William Hinman, who was Shearmans' managing partner in San Francisco and Menlo Park, and business finance partner Kevin Kennedy are leaving for the rival New York firm.
Shearmans has significantly increased its West Coast presence recently, sending in four top partners and a team of associates to beef it up over the last couple of months (The Lawyer, 19 June).
Hinman was made head of the firm's global technology group when Peter Lyons, the firm's worldwide co-head of M&A, relocated from New York and took over the position of managing partner.
Simpson Thacher moved into Silicon Valley last September with four New York partners and senior litigation partner George Newcombe at the helm. Newcombe works with litigator Jim Kreisman and corporate M&A capital markets specialists Richard Catpuleto and Mike Nooney.
It is understood that Hinman and Kennedy are moving because they believe that Simpson Thacher is more focused on Silicon Valley while Shearmans is focussed on expansion into Europe and Asia.
Newcombe says the arrival of the pair is a real boost to the practice. "They provide meaningful expansion of our already distinctive capabilities in the core areas of our practice - corporate finance, private equity transactions, mergers and acquisitions, and litigation. And they extend our strengths in serving clients in technology-related areas," he says.
Hinman's practice has included debt and equity offerings of high technology, healthcare and biopharmaceutical companies, and general corporate work for a variety of issuers and underwriters.
Kennedy helped found Shearmans' Menlo Park office and headed the venture capital practice group in California. He has served as primary outside counsel for a number of public and private companies and has represented issuers and underwriters in a variety of transactions in technology, consumer products and biotech industries.
Shearmans' managing partner Whitney Pidot says: "We have had an office in the Bay Area for 20 years, and another in [Silicon] Valley, before most of our competitors.
"Our technology practice is a global one and its centre of gravity is not as concentrated in the Valley as that of other firms. Even so, we have sent new leadership there to begin a major expansion."