Mixing commercial and investment banking was banned in 1933 by the Glass Steagall Act. The act was partially repealed in 1999 which allowed banks to engage in b

Mixing commercial and investment banking was banned in 1933 by the Glass Steagall Act. The act was partially repealed in 1999 which allowed banks to engage in both commercial and investment banking again. As far as I know banks have been able to engage in both since then.