China rattled global financial markets by devaluing its currency in what it said was an effort to make its exchange rate more market-oriented. The yuan's value declined 1.9 percent on Tuesday, its biggest one-day drop in a decade, and dropped a further 1.6 percent on Wednesday. The move could help Chinese companies by making their products less expensive in global markets. U.S. stocks sank, partly on fears about a worsening economic slowdown in China.