Holwell Shuster & Goldberg, a five-year-old boutique that continues to be flush with litigation work from the financial crisis, will double its office space when it moves into three subleased floors from Simpson Thacher & Bartlett in midtown Manhattan by the end of the year.

Holwell Shuster’s move to 425 Lexington Ave., under a new 16-year sublease with Simpson Thacher, comes as the firm’s head count has reached 65 attorneys. Founding partner Richard Holwell said the firm envisions adding another 25 to 35 lawyers at most.