Stocks crept higher at the open, as a pair of homebuilders planned a big merger and the government sought to help life insurers. The Dow inched up 25 points, and the S&P 0.6%, while the Nasdaq jumped 1.3%. Centex shares soared 28% on news that it would merge with Pulte Homes to create the world’s largest homebuilder. Concern about earnings still lingered however—Ryder dropped 11% after warning that its earnings would disappoint. (More earnings reports stories.)