Harvey Pitt, who was the chairman of the Securities and Exchange Commission under President George W. Bush for only 18 months, has passed away at the age of 78. His career had three parts. First, he began his career at the S.E.C. and became general counsel when he was just 30 years old, the youngest ever to achieve that rank. After three years, he left to represent corporate clients for the powerful law firm Fried Frank and helped the firm become extremely profitable. In 2001, he returned to the S.E.C. as chairman, achieving renown for overseeing the swift reopening of U.S. stock exchanges after the 9/11 attacks. However, his popularity waned amidst a number of corporate accounting scandals, especially at Enron, which drew attention to his prior corporate work. Ultimately, Pitt resigned due to the revelation that he had failed to tell White House or his fellow S.E.C. commissioners that an accounting board chairman he championed had headed the audit committee of a company accused of fraud. Pitt’s sudden death followed a bout of illness, though the specifics have not been disclosed.