A variety of factors, including investors’ unease over a lack of economic growth in the U.S. and Europe, caused the Dow (DJIA) and S&P 500 to drop 1.01% and 0.95%, respectively – the second day in a row of losses for both indexes. The Dow was down more than 200 points at certain times during trading before finishing with a loss of 167.16 points. It was the Dow’s biggest drop since April 10.

Meanwhile, the S&P 500 (SPX) dropped 17.68 points, or nearly 1%.  Thursday was also the third straight day of losses for Nasdaq (COMP), which closed down 0.76%.

The Dow set trading records on each of the week’s first two days, reaching as high as 16,755.51 on Tuesday before closing more than 140 points below that mark the next day. The S&P 500 touched 1,900 for the first time ever in mid-day trading on Tuesday before closing just below the threshold and  then suffering a 0.5% dip on Wednesday.

MORE: Retailers exit first quarter with higher inventory

Instead of pumping money into stocks, investors piled into the bond market, pushing down yields as bond prices went up. The yield for 10-year Treasury notes closed at just 2.50%, the lowest rate since October 2013.

Adding to investors’ concerns, Appaloosa Management’s David Tepper – the country’s highest paid hedge fund manager, who took home a reported $3.5 billion last year – talked about his own concerns with the market at the SALT Investing Conference in Las Vegas today. Fortune reported that Tepper told a group of conference attendees that this “is a nervous time” for investors due to the negative effect sluggish economic growth in the U.S. and abroad is likely to have on the stock market.

The U.S. GDP grew by just 0.1% in 2014’s first quarter while the European economy also fell short of expectations, growing by 0.2% during the same period. Today’s U.S. market volatility was preceded by rocky trading in Europe, where Germany’s DAX index briefly soared to a record high on before ultimately falling 1% at the close.

MORE: David Tepper: I’m nervous about the market

Thursday also brought bad news for retailers including Walmart (WMT), which reported its lowest quarterly growth in almost five years after a rough winter kept shoppers away. Several other retailers also blamed severe weather for weak sales numbers, including Macy’s Inc. (M) and Kohl’s Corp. (KSS).

On the other hand, Zendesk, a company that provides technology for handling customer support, helped to restore a bit of confidence in tech IPO market, which has been in turmoil recently with investors fleeing companies like Twitter and Zynga. Zendesk’s shares rose nearly 50% today, their first day of trading, closing at $13.43, after initially pricing at $9.