Stocks sunk swiftly at the open after disappointing sales reports from retailers. The Dow tumbled 160 points, while the Nasdaq and S&P fell 1.5% and 2.1% respectively. Retail sales were down a more-than-expected 0.4% in April, from a revised-downward 1.3% drop in March. RealtyTrac also announced a 32% jump in foreclosures last month, meaning a housing rebound isn’t imminent. Ford was down 4% as it prepared to sell 300 million shares in a secondary offering.