Amaryllis Müller is Counsel at Cleary Gottlieb. Her practice covers all aspects of European and Belgian competition law, with a focus on the Digital Markets Act, cross-border merger control, abuse of dominance proceedings, cartel investigations and antitrust litigation including follow-on damages claims. She also advises on State aid and EU and Belgian regulatory law. She has represented clients in multiple cases before the European and Belgian authorities and courts. Her experience crosses a range of industry sectors with a focus on technology and telecommunications. Amaryllis joined the firm as counsel in 2025 after serving as senior antitrust counsel in the Brussels office of a major social media company for two years. During this time, she gained significant in-house experience advising on global antitrust matters, including compliance with digital regulation and day-to-day product counseling. Previously she worked at another international law firm in Brussels for nearly 10 years, including a 10-month secondment to their Washington, DC office. She writes and speaks regularly on a broad array of European competition law issues.