December 2020 -- Keystone Strategy made its debut in the last edition of GCR100's Economics 21. The practice specialises in antitrust matters in technology markets, taking on a large caseload as competition enforcers around the world home in on the conduct of digital platforms. Keystone consults on more than just economics, offering a broad array of advisory work to high-tech firms and their critics. In the past year, the team has added former Google employee Ryan Drake-Lee and Jennifer Graves, who previously worked at Starbucks and Bain & Company. Keystone counts major digital platforms such as Facebook, Amazon, Apple, and Microsoft as clients, but it has also advised Oracle, News Corp, AT&T, Expedia and Turo. In recent years, the consultancy has done work evaluating antitrust theories of harm related to privacy, algorithmic markets and whether enforcers should use metrics that extend beyond that of consumer welfare. Most of the team's merger work remains confidential, although principal Jennifer Redmond prepared materials for the US Department of Justice's antitrust division for its February 2020 public workshop on venture capital and antitrust. Previously disclosable U.S. work includes Susan Athey testifying about potential merger efficiencies in the AT&T/Time Warner deal on behalf of the DOJ. Athey also worked on the team that advised the Federal Trade Commission in its successful administrative proceedings against 1-800 Contacts, alleging that the retailer illegally siphoned off competition for search advertisements by claiming trademark violations. The U.S. Court of Appeals for the Second Circuit heard oral arguments in that appeal in March 2020. View the full ranking here.