Sidley Austin LLP

Sidley Austin is a global powerhouse with a long list of clients from Fortune 500 companies to startups in a range of industries, including energy, financial services, healthcare, insurance, life sciences, sports and media, and technology. With over 2,300 lawyers across 21 offices who collaborate across disciplines and borders, Sidley helps clients in more than 70 countries with cross-border transactions, investigations, restructurings, crisis management, litigation, and regulatory matters.

Chicago and New York Powers Unite

Sidley traces its history back to the 1860s in Chicago and has represented marquee clients from the start, including former first lady Mary Todd Lincoln, George Pullman, and the Western Union Telegraph Company (later AT&T). The Chicago-based firm merged in 2001 with a top Wall Street-founded law firm, creating the Sidley Austin LLP that clients today look to for counsel. 

Elite Platform, Cross-Border Capabilities

Among the firm’s top practices are M&A and private equity, litigation, restructuring, life sciences, energy, environmental law, capital markets, Supreme Court and appellate, securities enforcement and regulatory, and white collar and government investigations, all of which the firm handles for clients worldwide. Sidley’s 750 litigators deploy innovative legal strategies at each stage of litigation, representing clients nearly anywhere they find themselves facing a dispute. In the 2024 edition of Global Investigations Review’s GIR 100, the firm ranked among the top two law firms in the world for cross-border corporate investigations.

Sidley handles private equity, M&A, and broader corporate matters across major international markets. Clients include public and private companies, private equity funds and other financial sponsors, boards of directors, special committees, and financial advisers. Since 2022, Sidley handled over 1,915 private equity/M&A transactions worth more than $795 billion in deal value, earning continued recognition in global M&A league tables, as well as No. 1 rankings for company representations in all the major activism league tables, including Bloomberg, FactSet, LSEG, and Diligent.

The firm’s Supreme Court and appellate practice has secured victories in each of the 13 courts of appeals and the U.S. Supreme Court in the past two years. Since 2010, Sidley lawyers have briefed over 250 Supreme Court cases on the merits, argued over 150 cases before the U.S. Supreme Court, and had a hand in over 450 cases in federal appellate courts. The firm needs four hands to count how many times it has been named to The National Law Journal’s Appellate Hot List and is regularly ranked in Vault’s Appellate rankings.

Clients also turn to the firm to navigate the regulatory, policy, and compliance challenges that arise in conducting business across borders. The firm’s cross-border team is well-versed in local laws across jurisdictions and includes over 100 lawyers who were former officials at key regulatory agencies around the globe. The firm was highly ranked by Chambers Global in 2025 for international and cross-border work in corporate/M&A, disputes, energy, investigations and enforcement, finance and capital markets, investment funds and asset management, life sciences and pharmaceuticals, and technology.

Impacting the World

Through its robust pro bono program, Sidley lawyers work on matters involving veterans advocacy, constitutional rights and civil liberties, and asylum and immigration. The firm has also tackled pressing cases before the Supreme Court and defended the rights of prisoners on death row. As part of its social responsibility program, the firm provides charitable donations to various organizations, and lawyers and business professionals at the firm log many hours of volunteer work, expanding its efforts to contribute to local communities each year.

• Sidley is representing Clearlake Capital Group, L.P., in its $7.7 billion take-private acquisition of Dun & Bradstreet Holdings, Inc.
• Sidley is representing Arthur J. Gallagher in its $13.45 billion acquisition of AssuredPartners from GTCR.
• Sidley secured significant victories in two of Monsanto’s Roundup product liability cases in the Philadelphia Court of Common Pleas, where a number of high-dollar verdicts have been rendered in product liability trials over the past year.
• Sidley scored a major victory on behalf of the Big 12 Conference in the Southern District of New York, obtaining total dismissal with prejudice of a putative antitrust class action brought by former college basketball stars Mario Chalmers, Jason Terry, and fourteen other former student-athletes (“Litigator of the Week Shout Out”—The American Lawyer’s Litigation Daily, 2025).

• One of The Best Companies for Future Leaders in the United States, the only law firm to be featured, 2024—TIME
• Excellent Performer for Career Development, Associate Retention, Quality of Life, and Pro Bono; Strong Performer for Diversity, Equity & Inclusion; and Endorsed for Associate Satisfaction according to the Associate Satisfaction Survey, 2024—Chambers Associate
• 133 practice rankings and 307 lawyer rankings, of which 28 practice rankings and 48 lawyer rankings were in Band 1, 2024—Chambers USA
• Corporate Practice of the Year Finalist, The American Lawyer Industry Awards, 2024—Law.com
• Law Firm of the Year in Litigation: Regulatory Enforcement (SEC, Telecom, Energy), based on the Best Law Firms Survey, 2025—Best Lawyers