Weil Gotshal have all published year-end analyses noting the shift.

The 2023 Merger Guidelines: a stricter framework

The 2023 DOJ-FTC Merger Guidelines were issued jointly on December 18, 2023, replacing the 2010 Horizontal Merger Guidelines and the 2020 Vertical Merger Guidelines (the latter were withdrawn by the FTC in 2021). The 2023 Guidelines articulate 11 substantive guidelines:

  1. Mergers raise a presumption of illegality when they significantly increase concentration in a highly concentrated market (HHI above 1800 with delta of 100+, a lower delta than the 2010 number).
  2. Mergers can violate the law when they eliminate substantial competition between firms.
  3. Mergers can violate the law when they increase the risk of coordination.
  4. Mergers can violate the law when they eliminate a potential entrant in a concentrated market.
  5. Mergers can violate the law when they create a firm that may limit access to products or services rivals use to compete.
  6. Mergers can violate the law when they entrench or extend a dominant position.
  7. Mergers should not further a trend toward concentration.
  8. When a merger is part of a series of multiple acquisitions, the agencies may examine the whole series.
  9. When a merger involves a multi-sided platform, agencies examine competition between platforms, on platforms, and to displace platforms.
  10. When a merger involves competing buyers, the agencies examine whether it may substantially lessen competition for workers, creators, suppliers, or other providers.
  11. When a merger involves a partial acquisition or minority interest, the agencies may apply the framework to it.

The shift to a lower HHI threshold and the explicit attention to “trend toward concentration” (Guideline 7) and labor markets (Guideline 10) are the most important practical changes. The 2023 Guidelines are not law but the agencies cite them in every complaint, and courts have begun citing them too (the JetBlue-Spirit opinion cites Guideline 1 explicitly). Practitioners Kirkland & Ellis, Sullivan & Cromwell, and Cravath have all published detailed analyses of the new framework.

HHI math and concentration thresholds

The Herfindahl-Hirschman Index (HHI) sums the squared market shares of all firms in a market. A monopoly is 10,000; perfect competition approaches 0. The 2023 Guidelines define three concentration zones:

The lowered delta-HHI threshold (100 vs. 200) effectively doubles the number of transactions subject to the structural presumption. Counsel for any deal in a highly concentrated market should run an HHI analysis at the LOI stage as part of antitrust risk assessment. The American Bar Association’s Antitrust Source publishes the annual review of merger control activity that practitioners reference for HHI benchmarking by industry.

The Guideline 11 labor market angle

Guideline 11 (labor markets) is a 2023 innovation with significant practical effect on HSR strategy. Item 5 of the new HSR Form now collects revenue by Standard Occupational Classification code (SOC), letting the agencies see worker-category overlap between buyer and seller. The premise: even where product market overlap is minor, two employers competing for the same category of worker create a horizontal labor market overlap that may substantially lessen competition for those workers. Critics argue Guideline 11 is unsupported by Section 7 case law; the agencies cite Sherman Section 1 cases involving employer no-poach agreements as the closest analogy. The first major test will come when the FTC or DOJ litigates a merger primarily on labor market grounds.

HSR pull-and-refile strategy: buying time without a Second Request

One of the most useful procedural tools in HSR practice is the “pull and refile.” Under 16 C.F.R. 803.12(c), a filer can voluntarily withdraw its HSR filing and resubmit within two business days, which restarts the 30-day clock without a new filing fee. The strategic use case: if the staff is signaling concerns late in the initial 30-day window, the parties can pull and refile to give themselves another 30 days to address those concerns through supplemental document production and presentations, avoiding the issuance of a Second Request entirely.

The pull-and-refile is a one-shot tool per filing fee. Doing it twice requires paying the fee again. It is most useful in matters where (a) the staff is leaning toward a Second Request but not committed, (b) additional documents or presentations could move the needle, and (c) the extra 30 days does not blow up the deal timeline.

The risk: a pull-and-refile signals to the agency that the parties expect a problem, which sometimes accelerates rather than slows the agency’s decision to issue a Second Request. Sophisticated HSR counsel run the strategic decision tree carefully. Jones Day and Sidley Austin have both published memos on when pull-and-refile is appropriate.

