# Merger Guidelines Joint [[Antitrust Division]] and [[FTC]] statements of how the agencies will analyze proposed mergers. They are not law and bind no court — but because the [[Hart-Scott-Rodino Act]] made almost every significant deal pass through agency review first, the guidelines determine which transactions are ever litigated at all. **They are the most consequential non-binding documents in American economic regulation.** ## The editions - **1968** (Donald Turner) — purely structural concentration tables, following [[United States v. Philadelphia National Bank]] and [[Brown Shoe v. United States]]: a merger producing a firm above a set market share was presumptively unlawful. - **1982** ([[William Baxter]]) — replaces concentration ratios with the Herfindahl-Hirschman Index, introduces the hypothetical-monopolist / SSNIP test for market definition, and admits efficiencies and ease of entry as defenses. The Chicago-school edition; conceptually the framework still in use. - **1992 / 1997 / 2010** — successive revisions shifting weight from structure toward predicted competitive effects, unilateral-effects modeling, and efficiencies; the 2010 edition raised the presumption threshold to HHI > 2,500, which in practice meant few mergers were presumptively anything. - **2023-12-18** — eleven guidelines that lower the structural presumption back to HHI > 1,800 with ΔHHI > 100 (or a 30% share), add serial acquisitions, multi-sided platforms, partial ownership, and **labor markets** ([[Monopsony]]), and re-ground the analysis in [[United States v. Philadelphia National Bank]] and the text of the [[Clayton Antitrust Act]]'s Section 7. The [[New Brandeis Movement]]'s durable product. ## Why the document matters more than the cases Courts do not apply the guidelines, but they cite them, and the agencies apply them to the roughly two thousand deals a year that never see a courtroom. A change in the presumption threshold is therefore a change in the number of deals that get a second request, a divestiture demand, or an abandonment — the enforcement that happens in the shadow of litigation. That is why the 2023 revision was the movement's priority and why its survival was the surprise: [[Andrew Ferguson]] confirmed on February 18, 2025 that the guidelines remain in effect, on institutional grounds — "constant turnover undermines agency credibility" — and the [[Antitrust Division]] concurred. The right kept the toolkit. What changed, as the [[Antitrust Division]] page's HPE/Juniper and Live Nation record shows, is who decides when to use it. See [[US Antitrust and Monopoly Timeline]]. ## See Also - [[Antitrust Division]] · [[FTC]] · [[Hart-Scott-Rodino Act]] · [[Clayton Antitrust Act]] · [[Antitrust]] - [[United States v. Philadelphia National Bank]] · [[Brown Shoe v. United States]] · [[William Baxter]] · [[Andrew Ferguson]] · [[Lina Khan]] · [[Jonathan Kanter]] - [[New Brandeis Movement]] · [[Consumer Welfare Standard]] · [[Monopsony]] · [[US Antitrust and Monopoly Timeline]]