Why Does the Government Regulate Business Mergers and Acquisitions (2026)

The short answer to why does the government regulate business mergers and acquisitions is that Congress decided in 1914, and again in 1976, that uncontested consolidation tends to raise prices, suppress wages, and choke off the kind of rivalry that keeps capitalism honest. In fiscal year 2025 the Federal Trade Commission and the Department of Justice Antitrust Division reviewed 1,839 reportable deals under the Hart-Scott-Rodino Act, opened second-request investigations in 47 of them, and either blocked, conditioned, or forced the abandonment of transactions worth more than $310 billion in combined enterprise value (FTC HSR Annual Report FY2025; DOJ Antitrust Division Workload Statistics FY2025). For business owners contemplating a sale at the upper end of the middle market, antitrust review is no longer a footnote. It is a gating event.

What This Actually Means

Antitrust review is the federal government’s pre-clearance system for transactions large enough to reshape a market. Two statutes do the heavy lifting. The Clayton Act of 1914, as amended, prohibits any acquisition of stock or assets where “the effect of such acquisition may be substantially to lessen competition, or to tend to create a monopoly” (15 U.S.C. section 18). The Hart-Scott-Rodino Antitrust Improvements Act of 1976 turned that prohibition from a post-hoc enforcement tool into a pre-merger notification regime: parties to qualifying transactions must file with the FTC and DOJ and wait out a statutory review period before they can close (15 U.S.C. section 18a).

The practical effect is that any deal above a dollar-value trigger pauses for a federal review window. For 2026 the FTC set the size-of-transaction threshold at $126.4 million (FTC Premerger Notification Office, “Revised Jurisdictional Thresholds for Section 7A of the Clayton Act,” 19 Fed. Reg., January 2026). Below that line, deals close without notice. Above it, the parties file Form HSR, pay a filing fee, and wait. The minimum filing fee in 2026 is $30,000 for transactions between $126.4 million and $179.4 million, scaling up to $2.39 million for transactions valued above $5.508 billion (FTC 2026 fee schedule).

Most deals clear in 30 days. A small minority do not. The ones that do not are the ones that change industries.

The Six Things You Need to Understand About Why the Government Reviews Deals

The Consumer-Welfare Rationale and Its 2023 Update

From the late 1970s through 2022, federal merger review operated on a single yardstick: would the deal raise prices for consumers. That framework, often called the consumer-welfare standard, traced back to Robert Bork’s 1978 book and a generation of Chicago-school economics inside the agencies. If the merging firms could not raise prices post-close, the deal cleared.

The 2023 Merger Guidelines, issued jointly by the FTC and DOJ in December 2023, broadened that yardstick. The current standard still asks about price effects, but it also asks whether a deal will reduce the wages or working conditions of employees (labor monopsony), eliminate a potential competitor (potential-competition doctrine), entrench a dominant platform, or facilitate a serial-acquisition rollup that the agencies would have blocked if presented as a single transaction (2023 Merger Guidelines, Guidelines 6, 7, 8, and 9). The shift matters because deals that would have cleared under the older framework, especially in healthcare staffing, agricultural processing, and digital platforms, now face real scrutiny.

The HSR Pre-Notification Process

The HSR mechanic is straightforward in concept and grueling in execution. The acquiring person and the acquired person each file an HSR notification with the FTC’s Premerger Notification Office and the DOJ’s Antitrust Division. The 2024 redesign of the HSR Form, which took effect February 10, 2025, dramatically expanded what filers must produce. The new form requires narrative descriptions of competitive overlaps, a list of supply relationships between the parties, organization charts identifying officers and directors with horizontal positions in competitors, and submission of certain ordinary-course documents that discuss the transaction’s competitive rationale (FTC Final Rule, “Premerger Notification; Reporting and Waiting Period Requirements,” 89 Fed. Reg. 89216, November 2024). The FTC estimated the average filing burden rose from 37 hours under the old form to roughly 105 hours under the new one.

