The 2026 HSR Threshold Is $133.9 Million. Why Antitrust Keeps Showing Up in BigLaw

For 2026, the minimum HSR size-of-transaction threshold is $133.9 million.

That number comes from the FTC's January 2026 HSR threshold announcement, which raised the threshold from $126.4 million to $133.9 million. The filing rules are more complicated than one number, but students do not need to memorize the whole fee schedule to understand why antitrust is such a major BigLaw practice.

The point is this: once companies start buying each other at meaningful scale, antitrust lawyers enter the deal.

What HSR means

HSR stands for Hart-Scott-Rodino. It is the premerger notification regime that requires certain transactions to be reported to the federal antitrust agencies before closing.

If a transaction is reportable, the parties generally have to file, wait, and give the agencies time to review whether the deal may harm competition. The rules turn on transaction value, party size, exemptions, and timing.

As a junior associate, you are not setting antitrust policy on day one. You may be helping collect information, draft filing materials, review documents, track timing, or coordinate with corporate deal teams.

That is why antitrust can feel both regulatory and transactional.

Why the threshold changes

The FTC says HSR jurisdictional thresholds are revised annually based on the change in gross national product. Filing fee thresholds also adjust under the statutory fee framework.

For students, the annual adjustment is a reminder that this is a live regulatory system. Antitrust lawyers are not only reading old cases. They are tracking agency rules, filing requirements, enforcement priorities, and deal timing.

If you like law plus markets plus strategy, antitrust is worth understanding.

The merger guidelines matter too

The HSR threshold tells you when some deals must be reported. It does not tell you how the agencies will analyze competition.

For that, start with the DOJ and FTC's 2023 Merger Guidelines. The agencies describe the guidelines as a statement of factors and frameworks they often use when reviewing mergers and acquisitions. The guidelines are not themselves binding law, but they tell lawyers how the agencies are thinking.

That matters in practice. If a deal raises horizontal concentration, potential competition, vertical foreclosure, labor-market, platform, or serial-acquisition concerns, antitrust lawyers have to assess the risk early.

What antitrust associates actually do

Junior antitrust work can include:

• Researching agency precedent
• Helping draft HSR filings
• Reviewing ordinary-course business documents
• Preparing second request responses
• Building chronologies
• Coordinating with economists
• Tracking competitor and customer issues
• Supporting merger-risk memos
• Helping litigation teams if the government challenges a deal

The work can be document-heavy. It can also be intellectually interesting because you are asking how a market works.

Who competes with whom? What do customers substitute when prices rise? Does a company have market power? Is a new entrant realistic? Does the deal remove a future competitor?

Those are business questions and legal questions at the same time.

Why BigLaw needs antitrust lawyers

Antitrust sits near the center of major M&A. A deal can have perfect corporate documents and still fail if the regulatory risk is too high.

That makes antitrust lawyers valuable to deal teams. They help decide whether a client should sign, how much antitrust risk the buyer should accept, what covenants belong in the merger agreement, and how long the parties should expect review to take.

In contested matters, antitrust lawyers may also litigate against the government or private plaintiffs.

How to talk about antitrust in interviews

Do not say only, "I like regulation."

Be more specific:

• "I am interested in how merger review affects deal timing."
• "I like the mix of economics, litigation risk, and transactional strategy."
• "I have been reading about the HSR thresholds and wanted to understand how juniors help on filings."
• "I am curious how the 2023 Merger Guidelines changed the way the group advises deal teams."

That shows you have done enough homework to understand the practice.

You do not need to be an economist. You do need to be curious about how companies compete.