Chicago--The short-term economic pressure Wall Street and boards of directors are exerting on companies, apparently, is making its way to the executive suite. The average tenure of departing CEOs was just 5.7 years in 2001, according to outplacement firm Challenger, Gray & Christmas. The recession and the negative economic effects of Sept. 11 are pushing CEOs out of their jobs at a rapid clip. CEO turnover surged in October, with 80 top executives leaving during the month, according to Challenger, Gray. Sixty-one CEOs left in September.