The S&P 500 hit a new milestone as the market advanced Monday in another volume-challenged session. The S&P 500 climbed 0.5% as it traded above the 2000 level for the first time. It closed a little below the 2000 level. The Nasdaq, which hit a fresh 14-year high, rose 0.4%. Both indexes were up as much as 0.7% at their session highs. On a slightly down note, the Nasdaq snapped a recent trend of closing near its session highs.