China's $240 Billion Foreign Aid
It is however probably in China's best interest to end its policy of slow appreciation and allow faster appreciation. One reason is that it would better contain inflation. Another reason is that China is losing big from its accumulation of foreign exchange reserves. By for example investing in U.S. Treasuries they receive a lower interest in a currency that is depreciating, creating big losses. According to estimates made here, China loses as much as $240 billion per year by investing in loss creating assets like U.S. Treasuries.
This means that China is in effect giving away $240 billion to the rest of the world through its exchange rate interventions, making China the world's biggest foreign aid donor. It is true (assuming that the yuan really is undervalued or at least not significantly overvalued) that this is at this point more or less a sunk cost given that these asset purchases have been made. However, by ending foreign asset purchases it can stop the continued increase in losses. If it by contrast persists in these purchases, future annual losses will rise far above $240 billion.