On December 18, 2023 the FTC and DOJ jointly issued the 2023 Merger Guidelines, which describe the factors and frameworks the agencies utilize when reviewing mergers and acquisitions. The first draft was issued in July, and in the following months the agencies hosted several workshops and received over 30,000 comments from “consumers, workers, academics, interest organizations, attorneys, enforcers, and many others.” The final reflects some of that feedback. The final version reduces the 13 originally proposed guidelines down to 11, removing and merging some of the guidelines in the final. Among other changes, the final version eliminates the draft appendix of economic analysis in favor of a section outlining “a non-exhaustive discussion of analytical, economic, and evidentiary tools the Agencies use to evaluate facts, understand the risk of harm to competition, and define relevant markets.” Many critics say the changes from the draft to final copy are mostly stylistic in nature, including the removal of the biblical-like “thou shall not” phrasing at the top of each guideline. Importantly, the final merger guidelines maintain the lower market share concentration levels as the July version, opening more transactions to scrutiny and potential challenge. That includes the presumptions that a deal likely would lead to too much industry concentration if it would give the combined firm a more than 30% market share, if a newly vertically integrated company would gain control of 50% of a related market, and if a deal reaches a lower concentration threshold than the one identified in the 2010 guidelines the new version replaces.