U.S. stock indexes are drifting between small gains and losses in early trading as investors continue to watch for news from Greece and the Federal Reserve.

The Dow Jones industrial average slipped 21 points, or 0.1 percent, to 18,136 as of 9:35 a.m. Eastern time Tuesday.

The Standard & Poor's 500 was little changed at 2,109. The Nasdaq slipped 10 points, or 0.2 percent, to 4,950.

European markets were mostly unchanged, except in Greece, where stocks rose sharply after the government submitted a list of reforms aimed at winning approval for extended rescue loans.

Home Depot jumped 4 percent after beating earnings estimates, raising its dividend and announcing a share buyback.

Traders will be closely watching later in the day as Federal Reserve Chair Janet Yellen delivers remarks to Congress.