Simpson Thacher & Bartlett
An internationally prominent American law firm focused on complex corporate transactions, private equity, and litigation.
Last updated August 21, 2026
AI crawler reads
No AI crawler has read this profile since Oct 28, 2026.
Overview
Simpson Thacher & Bartlett LLP is a New York-headquartered American law firm commonly associated with the white-shoe segment of the legal profession. Its principal practices include mergers and acquisitions, private equity, securities and capital-markets work, banking and finance, litigation, antitrust, restructuring, intellectual property, and regulatory matters. The firm advises public companies, financial sponsors, investment banks, technology businesses, industrial companies, and other major institutions on transactions and disputes with substantial commercial or strategic importance. The firm traces its origin to January 1, 1884, when John Woodruff Simpson, Thomas Thacher, and William Milo Barnum organized Simpson, Thacher & Barnum at 9 Pine Street in New York City. The partnership went through several name changes as prominent lawyers joined or departed. Thomas Brackett Reed, a former Speaker of the U.S. House of Representatives, joined in 1889, producing the name Reed Simpson Thacher & Barnum. After Reed's death, Philip Bartlett became a name partner, and the firm adopted the name Simpson Thacher Barnum & Bartlett. Barnum's retirement in 1904 led to the final form, Simpson Thacher & Bartlett. For much of its history the firm was identified with elite New York corporate and litigation practice. It later built a wider U.S. and international network. London opened in 1978, followed by Tokyo in 1990, Hong Kong in 1993, Los Angeles in 1996, Palo Alto in 1999, Washington, D.C. in 2005, Beijing in 2007, São Paulo in 2009, and Brussels in 2021. The firm has also announced plans for Boston and San Francisco offices. Its New York headquarters is at 425 Lexington Avenue, opposite Grand Central Terminal. Simpson Thacher's transaction practice has been involved in several landmark matters. Examples include advising KKR on the 1988 RJR Nabisco acquisition, representing Google in its initial public offering and YouTube acquisition, advising Tesla in its 2010 IPO, assisting Facebook's underwriters in its 2012 offering, representing Alibaba in its 2014 record-setting IPO, and advising Microsoft on its acquisitions of LinkedIn and GitHub. These matters helped reinforce the firm's profile in private equity, technology, securities, and high-value mergers and acquisitions. The firm has also experienced episodes that illustrate the risks of large-scale legal practice. In connection with a JPMorgan Chase transaction in 2008, a documentation error unintentionally altered the security status of another loan; the error contributed to losses after General Motors entered bankruptcy. In 2025, the firm agreed to provide significant pro bono legal services in response to demands from the second Trump administration targeting major law firms. Shortly afterward, Microsoft reportedly moved its legal matters from Simpson Thacher to Jenner & Block. The firm has also drawn public attention for its involvement in statements concerning antisemitism and campus protests related to the Israel-Gaza conflict. Simpson Thacher remains an active global law firm with approximately 1,500 attorneys across 13 offices according to the cited reference material. It is regularly placed among the leading U.S. firms in legal-industry rankings, particularly for profitability, corporate transactions, private equity, and high-end litigation.
