U.S. stocks edged up in a volatile session on Thursday, with the Dow and S&P 500 hitting fresh record closing highs on an indication that the European Central Bank would take more policy action if needed to boost a struggling euro zone economy.

Major indexes fluctuated between positive and negative territory throughout the day. Cyclical shares, ones tied to the pace of economic growth, were among the strongest. But weak results from Qualcomm (QCOM.O) pressured chipmakers.

ECB President Mario Draghi indicated support for additional measures to bolster the euro zone economy if necessary and said the ECB governing council was unanimous in its commitment to using unconventional measures.

The defensive telecom .SPLRCL and utilities .SPLRCU sectors were the weakest on the day, off 0.8 and 1.8 percent, respectively. Industrial shares .SPLRCI rose 1.1 percent as the strongest sector of the day.

Draghi "brought more clarity but there's still more to come out, and it isn't healthy to focus on hopes for stimulus instead of fundamentals," said Michael O'Rourke, chief market strategist at JonesTrading in Greenwich, Connecticut.

Qualcomm Inc (QCOM.O) pressured the tech sector, slumping 8.6 percent to $70.58 a day after it said an antitrust investigation and problems collecting royalties could harm its business in China next year. Orbitz Worldwide (OWW.N) fell 9.2 percent to $7.70 following its results.

Genworth Financial (GNW.N) plummeted 38.5 percent to $8.66 in heavy trading, its biggest one-day drop since November 2008 during the financial crisis. Tom McInerney, Genworth's chief executive, said he was "very disappointed" by the results of its U.S. life insurance division.

Whole Foods Market Inc (WFM.O) jumped 12.2 percent to $44.85 after its results beat expectations on Wednesday, boosted by gains in market share and new product launches. The stock notched its biggest one-day advance since May 2013.

The Dow Jones industrial average .DJI rose 69.94 points, or 0.4 percent, to 17,554.5, theS&P 500 .SPX gained 7.64 points, or 0.38 percent, to 2,031.2 and the Nasdaq Composite.IXIC added 17.75 points, or 0.38 percent, to 4,638.47.

About 6 billion shares changed hands on U.S. exchanges, below the 7.3 billion average for the last five sessions.

NYSE advancing issues outnumbered declining ones on the NYSE by 1,730 to 1,327, for a 1.30-to-1 ratio on the upside; on the Nasdaq, 1,557 issues rose and 1,121 fell for a 1.39-to-1 ratio favoring advancers.

The benchmark S&P 500 index posted 72 new 52-week highs and three new lows; the Nasdaq Composite recorded 118 new highs and 61 new lows.