Mergers & Acquisitions: Antitrust and HSR

Merger antitrust counsel from lawyers who have run the process from every seat — in-house, at the DOJ, a state attorney general's office, and the European Commission, and across the table from the agencies.

Most deals do not have an antitrust problem. The ones that do rarely announce themselves — and the cost of finding out late is measured in months of delay, seven-figure penalties, or a deal that dies in review. Even the deals with no substantive antitrust problems might require filings before closing. Bona Law advises buyers, sellers, boards, and investors at every stage of the merger process: assessing antitrust risk before the letter of intent, preparing and filing Hart-Scott-Rodino premerger notifications, coordinating merger-control filings worldwide, negotiating with the FTC, DOJ, and state attorneys general, responding to second requests, and structuring remedies when a deal needs them.

We are an antitrust boutique, not deal counsel — and that is the point. Excellent corporate firms handle the transaction; we integrate into their deal teams to handle the competition issues, without overlap, turf friction, or BigLaw overhead. Corporate law firms without antitrust practice groups regularly retain Bona Law to handle HSR filings and merger antitrust strategy for their clients' deals, and private equity firms rely on us across their portfolios — from fund-structure reportability analysis to add-on acquisitions.

Our merger team has run this process from every seat. Steve Cernak spent more than twenty years as in-house antitrust counsel at General Motors, where he led merger reviews and filed hundreds of HSR notifications. Luis Blanquez served on the European Commission's Merger Task Force, working on landmark reviews including Oracle/PeopleSoft. Paul Moore investigated corporate conduct and more than one hundred proposed merger transactions at the Department of Justice and, as a California enforcer, was lead attorney for California in the successful joint challenge, with the FTC and the District of Columbia, to the proposed DraftKings/FanDuel merger, and lead attorney in the government's successful federal-court challenge to the Valero/Plains All American merger. And Kristen Harris represents companies and individuals in merger reviews and investigations before the DOJ, the FTC, and foreign competition authorities, and she first saw merger review from the inside as a law clerk in the FTC's Bureau of Competition. When your deal meets the government, we know what the people on the other side of the table are thinking — because we have been them.

What We Do

Pre-deal antitrust risk assessment — merger feasibility analysis, market-definition and competitive-effects review, and frank early advice on whether a deal will draw scrutiny, so you can price antitrust risk before you sign, not after.
Hart-Scott-Rodino filings — reportability analysis (including exemptions and aggregation traps), preparation and filing of HSR notifications, filing-fee questions, and management of the waiting period. We track the HSR rules as they change — including the 2026 litigation that vacated the expanded HSR form and returned filers to the prior form — so your filing is built for the rules actually in effect.
HSR filings for other law firms — corporate and deal firms without antitrust practice groups engage us to handle their clients' HSR filings and antitrust risk. See HSR and Merger Counsel for Law Firms below.
Private equity transactions — fund and ultimate-parent-entity analysis, aggregation across funds and portfolio companies, add-on strategy, and interlocking-directorate compliance for sponsor board seats.
Second requests — strategy to head off or narrow a second request, and negotiation and management of compliance when one issues, informed by lawyers who have negotiated them with the agencies rather than merely processed documents. With our in-house document production expertise and full complement of attorneys at all levels, we can handle any necessary large document productions.
Global merger control — coordination of multi-jurisdictional filings with the European Commission, the UK CMA, and other authorities worldwide, drawing on direct ex-Commission experience and our international competition practice.
State premerger notification and state AG review — the new state filing regimes, including California's Uniform Antitrust Premerger Notification Act (effective January 1, 2027), and merger investigations by state attorneys general — an increasingly active front we know from the enforcement side.
Gun-jumping and information exchange — what buyers and sellers may share and coordinate during diligence, negotiation, and pre-closing integration planning. The agencies have imposed record gun-jumping penalties; the rules are manageable with counsel and expensive without it.
Remedies, consent decrees, and Tunney Act proceedings — structural and behavioral remedy design and negotiation, and federal-court proceedings to secure final approval of merger settlements with the government.
Joint ventures and other collaborations — antitrust structuring, HSR analysis, and ongoing counsel for joint ventures, marketing and distribution alliances, and industry collaborations, including long-term service as outside antitrust counsel to ventures among competitors.
Third-party submissions — representing customers, competitors, and other third parties who want to raise concerns about a proposed merger with federal or state agencies, publicly or confidentially, and defending third-party subpoenas and CIDs in merger investigations.
Non-reportable, structured, and closed deals — antitrust risk counseling for transactions below the HSR thresholds (which agencies and state AGs can still challenge), avoidance-device analysis under HSR Rule 801.90 — where structuring around the threshold just produced a record $12 million penalty — post-closing investigations, and Section 8 interlocking-directorate compliance.

Deal risk is often industry-specific. For energy transactions with parallel FERC review, agriculture and food deals, technology and platform acquisitions, and blockchain and digital-asset deals, see our Energy and Commodities Trading, Agriculture and Food, Telecommunications and Platforms, and Blockchain and Bitcoin industry pages.

