KUALA LUMPUR, Malaysia (AP) - Asian stock markets were mixed Wednesday as investors remained cautious ahead of testimony from U.S. Federal Reserve Chairman Ben Bernanke. Bernanke's address to lawmakers in Congress later Wednesday could provide clearer guidance on when the Fed will start reducing its monetary stimulus. The Fed is spending $85 billion a month buying financial assets in the hope of keeping long-term borrowing rates low and stimulating the U.S. economy. The program has been a major driver of gains in stock markets as investors sought higher returns in a low interest rate world. China's Shanghai Composite Index fell 0.4 percent to 2,058.40 and Tokyo's Nikkei 225 dipped 0.4 percent to 14,535.51. Hong Kong's Hang Seng rose 0.2 percent to 21,355.90 and Seoul's Kospi added 1.2 percent to 1,889.50. There is partly caution ahead of Bernanke's testimony. I don't expect anything new. He is likely to reiterate that policies will remain accommodative for some time," said Mitul Kotecha, analyst with Credit Agricole CIB. Bernanke last week said the central bank would not ease its stimulus before the economy was ready and that the U.S. needs "highly accommodative monetary policy" - or low interest rates - for the foreseeable future. There is concern however, over disagreement among Fed officials about when the central bank should start scaling back its purchases of Treasurys and other assets. DBS analysts said in a report that as long as the U.S. recovery proceeds as expected, a reduction in the Fed's asset purchases will probably start with mortgage-backed securities later this year and that the stimulus could ideally end by mid-2014. It said Bernanke was likely to reassure markets that if the U.S. economy stumbles, the Fed could increase asset purchases again. In the U.S., the Dow Jones industrial average closed down 0.2 percent at 15,451.85 on Tuesday while the broader S&P 500 index ended an eight-day rally to fall 0.4 percent to 1,676.26, partly due to lackluster corporate earnings. Benchmark crude for August delivery was down 17 cents at $105.83 a barrel in electronic trading on the New York Mercantile Exchange. The contract fell 32 cents to settle at $106.00 on Tuesday. In currencies, the euro fell to $1.3141 from $1.3149 late Tuesday. The dollar rose to 99.33 yen from 99.21 yen.