Brady Dougan, the former chief executive of Credit Suisse, is plotting a second act on Wall Street.

Dougan, an American whose tumultuous eight-year run atop the Swiss lender ended in summer 2015, is developing plans to launch a boutique financial firm that would both advise and invest in companies, according to people familiar with the matter. The effort remains at an early stage, and Dougan hasn't yet committed to the idea, the people said.