sentences:  Since the founders established MDP as an independent firm in 1992, the firm has raised seven funds with aggregate capital of approximately $23 billion, and has completed investments in more than 130 companies.Madison Dearborn Partners was founded in 1992 and is based in Chicago, Illinois.The founders, John A Canning Jr, Paul J. Finnegan, Samuel M. Mencoff, and Nicholas W. Alexos had previously made private equity investments for First Chicago Bank.