HSR and Merger Counsel for Law Firms

A large share of our merger work comes to us from other law firms. Excellent corporate, M&A, and deal firms regularly reach the same moment: the deal needs an HSR filing — or an antitrust risk answer — and the firm does not have an antitrust practice group. Bona Law is built for that call. We handle the reportability analysis, prepare and make the filing, manage the waiting period and any agency questions, and hand the client back. Because we are an antitrust boutique with no corporate transactions practice, there is nothing else for us to take: referring firms keep the client, the deal, and the relationship.

We integrate into your deal team at whatever level the transaction needs — from a same-week, low-fee filing on a no-overlap deal to full clearance strategy on a contested one. Deal lawyers who have worked with us once tend to call us on every deal that crosses the threshold. Learn more about how we work with other firms on our Antitrust Co-Counsel page, or contact us about a pending transaction.

Private Equity and Serial Acquirers

Private equity deals raise HSR questions that ordinary corporate transactions do not: which fund is the ultimate parent entity, how holdings aggregate across funds and portfolio companies, when management rollovers and side investments count toward the transaction size, and how sponsor board seats interact with Section 8's interlocking-directorate rules. We answer these questions for sponsors and their portfolio companies deal after deal — including add-on programs, where serial acquisitions in concentrated markets draw agency attention even when each deal is individually non-reportable, and where a structure chosen to stay under the threshold can itself become the violation under Rule 801.90. For funds and their deal counsel, we function as an on-call HSR/antitrust desk: quick reportability answers, predictable reasonable fees on routine filings, and senior attention when a deal has substance to it.

Representative Experience

A selection of Bona Law's merger and transaction matters. Most merger-clearance clients are confidential, so descriptions are generalized.

U.S. and cross-border merger clearance across multiple transactions for corporate and private equity clients — including parallel HSR filings and coordinated competition filings before the European Commission, the UK CMA, and other non-U.S. authorities, with second-request response experience.
Antitrust counseling on strategic acquisitions across multiple industries, for clients ranging from startups to Fortune 100 companies — pre-deal risk assessment, HSR notification strategy, market-definition analysis, and remedy negotiation.
HSR filings and merger antitrust counsel handled for the clients of corporate law firms without antitrust practice groups, integrating into the referring firm's deal team.
Negotiation and ongoing antitrust counsel for joint ventures among automotive and other rivals, including serving as virtual general counsel to a joint venture among competitors for more than a decade.
Illumina-Grail merger review: amicus brief on behalf of a bipartisan group of 34 Members of Congress addressing the FTC's authority and the appropriate antitrust standard — in one of the defining merger cases of the decade.
Disney/FuboTV sports-streaming joint venture: amicus brief in the Second Circuit on behalf of leading antitrust law professors addressing the standard for new entry into concentrated streaming markets.
Representation of a trade association in litigation that included opposing a proposed anticompetitive merger of regional real-estate MLS providers — experience on the objector's side of merger review.
Interactions with and submissions to enforcement agencies for various clients as they provide information to help enforcers evaluate mergers of their competitors, suppliers, or customers.

The HSR Process, Handled

Hart-Scott-Rodino looks like a form and behaves like a process. Whether a deal is reportable turns on thresholds that adjust every year (the size-of-transaction floor is $133.9 million for 2026), exemptions, and aggregation rules that regularly trap sophisticated parties — and the penalty for getting it wrong now exceeds $53,000 per day, with the agencies imposing a record $12 million in failure-to-file penalties in July 2026 against parties who structured around the threshold. The filing itself has been a moving target: an expanded HSR form took effect in February 2025, a federal court vacated it in February 2026, and filers are back on the prior form while the agencies work on a replacement. We track every step of this — our attorneys' HSR analysis is read by practitioners and enforcers worldwide on The Antitrust Attorney Blog — and our team members have run the process itself hundreds of times, from routine no-issue filings to multinational reviews.

Why Bona Law for Merger Antitrust

We have sat in every seat. In-house at General Motors running global merger reviews; inside the European Commission's Merger Task Force; at the DOJ and a state attorney general's office investigating and challenging deals; and across the table from the FTC and DOJ in merger reviews and second requests. Your deal gets judged by agencies — we know how they think.
We complement your deal counsel, not compete with them. Bona Law has no corporate transactions practice. Deal firms refer us their HSR filings and antitrust issues precisely because we integrate into their teams and hand the client back.
Enforcement-side fluency, federal and state. Merger review is no longer just federal: state attorneys general investigate and sue, and states are adopting their own premerger-notification laws. Our State Attorney General Antitrust practice includes the partner who led the government's successful vertical merger challenge in California v. Valero/Plains All American and served as California’s lead attorney in the joint federal-state challenge that stopped the proposed DraftKings/FanDuel merger.
Litigation strength behind the counseling. If your deal is challenged — or you need to challenge someone else's — the same firm that files your HSR tries antitrust cases in federal courts nationwide.
Boutique economics. Senior specialists, predictable fees, and none of the leverage-model overhead. For most deals, merger antitrust is a scoped problem; we price it that way.