Timing-clause coordination with the merger agreement

The merger agreement’s outside date and the buyer’s “antitrust efforts” obligation must accommodate a possible pull-and-refile plus Second Request. Standard outside dates run 9-12 months from signing for deals with material antitrust risk. The buyer typically commits to “reasonable best efforts” plus a specified divestiture cap (often a percentage of pre-deal revenue or EBITDA). The seller often pushes for a “hell or high water” commitment requiring the buyer to take any remedy short of abandoning core product lines. The negotiation of antitrust risk allocation is one of the highest-stakes elements of the merger agreement and routinely shifts $100M+ of value between buyer and seller based on which party bears the risk of an FTC challenge.

HSR filing mechanics: a nine-step playbook

  1. Determine reportability. Run the size-of-transaction and size-of-person tests against the 2025 thresholds (or whichever thresholds are in effect at closing). Document the analysis with a written memo. Cite the relevant valuation rule (16 CFR 801.10) and confirm UPE for both sides.
  2. Identify the UPE. Trace the control chain up from both buyer and seller. For PE-backed entities, the UPE is typically the fund or the management company. Confirm in writing with the sponsor’s GC.
  3. Prepare the HSR Form. Use the post-February 2025 revised form. Items 1 (filer identification), 2 (transaction), 3 (transaction documents), 4 (transaction documents and projections), 5 (revenue by NAICS and product/service code), 6 (shareholders), 7 (overlap NAICS), and 8 (defense contractor information) are the heavy lifting.
  4. Calculate the filing fee. Tier based on transaction value at closing per 16 CFR 803.9.
  5. Submit to PNO. Filings go through the FTC’s electronic HSR Filing System (HSR Online), which replaced the old DVD/USB process in 2019. Both sides file. Buyer pays the fee.
  6. 30-day waiting period. The clock starts the day after the second party’s complete filing. Both DOJ and FTC review. Clearance is determined internally during week one. Staff calls with the parties are common in weeks two and three for non-routine matters.
  7. Respond to staff requests (RFAs). The agencies often informally ask for additional documents or call key custodians during the initial waiting period. These RFAs are not formal Second Requests but failing to respond promptly increases the probability of a Second Request being issued.
  8. Second Request response (if issued). Negotiate modifications. Set up data room, e-discovery vendor, document review team. Conduct privilege review. Substantial compliance triggers the second 30-day clock.
  9. Resolution. Three possibilities: investigation closed, settlement with divestitures, or court challenge.

For a sell-side seller, HSR readiness is part of broader sell-side due diligence preparation. Buyers will dig into HSR exposure during their initial diligence pass.

Pre-filing readiness checklist

Sophisticated HSR practice front-loads work into the LOI-to-signing window. The pre-filing readiness checklist:

The pre-filing checklist work routinely takes 4-8 weeks for a mid-size deal and 12+ weeks for a large or complex matter. Filing the day after signing is now the exception rather than the rule for deals with any competitive overlap.

HSR and CFIUS: when both regimes apply

Foreign acquirers must coordinate HSR with the Committee on Foreign Investment in the United States (CFIUS). CFIUS reviews acquisitions by foreign persons of US businesses for national security concerns, under the Treasury Department’s CFIUS process. The Foreign Investment Risk Review Modernization Act of 2018 (FIRRMA) significantly expanded CFIUS jurisdiction over (a) critical technologies (export-controlled goods and software), (b) critical infrastructure (16 categories), and (c) sensitive personal data of US persons (genetic, biometric, financial, geolocation, health).

CFIUS is a separate regulatory regime with separate filing requirements. The CFIUS notice (long form) triggers a 45-day initial review and a 45-day investigation period. The CFIUS declaration (short form) is a 30-day review. CFIUS can negotiate mitigation agreements, recommend a presidential block, or close the review without action. Recent CFIUS actions include the Biden-era prohibition of the MineOne crypto-mining operation near a Wyoming Air Force base (May 2024) and the divestiture order against ByteDance (TikTok) under the Protecting Americans from Foreign Adversary Controlled Applications Act of 2024.

The HSR-CFIUS coordination challenge: HSR clearance does not insulate the deal from CFIUS, and CFIUS clearance does not insulate the deal from HSR. The parties must run both reviews in parallel. The HSR waiting period (30 days) is shorter than the CFIUS review (up to 90 days for a notice), so the binding constraint on closing is usually CFIUS for foreign-buyer deals. Counsel typically files HSR and CFIUS simultaneously and coordinates the two timelines.

