Lina Khan Is Upending Wall Street’s Merger-Arbitrage Playbook

Lina Khan is the most aggressive trustbuster the US has had in decades. Roughly two years into her tenure, Wall Street is still learning the hard way just how far she’ll take her fight against some of America’s most powerful businesses.

Merger-arbitrage investors — who bet on the likelihood that proposed acquisitions will close — just had one of their worst months since early 2020 after Khan, who heads the Federal Trade Commission, sued to block Amgen Inc.’s takeover of Horizon Therapeutics Plc.

Lina Khan

Photographer: Al Drago/Bloomberg

The move, after major setbacks in two other large pending transactions in previous weeks, ...