Thierbach, who joined as a partner from Sullivan & Cromwell in 1995, was instrumental in establishing Linklaters’ highly regarded US securities and corporate practice in London.
The departure leaves Cecil Quillen as leader of the practice.
Thierbach, whose next move is not yet known, represented underwriters and issuers on a number of equity and debt security transactions.
His clients are thought to include many of the leading investment banks, such as Deutsche Bank, Goldman Sachs and Credit Suisse.
The firm’s global head of finance John Tucker commented: “Steve had an important role in the development of our US securities practice. Anyone who’s made such a terrific contribution will be missed, but we have a very strong team here. We wish him well.”