Frequently Asked Questions

Do we need to file HSR for our deal? It depends on the size of the transaction and, for mid-size deals, the size of the parties — the 2026 size-of-transaction threshold is $133.9 million — plus exemptions and aggregation rules that are easy to get wrong. Non-reportable deals can still be investigated and challenged. We give reportability answers quickly, usually on a fixed fee.

Can we structure the deal to stay under the HSR threshold? Not for the sole purpose of avoiding the filing. HSR Rule 801.90 disregards any transaction structure or device "employed for the purpose of avoiding" notification — the agencies look at the deal's substance, not its labels. In July 2026 the FTC collected a record $12 million in penalties from parties who priced an acquisition just under the threshold and paid the difference through a side investment. Structures with a real, independent business rationale are fine; we help you build and document that rationale.

How long does HSR review take? The initial waiting period is 30 days (15 for cash tender offers and certain bankruptcy sales). Most deals clear then. If an agency opens an in-depth review and issues a second request, the timeline extends to many months — one more reason to assess risk before signing.

What does an HSR filing cost? Government filing fees run from $35,000 to $2.46 million depending on deal size (2026 tiers). Legal fees depend on complexity: a no-overlap filing is a scoped, predictable project we can quote as a fixed fee; deals with substantive overlaps cost more because the strategy matters more. We tell you which one you have before we start. Either way, our reasonable fees reflect our low overhead.

Our firm doesn't have an antitrust practice — can Bona Law handle the HSR filing for our client's deal? Yes — this is a core part of our practice. Corporate and deal firms retain us to run the HSR analysis and filing for their clients, and we work within your deal team and timeline. We have no corporate practice, so your client relationship is never at risk. See HSR and Merger Counsel for Law Firms above.

How does HSR treat private equity funds? Reportability is analyzed at the fund's ultimate parent entity (which is uniquely defined under HSR rules), with aggregation rules that reach across the fund structure — and management rollovers, side investments, and contemporaneous payments can count toward the transaction size. Add-on programs raise their own issues, from serial-acquisition scrutiny to Section 8 board-seat interlocks. We do this analysis for sponsors on a deal-by-deal and portfolio basis.

What triggers a second request? Competitive overlaps, hot industries, complaining customers, and — sometimes — the parties' own documents. What your deal team writes down in board decks and emails shapes agency review more than almost anything else, which is why we get involved before the documents are created.

What is gun-jumping? Acting like one company before you legally are one — coordinating prices, swapping competitively sensitive data, or taking control before the waiting period ends. The agencies have imposed record penalties for it. Diligence and integration planning are lawful with the right protocols; we build them.

Do state governments review mergers too? Increasingly, yes. State attorneys general investigate and challenge deals — including deals federal agencies clear — and states are adopting their own premerger-notification requirements, including California's, which takes effect January 1, 2027. We counsel on state filing obligations and represent clients in state AG merger investigations.

Merger and HSR Resources

Selected practical guidance from The Antitrust Attorney Blog and Bona Law's resource library:

For private equity-specific analysis, see the blog's Private Equity category.

Our Merger Antitrust Team

Steve Cernak (Partner, Detroit). More than twenty years as in-house antitrust counsel at General Motors; led merger reviews and filed hundreds of HSR premerger notifications, negotiated and responded to second requests, and managed multinational merger reviews. The firm's HSR practice lead.
Luis Blanquez (Partner, San Diego). He is an international antitrust and competition law attorney with 15 years of experience at the European Commission and major international law firms. He currently is the Vice-Chair of the Media and Technology Committee of the American Bar Association Antitrust Section. Before moving to the United States in 2016, Luis served with the Merger Task Force, Directorate-General for Competition of the European Commission in Brussels, (DG Comp), where he investigated and analyzed numerous proposed mergers including: Oracle/Peoplesoft (phase II) , Banco Santander/Abbey, and EDP/GDP/ENI (phase II), among others.
Paul Moore (Partner, San Diego). Former California Senior Deputy Attorney General and DOJ Antitrust Division trial attorney; at DOJ he investigated corporate conduct and more than one hundred proposed merger transactions, and as a California enforcer he was lead attorney for California in the joint challenge by the FTC, California, and the District of Columbia that stopped the proposed DraftKings/FanDuel merger, and lead attorney in the government's successful federal-court challenge to the Valero/Plains All American merger; leads on state AG merger review and state premerger notification.
Kristen Harris (Of Counsel, San Diego). Represents companies and individuals before the DOJ, the FTC, and foreign competition authorities in merger reviews and civil and criminal investigations; clerked in the FTC's Bureau of Competition during law school, working on merger reviews and civil investigations, and served as a research assistant to a former FTC Commissioner. Counsel to the Chair of the ABA Antitrust Law Section.

When a deal draws litigation or enforcement, the merger team works alongside the rest of the firm — including our Antitrust Litigation, Investigations, and Antitrust Counseling and Compliance practices.

Contact Us

The best time to involve merger antitrust counsel is before the letter of intent — when risk can still shape price and structure. Whether you need a quick reportability answer, a full clearance strategy, help with a second request, an HSR filing for your law firm's client, or a way to object to someone else's deal.

Mergers & Acquisitions