Antitrust Merger Screener & Settlement Workbench

Benchmark:

Audit horizontal consolidation risks, calculate Herfindahl-Hirschman Index (HHI) changes, test state Attorney General lawsuit triggers, and design divestiture remedy settlements that resolve regulatory challenges.

Scenarios:

Market Participants 6 Firms

Select the acquiring firm and target firm, and adjust market shares.

Role	Firm Name	Share (%)

Primary Acquirer (Firm A)

Target Entity (Firm B)

State AG Settlement & Divestiture Remedy Apply Remedy

State AGs routinely condition merger clearance on spin-offs or asset carve-outs to preserve competitive pricing and local choices.

Carve-out / Divested Share: 3.0%

Divestiture Buyer (Independent Competitor)

Total market share represented:

Regulatory Risk Analysis 2023 Guidelines

Mathematical audit of structural presumptions and antitrust challenge probability.

Pre-Merger HHI

1,682

Moderate Concentration

Post-Merger HHI
2,074
Highly Concentrated

HHI Increase (ΔHHI)

+392

Exceeds 100 threshold

Combined Entity Share

CR4 (Top 4 Concentration)

76.0%

Oligopolistic coordination risk

Clayton Act Injunction Risk

88%

Requires AG Settlement

Market Concentration Spectrum HHI Scale: 0 to 4,000+

Post: 2,074

Unconcentrated (< 1,000) Moderate (1,000 – 1,800) Highly Concentrated (> 1,800)

Post-Transaction Market Distribution Simulated post-closing shares

Ready. Adjust shares or test settlement divestitures.

Antitrust Economics & State AG Settlement Mechanics

How federal antitrust authorities (DOJ/FTC) and State Attorneys General evaluate horizontal mergers under Section 7 of the Clayton Act and Supreme Court precedents like United States v. Philadelphia National Bank.

The 2023 Merger Guidelines Shift

In December 2023, the FTC and DOJ revised horizontal merger enforcement to return to historical statutory standards.

Concentration Threshold: Post-merger HHI > 1,800 with ΔHHI > 100 creates a presumption of illegality (tightened from 2010's 2,500 HHI / 200 Δ threshold).
30% Dominant Share Rule: A merged firm capturing >30% of a relevant antitrust market combined with ΔHHI > 100 is independently presumed anti-competitive.
Labor & Submarket Scrutiny: Examines regional buyer monopsony and multi-sided platform lock-in.

State Attorney General Standing

Under Section 16 of the Clayton Act (15 U.S.C. § 26), state AGs hold independent antitrust enforcement authority as parens patriae on behalf of citizen consumers.

Separate Jurisdiction: State AG coalitions can sue to enjoin mergers even when federal agencies enter consent decrees or clear transactions.
Settlement Agreements: Concluded via binding judicial consent decrees requiring asset spin-offs, price freezes, consumer protection funds, or employment commitments.
Local Market Harms: AGs focus on localized media, health systems, and retail price spikes.

Structural vs. Conduct Remedies

Antitrust regulators strongly disfavor behavioral promises, demanding clean structural divestitures to restore competition.

Asset Carve-outs: Transferring subscribers, regional licenses, or catalog properties to a capable third-party competitor.
Buyer Viability: Divestiture buyers must demonstrate financial capability to operate the spun-off asset competitively.
Targeting ΔHHI < 100: Carving out sufficient share so that net increase in market concentration falls below presumptive litigation triggers.