Just because China is burning through its reported foreign-exchange reserves more slowly doesn't mean it's losing its commitment to prop up the yuan.

The People's Bank of China and local lenders increased their holdings in onshore forwards to $67.9 billion in August, positions that would boost China's currency against the dollar. The amount is five times more than the average in the first seven months, PBOC data show. The positions are part of a three-stage process to support the currency without immediately draining reserves, according to China Merchants Bank Co. and Goldman Sachs Group Inc.

Standard central bank intervention to support a currency generally involves selling dollars and buying the home tender. In this case, China's large state banks borrowed dollars in the swap market, sold the U.S. currency in the cash spot market and used forward contracts with the central bank to hedge those positions.