A Dallas businessman has sued Weil, Gotshal & Manges, alleging that the firm and two of its partners took advantage of him as a client by lessening his interest in a deal while he was undergoing treatment for cancer.

In David M. Radman, et al. v. Richard M. Boyd, et al., Radman — individually and as trustee of the DMR Trust — and CU Commercial Services LLC allege that the firm and two of its Dallas partners, Michael A. Saslaw and Robert C. Feldman, conspired with Radman’s then-business partner and others to reduce Radman’s interest in a proposed acquisition of a Dallas-based credit union subsidiary.