Stocks closed near session lows Friday, with all three major averages posting their worst weekly drop this year, as investors were cautious ahead of the weekend amid fears over the euro zone and euphoria over Facebook's trading debut fizzled.

Facebook eked out a tiny gain after fighting to stay in positive territory in the final hour of trading. The stock surged more than 10 percent out of the gate after pricing at $38 a share, becoming the largest Internet IPO in history. (Read More: Was the Facebook Deal Overhyped? )

Over 578 million Facebook shares exchanged hands during the regular trading session, easily surpassing GM's first-day record trading volume of 458 million shares by 3pm ET. Facebook's trading action accounted for almost 22 percent of the Nasdaq's volume today.

The Dow Jones Industrial Average fell 73.11 points, or 0.59 percent, to close at 12,369.38, logging its 12th down day in the last 13 sessions for the first time since October 1974.

The S&P 500 dropped 9.64 points, or 0.74 percent, to end at 1,295.22, slumping below the key 1,300 level for the first time since mid-January. The Nasdaq erased 34.90 points, or 1.24 percent, to finish at 2,779.79.