Days after China posted its biggest trade deficit in a decade, the country's central bank says it will take a step back from intervention, and encourage the value of the yuan currency to be set by the market. The yuan has appreciated 30 percent against the U.S. dollar since 2005. And, at $3.2 trillion, China has the world's largest foreign currency reserves. But it's struggled to manage them effectively. Some of those reserves are invested in the struggling euro zone.