Millstein & Co. operated as an independent financial advisory and principal investment firm focused on complex restructuring, mergers and acquisitions, and capital raising. The firm advised corporate boards, institutional creditors, and government entities navigating challenging fiscal situations.

The multidisciplinary team combined legal, financial, and regulatory expertise to negotiate recapitalizations and liability management programs. In September 2018, Millstein & Co. was acquired by Guggenheim Securities to strengthen its restructuring and restructuring advisory practice.