About half the stocks making up the S&P 500 broad index are entering "correction" territory, USA Today reports. A correction is generally described as 10 percent drop off a recent high, and 274 S&P 500 stocks are down 10 percent from 52-week highs.
Meanwhile the Dow Jones Industrial Average, which saw only one triple-digit loss in the first three months of the year, saw three such drops in the past week.
Experts agree it's time to fasten seatbelts and brace for a bumpy ride.
"We're seeing a growing number of stocks entering confirmed downtrends," says Craig Johnson of Piper Jaffray, USA Today adds.
"It tells you we're due for a pause."
Sluggish growth in the U.S. and fears the European debt crisis may be rekindling are sending stocks falling.
Fears that earnings are set to cool their growth are priming the selloff as well.
Meanwhile in Europe, yields have been rising in Spanish government bond auctions, approaching 6 percent on concerns the debt crisis there is back from hiatus.
The European Union, European Central Bank and the International Monetary Fund recently arranged a $172 billion bailout for Greece, which has calmed markets in recent weeks.
However, experts point out that bailout funds provide temporary relief for indebted countries but don't solve underlying problems of not enough growth and too much debt.
"They've managed to put a Band-Aid on the debt crisis, but there's really no solution," says Colleen Supran, a principal at the investment adviser Bingham, Osborn & Scarborough, according to the Associated Press.
"And Spain is a much bigger problem than Greece."
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