WASHINGTON - The net worth of U.S. households climbed to a record high in the final quarter of last year, boosted mostly by gains on stocks, the Federal Reserve reported Thursday. Net worth — the difference between households' total assets, such as houses and bank accounts, and their total liabilities, such as mortgages and credit card debt, totaled $55.6 trillion in the October-to-December quarter. That marked a 2.5 percent growth rate from the third quarter, the previous quarterly record high. Stocks gains helped fuel the increase in net worth, although real-estate gains played a role, too. For all of last...