Chinese banks purchased forex worth 155.9 billion U.S. dollars last month while selling a total of 119.9 billion U.S. dollars, creating a surplus of 35.9 billion U.S. dollars, data from the nation's top forex regulator showed on Friday. It marked the third month of surplus since August, after a deficit in June and July. Analysts attributed the surplus to growth of economy appreciation of Renminbi and delay of the U.S. Federal Reserve's tapering off of quantitative easing (QE3). Foreign exchange transactions are a major cause of fluctuation in China's foreign exchange reserves, and the October surplus indicates a slowing outflow of foreign capital. In the January - October period, forex purchases stood at 1.53 trillion U.S. dollars, with sales of 1.33 trillion U.S. dollars, a surplus of 202.6 billion U.S. dollars.