Once filed, the statutory waiting period is 30 days for most transactions and 15 days for cash tender offers and bankruptcy 363 sales. If neither agency requests more information, the parties can close on day 31. If an agency issues a “second request,” the clock pauses, and the parties must produce a comprehensive document and data response. The second request is the moment a deal becomes a project: production typically runs three to nine months, costs $5 million to $50 million in legal and economic-expert fees, and generates millions of documents.

The Substantive Standard: Substantially Lessen Competition

Whether a deal clears, settles, or gets blocked turns on Clayton Act Section 7’s “substantially lessen competition” test. Courts and the agencies operationalize that test through market definition, concentration measurement, and a counterfactual analysis of what the market looks like without the deal.

Market definition typically uses the hypothetical-monopolist test: would a hypothetical single firm controlling all output of the candidate market profitably impose a small but significant non-transitory increase in price (SSNIP), usually 5 percent. If yes, the candidate market is a relevant antitrust market. Concentration is then measured using the Herfindahl-Hirschman Index (HHI), the sum of the squared market shares of all firms. Under the 2023 Guidelines, a post-merger HHI above 1,800 combined with a delta above 100 creates a structural presumption of illegality (2023 Merger Guidelines, Guideline 1). That presumption can be rebutted, but the burden shifts hard to the merging parties.

Horizontal, Vertical, and Conglomerate Analysis

The agencies analyze three deal geometries differently. A horizontal merger combines direct competitors and gets the closest scrutiny because the unilateral price effect is immediate. Most of the headline cases below are horizontal. A vertical merger combines a supplier and a customer; the theory of harm is input foreclosure or customer foreclosure, where the merged firm starves rivals of a critical input or downstream channel. The 2020 Vertical Merger Guidelines were withdrawn in 2021, and the 2023 Guidelines treat vertical deals under Guideline 5, which asks whether the deal would foreclose rivals from access to a needed input or output.

Conglomerate deals combine firms in unrelated markets. Historically these cleared without issue. The 2023 Guidelines do not have a dedicated conglomerate guideline, but Guideline 7 on entrenchment of dominant positions and Guideline 8 on serial acquisitions can reach conglomerate deals where one party has market power that the acquisition would protect or extend.

The 2023 Guidelines Reset: Labor, Platforms, Serial Acquisitions

Three pieces of the 2023 Guidelines deserve specific attention from sellers. First, Guideline 10 codified labor-market monopsony as an independent theory of harm. A deal that combines the two largest employers of nurses, truck drivers, or warehouse workers in a metro area can be challenged on labor grounds even if consumer prices would not move. The DOJ has cited Guideline 10 in at least three 2024-2025 investigations of healthcare-staffing roll-ups (DOJ Antitrust Division, “Year in Review 2024”).

Second, Guideline 9 on minority and partial ownership treats non-controlling investments as potentially reportable if they convey board representation, information rights, or contractual veto rights over competitive decisions. Private-equity fund-of-funds structures and common ownership across portfolio companies are squarely in scope.

Third, Guideline 8 on serial acquisitions allows the agencies to aggregate a sequence of small deals by the same acquirer in the same market and challenge them as a single course of conduct. The 2024 FTC complaint against U.S. Anesthesia Partners, alleging a multi-year roll-up of anesthesiology practices in Texas, was the first major test of this guideline (FTC v. U.S. Anesthesia Partners, Inc., S.D. Tex., complaint filed September 2023; pending as of FY2026).

