For years, investors in U.S. stocks shrugged off threats — a government shutdown, fear of a euro collapse, a near U.S. debt default — and just kept on buying. At the sixth anniversary of the bull market in March, the Standard and Poor's 500 index had more than tripled in value.
Now, buyers are hard to find. A wave of selling has hammered major indexes, with the S&P 500 losing nearly 6 percent in the past week. That is its worst weekly slump since 2011, and leaves it close to what Wall Street calls a "correction," or a fall of 10 percent from a recent high.