U.S. stocks open mixed amid Greek uncertainty

U.S. stocks opened mixed on Friday as investors were assessing the unfolding Greek debt crisis.

In the absence of major economic reports, investors shifted their focus to the Greek debt situation.

Eurozone leaders will hold an emergency summit on next Monday to try to avert a Greek default. This comes after a crucial meeting of the euro zone's finance ministers ended without an agreement over the Greece debt issue on Thursday.

"No agreement is in sight over Greece debt deal," Dutch Finance Minister and Eurogroup President Jeroen Dijsselbloem told press after Euro zone finance ministers' meeting in Luxembourg.

On June 30, the extension of Greece's second bailout expires, and on the same day Athens needs to repay some 1.5 billion euros (1.69 billion U.S. dollars) of loan installments to the International Monetary Fund.

U.S. stocks surged on Thursday, with the Nasdaq Composite Index surpassing its dotcom bubble peak set in March 2000, as investors digesting Federal Reserve Chair Janet Yellen's dovish tone on rate hikes.

The tech-heavy Nasdaq touched a new intraday high of 5,143.32 points on Thursday, breaking the 5,132.52 record it set on March 10, 2000.

Shortly after the opening bell, the Dow Jones Industrial Average fell 31.03 points, or 0.17 percent, to 18,084.81. The S&P 500 edged down 2.01 points, or 0.09 percent, to 2,119.23. The Nasdaq Composite Index added 5.73 points, or 0.11 percent, to 5,138.68. Endi