State, EU, UK, and China Overlap

Federal HSR review is not the only filter. Thirty-eight state attorneys general have antitrust authority and routinely review deals affecting their states; California, New York, Texas, and Washington are the most active. The European Union’s merger regulation, Council Regulation (EC) No 139/2004, requires notification to the European Commission for deals with a combined worldwide turnover above 5 billion euros and EU-wide turnover above 250 million euros for each of at least two parties (EU Merger Regulation, Article 1). The United Kingdom’s Competition and Markets Authority operates a voluntary but de facto mandatory regime; the CMA’s 2025 merger guidance updated its jurisdictional reach to deals with a UK turnover of either party above 100 million pounds (CMA, “Mergers: Guidance on the CMA’s jurisdiction and procedure,” updated 2025). China’s State Administration for Market Regulation (SAMR) reviews deals where the parties have combined global turnover above 12 billion RMB and Chinese turnover above 800 million RMB for at least two parties.

Practical consequence: a transatlantic technology deal of meaningful size typically files in the United States, the EU, the UK, and often Brazil, Canada, India, Japan, Korea, and China. Each regulator runs its own timetable. The longest timetable usually controls the closing date.

Worked Example: Reading an HSR Exposure on a $300M Specialty Manufacturer

Consider Apex Specialty Coatings, a fictional but realistic Ohio-based maker of corrosion-resistant industrial coatings with $185 million in revenue and $42 million of EBITDA. The owner is contemplating a sale at a 7.5x EBITDA multiple, implying $315 million enterprise value. Three bidders surface. Bidder A is a strategic competitor with $740 million of revenue in the same product category and an estimated 22 percent national market share. Bidder B is a financial sponsor with no portfolio overlap. Bidder C is a foreign chemical conglomerate with no U.S. coatings exposure but a Chinese parent.

The transaction value of $315 million sits well above the 2026 HSR threshold of $126.4 million, so all three bidders trigger HSR. Filing fee at $315M lands in the $179.4M-$555.5M tier at $105,000 (FTC 2026 fee schedule). But the substantive review profiles diverge sharply.

For Bidder A, the combined market share would approach 35 percent and the HHI delta likely exceeds 200. A second request is highly probable. Expected legal and economic fees through resolution range from $8 million to $22 million. Likely outcome: divestiture of two plants to a third-party buyer as a condition of clearance, with a six- to twelve-month delay from signing to close. Apex should price a second-request risk premium into Bidder A’s offer of roughly 0.4x to 0.7x EBITDA.

For Bidder B, the financial sponsor, the deal is reportable but should clear at the end of the initial 30-day waiting period without issue. The only complication is whether the sponsor has portfolio overlap; HSR Form Item 6(c)(ii) now requires disclosure of officer and director overlaps across portfolio companies. A clean financial bidder is the lowest-friction path to close.

For Bidder C, the Chinese-owned bidder, HSR review proceeds in parallel with a Committee on Foreign Investment in the United States (CFIUS) filing. CFIUS is separate from antitrust but lives in the same closing-condition stack. A specialty-coatings business with defense-adjacent end uses, for example aerospace fasteners, is likely to draw a CFIUS investigation, adding 45 to 90 days and the real possibility of a mitigation agreement or prohibition.

The seller-side lesson: bidder identity changes the deal calendar more than bidder price. A $315M offer that closes in 60 days is materially better than a $335M offer that closes in 14 months with a 20 percent break-fee risk.

Recent Enforcement: What Got Blocked, Settled, and Cleared

Six transactions from 2021 through 2025 illustrate the live envelope of federal merger enforcement.

Microsoft-Activision Blizzard: Cleared with Behavioral Conditions ($68.7B, 2023-2024)

Microsoft’s acquisition of Activision Blizzard was the largest video-game deal in history. The FTC sued in December 2022 to block it (In re Microsoft Corp. and Activision Blizzard, Inc., FTC Docket No. 9412). The agency’s theory was vertical: Microsoft, as owner of the Xbox console and Game Pass subscription, would have an incentive to withhold Call of Duty and other Activision content from Sony’s PlayStation and Nintendo Switch. The U.K. CMA initially blocked the deal in April 2023, then accepted a restructured remedy in October 2023 under which Microsoft divested cloud-streaming rights for Activision games to Ubisoft outside the European Economic Area. The European Commission cleared with commitments. The FTC’s in-house challenge continued but lost a preliminary-injunction motion in the Northern District of California in July 2023 (FTC v. Microsoft Corp., 681 F. Supp. 3d 1069 (N.D. Cal. 2023)). The deal closed October 13, 2023. The FTC’s administrative case dismissed in May 2024 (FTC Final Order, May 2024).

