Simpson Thacher & Bartlett LLP is a prominent white-shoe international law firm headquartered in New York City, specializing in corporate law, mergers and acquisitions, private equity, securities litigation, capital markets, banking and credit, restructuring, and regulatory advice. Founded on January 1, 1884, by John Woodruff Simpson, Thomas Thacher, and William Milo Barnum as Simpson, Thacher & Barnum, the firm has grown to employ approximately 1,500 to 2,000 attorneys across 13 to 14 offices worldwide, including New York, Los Angeles, Palo Alto, San Francisco, Houston, Washington D.C., London, Tokyo, Hong Kong, Beijing, Brussels, Luxembourg, São Paulo, and Boston. It reported revenue of US$2.9 billion in 2024 and is led by Executive Committee Chairman Alden Millard. The firm represents major clients such as investment banks (e.g., Lehman Brothers historically, JPMorgan Chase), private equity firms (e.g., Kohlberg Kravis Roberts on the 1989 RJR Nabisco deal), and tech companies (e.g., Google IPO, YouTube, Facebook IPO). The firm's history includes key name changes: Reed Simpson Thacher & Barnum in 1889 after Thomas Brackett Reed joined, Simpson Thacher Barnum & Bartlett post-1902, and its current name in 1904 following William Barnum's retirement. It pioneered milestones like appointing the first African American partner in a U.S. law firm in 1969 and expanded internationally starting with London in 1978, followed by Tokyo (1990), Hong Kong (1993), and others. From its original 9 Pine Street location, it moved to 425 Lexington Avenue opposite Grand Central Terminal. Simpson Thacher maintains a collegial culture, operating as a single firm across offices with practices in areas like antitrust, real estate, REITs, fund finance, and national security regulation. Notable for advising on landmark transactions such as the largest private equity buyout at the time (RJR Nabisco, 1989) and recent matters like Mattress Firm's acquisition by Tempur Sealy, Cisco's acquisition of Splunk, and JPMorgan's Apple Card portfolio, the firm emphasizes client collaboration, diversity initiatives, and high rankings in legal awards.