History
Simpson Thacher & Bartlett began on January 1, 1884, in New York City as Simpson, Thacher & Barnum. Its founders—John Woodruff Simpson, Thomas Thacher, and William Milo Barnum—had previously served as law clerks at Alexander & Green. The original office was located at 9 Pine Street. The firm's identity developed through successive additions to its partnership. In 1889, former U.S. House Speaker Thomas Brackett Reed joined, and the practice became Reed Simpson Thacher & Barnum. Reed's death in 1902 was followed by the addition of Philip Bartlett as a name partner, creating Simpson Thacher Barnum & Bartlett. When Barnum retired in 1904, the firm assumed the name it retains today. The practice moved among several New York locations before establishing its current headquarters at 425 Lexington Avenue near Grand Central Terminal. Its growth was initially centered on New York's corporate, financial, and litigation markets, but the firm gradually developed a national and international footprint. London became its first international office in 1978. Tokyo followed in 1990, Hong Kong in 1993, Los Angeles in 1996, Palo Alto in 1999, Washington, D.C. in 2005, Beijing in 2007, São Paulo in 2009, and Brussels in 2021. The firm later announced expansion plans in Boston and San Francisco. A significant institutional milestone occurred in 1974, when Conrad Harper joined the partnership. A civil-rights lawyer formerly associated with the NAACP Legal Defense Fund, Harper was only the second Black partner at a major New York law firm. His legacy is reflected in the Conrad Harper 2L Diversity Fellowship, which supports eligible law students from underrepresented backgrounds. The firm became especially prominent in major corporate transactions and financial markets. In 1988 it advised KKR on the acquisition of RJR Nabisco, then the largest private-equity buyout. It later represented Google's underwriters in the company's 2004 IPO and Google in its acquisition of YouTube in 2006. Other notable matters included Tesla's 2010 IPO, Facebook's 2012 IPO, Alibaba's 2014 IPO, Microsoft's acquisitions of LinkedIn and GitHub, and numerous private-equity and public-company transactions. Its record also includes a notable documentation failure. In a 2008 JPMorgan Chase transaction, an error unintentionally converted a separate secured loan into an unsecured obligation. When the debtor, General Motors, filed for bankruptcy in 2009, the mistake exposed JPMorgan Chase to losses of up to $1.5 billion. The reference material states that Simpson Thacher did not create the original error but failed to identify it. In the 2020s, the firm became involved in debates about law-firm hiring, campus protest activity, antisemitism, and government pressure on elite legal practices. It signed a 2021 statement condemning antisemitic attacks and in 2023 joined firms warning law-school leaders that incidents characterized as antisemitic could affect recruiting. In 2025, amid executive-branch pressure on law firms, Simpson Thacher agreed to provide $125 million in pro bono services for administration-backed causes. Microsoft subsequently transferred its legal matters to Jenner & Block. These events placed the firm at the intersection of professional ethics, client relationships, political pressure, and institutional independence.
- 2025
San Francisco expansion announced
[1]The firm announces plans for a San Francisco office in space formerly occupied by Google.
- 2024
Boston expansion announced
[1]Simpson Thacher announces plans for a Boston office.
- 2021
Brussels office opens
[1]The firm expands its European presence with a Brussels office.
- 2014
Alibaba IPO representation
[1]The firm represents Alibaba in its record-setting initial public offering.
- 2004
Google IPO representation
[1]Simpson Thacher represents the underwriters in Google's initial public offering.
- 1988
RJR Nabisco transaction
[1]The firm advises KKR on its landmark acquisition of RJR Nabisco.
- 1978
London office opens
[1]The firm begins its international office expansion with a London location.
- 1974
Conrad Harper joins partnership
[1]Conrad Harper becomes one of the earliest Black partners at a major New York law firm.
- 1904
Current firm name adopted
[1]Following Barnum's retirement, the partnership becomes Simpson Thacher & Bartlett.
- 1889
Thomas Brackett Reed joins
[1]The former U.S. House Speaker joins the partnership, which adopts the name Reed Simpson Thacher & Barnum.
Products and positioning
Premium commercial law firm serving major corporations, financial sponsors, investment banks, and institutions on complex, high-value transactions and disputes.
Corporate legal services
Mergers and acquisitions
The firm advises corporate clients, private-equity sponsors, financial institutions, and strategic buyers and sellers on negotiated acquisitions, takeovers, divestitures, joint ventures, and other complex combinations. Its work includes transaction structuring, diligence, negotiations, financing coordination, securities-law compliance, and closing execution.
Investment and corporate legal services
Private equity
Simpson Thacher represents private-equity funds and portfolio companies throughout the investment cycle, including fund formation, leveraged acquisitions, minority investments, exits, recapitalizations, and associated financing. The practice is closely connected to the firm's reputation in major sponsor-led transactions.
Financial legal services
Securities and capital markets
The practice supports issuers, underwriters, selling shareholders, and financial institutions in IPOs, follow-on offerings, debt offerings, and other capital-markets transactions. Notable historical matters include the IPOs of Google, Tesla, Facebook, and Alibaba.
