Simpson Thacher & Bartlett faces professional negligence claims after missing a deadline to appeal a UK competition regulator's decision to block a merger between Aramark and Entier. The Competition Appeal Tribunal ruled that the elite law firm's error in filing the appeal one day late was not "exceptional" enough to warrant an extension, forcing Aramark to unwind its acquisition of Entier.

The Competition and Markets Authority had blocked the deal in January, citing antitrust concerns that the merger would combine two of three major players in the UK offshore catering, cleaning and maintenance services market. Aramark had four weeks to appeal but Simpson Thacher attributed the late filing to a "misinterpretation of the rules." The tribunal acknowledged the "substantial prejudice" to Aramark but upheld the strict deadline.

The ruling highlights the risks elite law firms face when representing major corporations. Simpson Thacher's equity partners earned an average of $7.7 million in 2024, while junior lawyers command base salaries of $225,000 annually. The case has drawn attention because the CMA blocks so few mergers - this was the first rejection in over a year.