Demoted Lehman Officer Leaves for Credit Suisse By JENNY ANDERSON Erin Callan, whose rise and fall at Lehman Brothers transfixed Wall Street, has resigned to join Credit Suisse. The move comes a little more than a month after Ms. Callan, 42, was demoted as the chief financial officer of Lehman, which has been rocked by speculation that it might founder. At Credit Suisse, Ms. Callan will run the global hedge fund business. It is a high-profile hire for Credit Suisse and an unsurprising loss for Lehman Brothers. Ms. Callan, considered one of the most powerful women on Wall Street in...