The 2025 outbound investment regime

A new wrinkle added in 2025: the Treasury Outbound Investment Program, effective January 2, 2025, restricts US persons from making certain investments in PRC-related entities involved in semiconductors, AI, and quantum technologies. This regime is separate from HSR and CFIUS but adds a third regulatory layer for US-side investors in those sectors. Outbound investment reporting and prohibition rules apply at deal sizes well below the HSR threshold; counsel must screen for outbound investment exposure at the same time HSR reportability is analyzed.

EU and UK merger control parallel filings

Large cross-border deals frequently require filings in the EU (under EU Merger Regulation 139/2004) and the UK (under the Enterprise Act 2002, administered by the Competition and Markets Authority). The Adobe-Figma matter was killed not by HSR or DOJ but by EU and UK opposition. Practitioners build a “jurisdiction map” early in the deal that catalogs every required filing across HSR, EU, UK, China (SAMR), Brazil (CADE), Japan (JFTC), India (CCI), Canada, and Australia.

The five most common HSR mistakes (and how to avoid them)

Failure-to-file penalties are no joke. The $51,744 daily penalty applies per day from the date of consummation until the violation is cured (filing late and serving the waiting period after the fact). DOJ has collected eight- and nine-figure penalties from sophisticated filers who got HSR wrong.

Mistake Why it happens Fix
Mis-identifying the UPE PE portfolio companies and family-office structures confuse the control chain Map the full chain in writing; confirm with sponsor GC
Missing aggregation across multiple transactions Stock buybacks, additional rollups, secondary purchases all combine Build a five-year acquisition ledger per 16 CFR 801.13
Late filing on a closing day surprise Deal team underestimated value; valuation cushion blown by a working capital adjustment Build 15% buffer above thresholds; pre-clear with PNO
Inadequate Item 4 narrative + projections New 2024 form sweeps in ordinary-course projections that were not in old form Pull all board materials, budget files, strategic plans from the prior 12 months
Inadequate Item 5 revenue reporting (NAICS + product/service code) 2024 form added product/service code overlay on top of NAICS Map revenue by both code systems before filing; confirm with finance team

Item 4 has been the single most contentious item under the new form. The expansion of Item 4 to include ordinary-course projections means that buyer board decks, internal budget presentations, and strategic-plan PowerPoints from the prior 12 months may all be responsive. Pre-filing document collection is now a serious exercise, not a same-week scramble. Major firm guidance on the new Item 4 has been published by Simpson Thacher, Debevoise & Plimpton, and Freshfields, with most concluding that the document burden under the new form is at least double the old form.

Private actions: Clayton Act Section 16 and state AG suits

HSR clearance does not preclude private antitrust litigation. Under Section 16 of the Clayton Act (15 U.S.C. 26), private parties and state attorneys general can sue to enjoin a merger even after HSR clearance. The Kroger-Albertsons matter is the clearest recent example: the FTC sued in federal court while the Washington and Colorado state attorneys general sued separately in state court, with the Washington case (King County Superior Court) producing the final blocking order in December 2024. State AGs frequently coordinate with federal regulators under the National Association of Attorneys General antitrust task force, but they can and do act independently when their state’s residents are particularly affected.

Private plaintiffs can also sue under Section 16 to enjoin a closing or under Section 4 of the Clayton Act for treble damages post-closing. Treble damages exposure after closing is a continuing concern for buyers in concentrated industries, even where HSR cleared.

For deal structure decisions that affect HSR mechanics (such as asset sale versus stock sale structure and the resulting reportability analysis), the HSR analysis should run alongside tax structuring. Some asset-only transactions that would be reportable as stock deals can be partly de-reported through structure (selling out non-overlapping product lines first, for example). The material adverse effect clause in the purchase agreement should track HSR risk explicitly, including pull-and-refile mechanics. The purchase agreement negotiation should specify which party bears HSR risk if a Second Request issues, including the divestiture obligation cap (the so-called “antitrust efforts” clause).

TLDR: eight Hart-Scott-Rodino takeaways

Hart-Scott-Rodino is not a clerical exercise. The 2024-25 overhaul made the filing materially more burdensome, and the enforcement environment of 2024 produced more blocked deals than any year in recent memory. Buyers planning M&A activity in 2026 should run their HSR reportability and exemption analysis at the LOI stage, identify the UPE in writing, and budget for the new form’s expanded document and projection requirements. Sellers should pre-assemble HSR-responsive materials during sell-side prep so that the buyer’s filing timeline does not become the deal’s critical path.

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