U.S. stocks extend gains on earnings optimism By: MarketWatch April 09, 2010 at 09:51 AM EDT U.S. stocks open higher Friday, extending Thursday's gains on hopes for the first-quarter earnings reports starting Monday to come in above analysts' estimates. Read More >> Related Stocks: Aetna Alcoa Caterpillar Chevron Corp Constellation Brands Dow Jones Industrial Average (EOD) Standard & Poors 500