Dispute-resolution services
Litigation and disputes
The firm handles high-value commercial litigation, securities disputes, antitrust matters, investigations, appeals, and other contentious proceedings. Its litigation work complements its corporate practice by advising companies and financial institutions before, during, and after significant transactions or regulatory conflicts.
Financial legal services
Banking, finance, and restructuring
Simpson Thacher advises lenders, borrowers, sponsors, and distressed businesses on secured lending, acquisition finance, leveraged finance, restructurings, and insolvency-related matters. The practice has also been associated with a widely reported documentation error in a 2008 JPMorgan transaction.
Controversies
2025
Response to executive pressure on law firms
During the second Trump administration's campaign against several major law firms, Simpson Thacher agreed to provide $125 million in pro bono legal work for causes supported by the administration. The decision generated scrutiny concerning professional independence and the relationship between government pressure and private legal representation.
2009
JPMorgan loan-documentation error
A mistake in a 2008 transaction unintentionally changed a separate $1.5 billion secured loan into an unsecured loan. The error was not caught before General Motors entered bankruptcy, exposing JPMorgan Chase to potentially substantial losses. The reference material says the firm did not originate the mistake but failed to detect it.
Marketing campaigns
- 2023Law-school recruiting warning
United States
The firm joined other major law firms in warning law-school deans that escalating campus incidents described as antisemitic could have consequences for corporate hiring.
Outcome. Public letter to law-school leadership
- 2021Global statement against antisemitism
United States · Global
Simpson Thacher joined 16 other global law firms in a public statement condemning increased antisemitic attacks in the United States.
Outcome. Public signatory statement
Brand decisions
2025
Agree to administration-backed pro bono commitmentStrategyBackground
The firm faced demands during a broader government campaign targeting major law firms under the second Trump administration.
Action taken
Simpson Thacher agreed to provide $125 million in pro bono legal work for causes backed by the administration.
Aftermath
Microsoft subsequently transferred its legal matters from Simpson Thacher to Jenner & Block, according to the reference material.
Pro bono commitment. $125 million (2025)
2014
Represent Alibaba in initial public offeringProduct launchBackground
Alibaba pursued a major public offering in the United States as it expanded its global capital-markets profile.
Action taken
The firm represented Alibaba in its initial public offering.
Aftermath
The offering raised $25 billion and was described in the reference material as the largest IPO at the time.
IPO proceeds. $25 billion (2014)
1988
Advise KKR on RJR Nabisco acquisitionM&ABackground
KKR pursued the acquisition of RJR Nabisco in a transaction that became a defining example of leveraged buyouts and private-equity dealmaking.
Action taken
Simpson Thacher advised KKR on the $25.1 billion acquisition.
Aftermath
The transaction became widely known through the book Barbarians at the Gate and strengthened the firm's association with landmark private-equity matters.
Transaction value. $25.1 billion (1988)
Recent events
- 2025
Microsoft transfers legal matters away from Simpson Thacher[1]
Leadership change · Other
Two weeks after the firm's agreement with the administration, long-time client Microsoft moved its legal matters to Jenner & Block.
- 2025
Firm announces planned San Francisco office[1]
Other
The firm signed a lease for former Google office space and announced plans to open a San Francisco office in 2026.
- 2024
Firm announces planned Boston office[1]
Other
Simpson Thacher announced plans to establish a Boston office as part of its continued U.S. expansion.
- 2023
Law firms warn law schools over campus antisemitism and recruiting consequences[1]
Regulation · Other
Simpson Thacher joined other major firms in warning leading law-school deans that escalating incidents described as antisemitic could affect corporate hiring decisions.
- 2021
Simpson Thacher signs statement denouncing antisemitic attacks[1]
Other
The firm was among 17 global law firms signing a public statement condemning rising antisemitic attacks in the United States.
Sources1 sources
Cite this profile: Cite the canonical profile. /brand-wiki/simpson-thacher-and-bartlett · Editorial policy · How profiles are compiled