Bullish comments from Warren Buffett helped U.S. stocks end another good month on a high note on Monday, but uncertainty about oil prices could keep investors from pushing the market much higher.

A sign stocks may stall out was evident in the lackluster volume. Just 7.29 billion shares traded on the New York Stock Exchange, NYSE Amex and Nasdaq, well below last year's daily average of 8.47 billion.

The Dow Jones industrial average <.DJI> gained 95.89 points, or 0.79 percent, to 12,226.34. The Standard & Poor's 500 Index <.SPX> gained 7.36 points, or 0.56 percent, to 1,327.24. The Nasdaq Composite Index <.IXIC> gained 1.22 points, or 0.04 percent, to 2,782.27.

(Editing by Kenneth Barry)