Stock market today: Dow, S&P 500, Nasdaq falter amid worries over frothy valuations

US stocks fell on Tuesday as doubts about high-running valuations preyed on investors sifting through the latest flurry of quarterly earnings. The tech-heavy Nasdaq Composite (^IXIC) led the morning's losses, sliding about 0.9%, in a slight recovery from steeper early losses. The benchmark S&P 500 (^GSPC) lost about 0.6%, while the Dow Jones Industrial Average (^DJI) also recovered from bigger losses to dip 0.2%. Wall Street is getting nervous that companies aren't performing well enough to justify thei ...