HONG KONG—Asian stocks slipped on Wednesday, following a mixed Wall Street session as the region’s investors positioned their portfolios for the new year and continued to grapple with increasing global numbers of Omicron coronavirus cases. MSCI’s broadest index of Asia-Pacific shares outside Japan lost 0.25 percent, after six sessions of gains, following volatile U.S. trade. There were losses in Hong Kong, down 0.6 percent hurt by declines in mainland tech stocks while Chinese blue chips shed 0.25 percent. Japan’s Nikkei slid 0.58 percent Wednesday after hitting a one-month high on Tuesday. But in Australia, the ASX 200 was up 1 percent early in the session even though the country’s most populous state New South Wales announced 11,201 new coronavirus cases. Volatile markets are common in late December as fund managers prepare to rule off their books for the year and holidays thin trading volumes in some major markets like Australia. …