NEW YORK (Reuters) – U.S. stocks were little changed on Monday as another day of persistently below-average volume suggested investors weren't willing to chase gains that carried stocks to 2 1/2-year highs last week. Equities were coming off two straight weeks of gains, although light trading volume undercut the bullish sentiment. "We've been setting new highs on low volume, which suggests the rally is on thin ice," said Tom Mangan, a portfolio manager who helps oversee $2.4 billion at James Investment Research Inc in Xenia, Ohio. He said a correction was likely. President Barack Obama proposed a federal budget that...