KELVIN CHANHONG KONG (AP) â¿¿ Asian stocks mostly drifted lower Monday as investors' growing concerns about the shaky global economy overpowered any remaining optimism over central bank stimulus efforts. Crude oil tumbled while the dollar rose against the euro but fell against the Japanese yen. Tokyo's Nikkei 225 index dropped 0.4 percent to 9,070.78 and Seoul's Kospi index shed 0.2 percent to 1,999.18. Hong Kong's Hang Seng was down less than 0.1 percent to 20,724.17 while Sydney's ASX S&P 200 fell 0.4 percent to 4,388.60. Benchmarks in Singapore and Indonesia also fell. Strategists at Credit Agricole CIB wrote in a research note that the "euphoria emanating" from recent moves by the Federal Reserve, European Central Bank and Bank of Japan to stimulate growth is "fading quickly." "The reality of weak growth and underlying structural tensions is coming back to haunt markets." The Fed vowed in mid-September to buy billions in mortgage securities each month until the economy improves in a third round of what is known as quantitative easing, or QE3. The ECB and Bank of Japan followed with their own renewed bond-buying plans. "There is this struggle between optimism towards QE3 and the concern about the global economic slowdown," said Louis Wong, a director at Phillip Securities in Hong Kong. "So investors are weighing the easing measures of central banks and the health of the global economy." China's Shanghai Composite Index rose 0.3 percent to 2,032.44, reversing losses earlier in the day. However, the benchmark is still at its lowest point since January 2009. Chinese stocks are being hurt by a dispute between China and Japan over disputed islands that has heightened tensions between Asia's two biggest economies. They're also under pressure as investors worry about what Chinese authorities will do to restart growth amid the country's economic slowdown. Wong said it's unlikely that Chinese authorities will unveil any major stimulus measures ahead of the National Day holiday next week or an expected but still unscheduled Communist Party meeting to hand over power to a next generation of leaders.