Updated from 4:09 p.m. EDT

Tech stocks closed sharply lower, as the Nasdaq Composite logged its fifth straight losing session and fell to its lowest levels in six weeks.

After trending lower through much of the day, the tech-heavy index pierced its 200-day simple moving average of 1933.65, and finished down 38.63 points, or 1.97%, to 1920.15.

The Dow Jones Industrial Average was also dragged down by the Nasdaq's late-day swoon after being positive for most of the session. It finished off 46.70 points, or 0.45%, to 10,225.57, while the S&P 500 was down 6.65 points, or 0.6%, to 1107.24. The 10-year Treasury note traded up 9/32 in price to yield 4.5%, while the dollar was stronger against the yen and about even with the euro.

In another day of heavy trading, volume on the New York Stock Exchange exceeded 1.6 billion shares, and decliners led advancers by about 3 to 2. On the Nasdaq, nearly 2.2 billion shares changed hands, and decliners beat advancers by about 7 to 3.

"We're testing some pretty key support areas here, and we're not really doing it very successfully," said John Hughes, shortly before the close. "We're going into the weekend, and we have all these geopolitical concerns here, so that's what's adding to the selling this afternoon. There was really no rally today, we haven't been able to lift them, we haven't been able to hold, so everyone's just bailing out here, I think.

"From a technical standpoint, that break in the 200-day moving average on the Nasdaq is a big negative," he added. "There's no two ways about it."

All the indices are now close to flirting with their lowest closing levels of the year, set in late March, which were thought to be the bottom of a long-awaited correction in the bull market. Those lows are considered major support levels in a trading range that is more than a month old. For the Dow, that low is about 10,048, while the Nasdaq's is 1902 and the S&P's is 1108.