Adobe-Figma: Abandoned ($20B, 2022-2023)

Adobe announced the acquisition of design software upstart Figma in September 2022. The EU Commission opened a Phase II investigation in August 2023, and the U.K. CMA issued provisional findings in November 2023 that the deal would substantially lessen competition in interactive product-design software, vector-editing tools, and raster-editing tools. DOJ was preparing a complaint. On December 18, 2023, Adobe and Figma announced abandonment, with Adobe paying a $1 billion termination fee. Public statement from Adobe CEO Shantanu Narayen cited “no clear path to receive necessary regulatory approvals” (Adobe press release, December 18, 2023). Adobe-Figma is the canonical recent example of regulatory deterrence forcing abandonment before a court ruling.

JetBlue-Spirit: Blocked at Trial ($3.8B, 2022-2024)

The DOJ sued to block JetBlue’s acquisition of Spirit Airlines in March 2023. The case went to trial in October-December 2023 before Judge William Young in the District of Massachusetts. On January 16, 2024, Judge Young blocked the deal, ruling that the elimination of Spirit, the largest ultra-low-cost carrier in the United States, would harm price-sensitive flyers and consolidate the U.S. airline industry from four to three major low-fare options (United States v. JetBlue Airways Corp., 712 F. Supp. 3d 109 (D. Mass. 2024)). JetBlue and Spirit abandoned the merger on March 4, 2024. Spirit filed for Chapter 11 bankruptcy in November 2024.

Kroger-Albertsons: Blocked ($24.6B, 2022-2024)

The FTC sued in February 2024 to block Kroger’s acquisition of Albertsons, the second-largest U.S. supermarket deal ever. The trial ran in August-September 2024 in the District of Oregon before Judge Adrienne Nelson, who issued a preliminary injunction on December 10, 2024 (FTC v. Kroger Co., 766 F. Supp. 3d 1119 (D. Or. 2024)). The Washington state superior court also enjoined the deal. Kroger and Albertsons terminated the merger on December 11, 2024, and immediately filed cross-suits over the $600 million termination fee. The case is notable for the FTC’s heavy emphasis on Guideline 10 labor-monopsony theory: union-grocery workers were a defined relevant market for harm.

Aon-Willis Towers Watson: Abandoned ($30B, 2020-2021)

The DOJ filed suit in June 2021 to block Aon’s acquisition of Willis Towers Watson. The agency’s complaint focused on the combination of the second- and third-largest insurance brokers serving Fortune 1000 clients in commercial risk brokerage, reinsurance, and retirement consulting (United States v. Aon plc, D.D.C., filed June 16, 2021). Aon and WTW abandoned on July 26, 2021, with Aon paying a $1 billion termination fee. The DOJ’s complaint, drafted under outgoing Trump-era and incoming Biden-era leadership, demonstrated continuity of horizontal-merger enforcement across administrations.

Capital One-Discover: Cleared ($35.3B, 2024-2025)

Capital One announced the acquisition of Discover Financial Services in February 2024. The deal combined the largest U.S. credit-card issuer (by purchase volume after the deal) with the smaller of the two U.S.-headquartered payment networks. The DOJ Antitrust Division and the Federal Reserve, along with the Office of the Comptroller of the Currency, conducted parallel reviews. After a 14-month process, the Federal Reserve and OCC approved on April 18, 2025, and the DOJ declined to challenge (Federal Reserve Board, Order Approving the Acquisition of a Savings and Loan Holding Company, April 2025). The deal closed May 18, 2025. The clearance was widely read as a signal that vertical and conglomerate financial-services combinations can still secure approval where the parties make credible competitive commitments around interchange and network access.

