Conflicts of interest often arise in relation to investment banks' equity research units, which have long been part of the industry. A common practice is for equity analysts to initiate coverage of a company in order to develop relationships that lead to highly profitable investment banking business. In the 1990s, many equity researchers allegedly traded positive stock ratings for investment banking business. Alternatively, companies may threaten to divert investment banking business to competitors unless their stock was rated favorably. Laws were passed to criminalize such acts, and increased pressure from regulators and a series of lawsuits, settlements, and prosecutions curbed this business to a large extent following the 2001 stock market tumble after the dot-com bubble.