Bears made short work of yesterday’s rally, driving the Dow down 120 points at the open today after GM said its auditors doubted it could continue operating. The S&P sunk roughly 2%, while the Nasdaq fell 1.6%. GM shares plummeted 13%, and are trading below $2. Ford likewise declined 6%. There was a glimmer of hope, however, from Wal-Mart, which posted a 5.1% jump in same-store sales and raised its dividend. Shares rose 4%.