Common Mistakes Sellers Make on Antitrust Exposure

Treating HSR as a Buyer Problem

Sellers often assume HSR risk lives entirely on the buyer’s side of the table. It does not. The seller’s deal value is at risk during the entire review period, the seller bears half the break-fee economics in most merger agreements, and the seller’s operating business suffers from prolonged uncertainty. A seller who does not understand the antitrust profile of each bidder is negotiating blind.

Ignoring State Attorneys General

The Kroger-Albertsons deal was actually killed by parallel state actions in Washington and Colorado before the federal preliminary injunction issued. Healthcare, grocery, and gas-station deals routinely draw state-level scrutiny that federal counsel underweights. A seller in a regulated industry should ask buyer counsel for a written state-by-state exposure analysis as part of due diligence.

Underestimating the New HSR Form Burden

Filings under the post-February 2025 HSR Form take three to four times longer to prepare. Deals signed in 2024 under the old form’s regime are not a useful precedent. The cost of even an uncontested filing is now meaningful, and the disclosure of “transaction-related documents” reaches drafts, board decks, and the kind of competitive-rationale slides that look damning out of context. Sellers should run a document-hygiene review of any deal-related materials they generate during a sale process.

Not Pricing the Antitrust Premium into Bid Selection

A strategic bidder almost always pays more than a financial bidder because of synergies. But the higher price compensates for antitrust risk only if the seller actually receives it. A seller should compare bids on a risk-adjusted basis: expected price times probability of close. A 7.5x EBITDA strategic bid with a 70 percent probability of clearing in twelve months can be worse than a 6.8x financial bid that closes in sixty days.

Confusing Settlement with Clearance

When the agencies “settle” a deal with a consent decree, the parties almost always agree to divestitures, behavioral commitments, or both. Divestitures destroy value. A buyer that quietly accepts a divestiture remedy is paying less for less, and the seller’s earn-out or rollover stake gets affected accordingly. The deal-points term sheet should specify who bears the value loss of mandated divestitures.

Skipping Antitrust Review on Roll-Up Add-Ons

Private-equity sponsors running a roll-up strategy often treat add-on acquisitions as too small to file. Many add-ons do fall below the HSR threshold, but Guideline 8 of the 2023 Merger Guidelines allows the agencies to aggregate them. A platform plus six add-ons that, taken together, would have triggered HSR can now be investigated retrospectively. The U.S. Anesthesia Partners case is the warning shot.

Timeline: From Signed LOI to Closed Deal Under HSR Review

For a reportable transaction in the $200M to $500M enterprise-value range, the federal-review calendar typically runs as follows.

Weeks 1-4 after signed LOI: Antitrust counsel onboarded by both parties. HSR strategy memo drafted. Preliminary competitive overlap analysis. Document holds issued for “ordinary course documents” and “transaction-related documents.”

Weeks 4-10: HSR Form preparation. The new HSR Form requires narrative descriptions of overlaps, supply relationships, and minority-investment relationships. Document collection and review for Items 4(c) and 4(d) typically runs concurrently. Filing fee paid.

Day of filing (target): signing date or 1-3 days after. Both parties file. Statutory 30-day waiting period begins.

Day 30: Initial waiting period expires. For roughly 96 percent of filings in FY2025, the deal can close. The remaining 4 percent receive a second request (FTC HSR Annual Report FY2025).

Second request: months 1-9 after issuance. Document and data production. Custodian interviews. Economic-expert work. Investigational hearings (depositions under oath). Substantial compliance is certified by the parties when the agency confirms it has what it needs. A second waiting period of 30 days runs from substantial compliance.

End of second waiting period: Agency either closes the investigation (clearance), enters a consent decree (settlement with divestitures or behavioral commitments), or files a complaint to enjoin (challenge). Challenge cases proceed to court, where preliminary-injunction trials typically run 8 to 14 weeks.

