Updated with closing prices.

Upgrades in the tech sector helped the Nasdaq on Friday, but the major stock indices recorded losses for the week amid falling oil prices, earnings warnings and an unexpected drop in consumer confidence.

The Dow Jones Industrial Average fell 36.65 points, or 0.5%, to 8146.52, and the S&P 500 shed 3.55 points, or 0.4%, to 879.13. The Nasdaq Composite, however, added 3.48 points, or 0.2%, to 1756.03.

JPMorgan Chase ( JPM) was the worst performer on the Dow, with a 3.8% loss. It was followed by Chevron ( CVX), down 2.7%, after an earnings warning.

Analyst adjustments to tech stocks, including upgrades to Novellus Systems ( NVLS) and Dell ( DELL), and an increased price target for Apple ( AAPL) helped to boost the Nasdaq.

(Click below for my interview with Charles Rotblut, senior market analyst with Zacks Investment Research, on what to expect out of this earnings season, including areas to check out and those to avoid.)

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But all three major indices were negative for the week, with the Nasdaq faring the worst. The Dow Jones Industrial Average gave up 1.6%, the S&P 500 lost 1.9%, and the Nasdaq shed 2.3% in the five-day session.

Both the Nasdaq and the Dow are at critical support levels, said Anu Sharma, managing director of the market intelligence desk at Nasdaq OMX. "Breaking those levels could cause another 4% to 5% decline in the market, which is why you're not seeing people move back into equities right now - people don't want to risk that right now."

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