Merrill Lynch and Lehman Brothers rode similar paths of decline but had vastly different endgames.

Erin Callan, whose rise and fall at Lehman Brothers transfixed Wall Street, has resigned to join Credit Suisse.

Erin Callan, whose rise and fall at Lehman Brothers transfixed Wall Street, has resigned to join Credit Suisse.

Moody’s Investors Service said it had placed Lehman Brothers Holdings on review for a possible downgrade, citing executive changes at the bank.