Total elapsed time from signing to close: 30 days for uncontested deals, 9 to 14 months for second-request deals that settle, 12 to 24 months for litigated deals that ultimately clear, and 14 to 28 months for litigated deals that are abandoned. Abandonment is a real and increasingly common outcome.

Frequently Asked Questions

What is the 2026 HSR threshold for filing a notification?

The 2026 size-of-transaction threshold is $126.4 million, adjusted annually by the FTC based on changes in U.S. gross national product (FTC Premerger Notification Office, January 2026 Federal Register notice). Below that, no HSR filing is required regardless of the parties’ size. Above that, the filing is mandatory and waiting periods apply. The size-of-person test, which can pull in deals between $126.4M and $505.8M based on the parties’ asset and revenue size, also applies.

Can a small business sale ever face antitrust review?

Not under federal HSR if it falls below the threshold. But the substantive Clayton Act Section 7 prohibition has no dollar floor: the agencies and private plaintiffs can challenge any acquisition, regardless of size, that substantially lessens competition. Sub-threshold healthcare and pharmacy roll-ups have drawn FTC enforcement under Guideline 8. State attorneys general also operate without a federal-dollar floor.

How long does a second request actually take?

Median time from second-request issuance to substantial compliance was 5.8 months in FY2025 (DOJ Antitrust Division Workload Statistics). Add a 30-day second waiting period, plus litigation if the deal is challenged. Total post-second-request elapsed time of 8 to 18 months is normal. Litigated cases like Kroger-Albertsons can run 22 to 26 months from signing to abandonment.

What is the difference between a behavioral remedy and a structural remedy?

A structural remedy requires divestiture: the merged firm sells assets to a third party to restore competition. A behavioral remedy imposes conduct rules: the merged firm commits to license a product on fair terms, separate certain operations, or accept ongoing compliance monitoring. The DOJ has stated since 2021 that it strongly prefers structural over behavioral remedies (DOJ Antitrust Division Manual; AAG remarks on remedies, 2021-2024). Behavioral remedies remain more common in vertical deals like Microsoft-Activision.

Do European or U.K. authorities care about a U.S.-only deal?

Generally no, unless the target has meaningful EU or U.K. revenue, supplies into those markets, or holds intellectual property licensed there. The EU Merger Regulation requires Community-dimension turnover thresholds to be met. The U.K. CMA can assert jurisdiction over deals affecting a substantial share of supply in the U.K., a flexible test that has reached transactions without a U.K. legal entity on either side. A purely domestic U.S. deal with no EU or U.K. revenue typically does not require foreign filings.

What is the failing-firm defense and does it work?

The failing-firm defense allows an otherwise anticompetitive merger to clear if the target would imminently fail, has no less-anticompetitive alternative buyer, and would exit the market with its assets sold off in bankruptcy absent the deal. The 2023 Guidelines preserve the defense but apply it strictly. The defense is occasionally successful in distressed healthcare and newspaper transactions. It almost never succeeds in deals where the target is solvent but underperforming.

What to Do Next

The seller’s job during an antitrust-exposed sale is to make the buyer’s path to close as short and predictable as possible, then to extract value for that predictability in the deal terms. That means three things. First, run an antitrust pre-screen at the LOI stage, before the seller’s auction calendar locks in. Second, write the merger agreement with sharp regulatory-efforts covenants, divestiture obligations, and a meaningful reverse termination fee. Third, manage the document trail during diligence as if every email will be produced to the FTC, because in a second request it will be.

CT Acquisitions runs the buy side of middle-market transactions. We see the antitrust calendar from the perspective of the party that has to file the form, sit for the deposition, and write the check for the divested plant. That is why we screen for regulatory exposure before we ever take a deal to market, and why we counsel sellers on bidder selection in terms of risk-adjusted value, not headline price. Buyers pay us, not sellers, so our incentive is to close clean deals, not to chase the highest-quoted multiple to a deal that dies in second request.