Asian shares are mixed following a retreat on Wall Street, as the U.S. Treasury Department's plan to expand government debt buybacks appeared to have only limited capacity to calm markets. U.S. futures edged higher. The Treasury Department said Wednesday that it will at least double the size of its planned purchases of longer-term government debt. Treasury Secretary Scott Bessent signaled Thursday the repurchase program could be larger. The announcement had temporarily brought down Treasury yield levels but by early Friday the U.S. 10-year Treasury yield is already back to levels early this week. That's weighing on share prices. On Thursday, the S&P 500 lost 0.9%. The Dow industrials fell 1.3%, and the Nasdaq composite dropped 1%.