A mergers and acquisitions associate at Sullivan & Cromwell has sued the firm alleging a pattern of discrimination against him on the basis of sexual orientation. [The plaintiff] Aaron B. Charney accuses several of the firm's top partners of discriminating against him because he is gay. He also claims the firm initiated a retaliatory campaign after he filed an internal complaint, culminating in the issuance of a fabricated performance review. In a statement ..., chairman H. Rodgin Cohen said the firm categorically denied Charney's allegations.