The Texas Lawbook launched the Texas Lawbook 50 and the Corporate Deal Tracker in 2015 — two exclusive databases that calculate the law firm headcounts and revenue in Texas. The CDT documented those law firms’ M&A and capital markets transactions.
Simpson Thacher didn’t make the leaderboard of either database in 2015.
A decade later, however, and the elite Wall Street corporate law firm is vaulting up both rankings by increasing its 2025 Texas headcount by 26 percent, its Texas revenue by 34 percent and leaping into the upper echelons of Texas dealmakers.
“This firm believes in Texas — we are definitely in growth mode, which starts with headcount,” Breen Haire, co-managing partner of Simpson Thacher’s Houston office said in an interview. “We have wonderful tailwinds behind us in energy and infrastructure. The demand for AI and power has been amazing.”
“The growth in demand for our services has been steady and increasing,” Haire said.
Texas Lawbook 50 shows that Simpson Thacher’s lawyer headcount in Texas jumped to 82 in 2025, up from 66 a year earlier and up from 21 attorneys in 2015.
More lawyers mean more income. Simpson Thacher’s 2025 Texas revenue hit $187.8 million — up from $25.6 million in 2015.
The firm, which represents 10 of the nation’s largest private equity firms, saw its revenue per lawyer in Texas reach an astonishing $2,254,000 in 2025, compared to an RPL of $2,017,000 for the rest of the New York firm last year.
The good times have extended into 2026 so far, according to Matt Einbinder, Simpson Thacher’s other co-managing partner.
“January and February are historically slower, but the first quarter has been as strong and probably stronger than last year,” Einbinder said. “Clients don’t come to us for garden variety advice. They come to us for their most complex and critical matters, and we are proud to partner with major players across the energy and infrastructure sectors on these transactions.”
The evidence of Simpson Thacher’s success in large-dollar dealmaking can be found in the Corporate Deal Tracker data, which shows that the firm’s Texas lawyers were involved in 14 M&A transactions valued at $1 billion or more in 2025.
Simpson Thacher partner Shamus Crosby led or co-led five separate billion-dollar M&A transactions in 2025 with a combined value of $40.5 billion. Haire advised three clients in billion-dollar transactions that had a combined $30 billion price tag.
Crosby and Haire jointly advised private equity giant KKR in its $22.2 billion purchase of Sempra Infrastructure Partners.
Other Simpson Thacher transactions in the CDT from 2025 include:
- Advised WhiteWater Midstream in multiple transactions, including the sale of its interests in BANGL to MPLX for $715 million;
- Represented Kimmeridge in its sale of a 24.1 percent interest in Kimmeridge’s SoTex HoldCo to Mubadala Energy;
- Advised J.P. Morgan in multiple transactions, including a $3.5 billion revolving credit facility for Expand Energy Corporation;
- Represented EOC Partners and other lenders in Northwind Midstream Partners’ issuance of a $700 million senior first lien term loan;
- Advised Group 1 Automotive in its $3.5 billion revolving credit facility; and
- Represented American Electric Power in its $2.3 billion common stock offering with a forward component and Capital Power in its $1.2 billion senior notes offering.
Simpson Thacher announced earlier this year that it plans to open its second Texas office in Dallas this year.
“It is exciting for us to be in Dallas, because what made us successful in Houston will make us successful in Dallas,” Breen said.
Einbinder agreed.
“The Dallas landscape offers a similar client base that we have in Houston — private equity and a number of banking clients,” he said.
About Texas Lawbook 50
The Texas Lawbook 50 is the result of multiple efforts, including direct survey responses from about 70 law firms operating in Texas regarding their headcount, total revenues, revenues per lawyer and profits per equity partner. Most firms provided the requested data. Other law firms provided simple lawyer headcount and RPL, which were used to calculate Texas revenues. The Lawbook also used other sources, including interviews with key partners, former partners, legal industry analysts, as well as data from publications such as American Lawyer and other third-party sources that collect and analyze firm revenues.