"By bidding up stock prices all year, investors were effectively betting the housing slowdown wouldn't engulf the broader economy. Yesterday, that confidence appeared to be shaken.</br></br>Stocks and corporate-bond markets tumbled amid selling that was more widespread than during the three previous days of triple-digit declines this month. Along with risky bonds and anything connected to the housing market, investors sold off stocks, emerging-markets bonds and even high-quality corporate debt. The record trading volume in stocks reflected rising anxiety.</br></br>Meanwhile, roughly 1,300, or nearly 17%, of the around 7,800 stocks that trade on U.S. exchanges hit their lowest price of the past 12 months.</br></br>To many investors, that made yesterday's selloff more ominous than other big declines this year. Sid Bakst, a senior portfolio manager at investment firm Robeco Weiss, Peck & Greer, said the steady drip of bad news on subprime-mortgage loans and the failure of some leveraged buyouts to get long-term financing has made investors increasingly nervous.</br></br>""As each day has gone by, things have been leaking a bit more,"" Mr. Bakst said. ""But today there was full-blown carnage."""