During the Japanese stock market boom in the late 1980s, investment bankers persuaded many Japanese companies to raise capital by issuing bonds with warrants attached, although they did not require the funds for operational purposes. Clients were tempted by the potential returns the investment firms said they could generate on stock market investments. However, as stock values fell, companies were in a vicious circle where not only their investments soured, the debt remained after issued warrants expired, weakening the companies' capital base.