In 1931, he bought his seat on the New York Stock Exchange for $235,000 (). It was reported that he used some of the large inheritance received from his mother to found the Washington, DC brokerage firm of "Auchincloss, Parker & Redpath" with Chauncey B. Parker and Albert G. Redpath. The firm eventually had 16 offices with two in New York City and the rest spread along the East Coast. In 1970, the firm merged with Thomson & McKinnon, a brokerage house based in New York. At the time of the merger, the new firm, known as Thomson & McKinnon Auchincloss, had assets of $160 million () and 58 offices. By the time of his Auchincloss' death in 1976, the firm was known as Thomson & McKinnon Auchincloss Kohlmeyer.