Sonnenschein, Nath & Rosenthal announced late Sunday that 100 lawyers, including 40 partners, from Thacher Proffitt & Wood will be joining the firm’s New York office, effective January 1. The hires increase Sonnenschein’s total headcount to about 800 lawyers, nearly doubling the size of its New York office — it’s the biggest group of laterals ever taken on by Sonnenschein, according to senior managing director Audrey Young.

Sonnenschein is drawing from all of Thacher’s existing practices, including structured finance (representing the largest number of additions, with 26 partners and of counsel), corporate, banking, real estate, regulatory and litigation.