Tokyo stocks opened mixed Wednesday as selling to lock in gains after the Nikkei index ended at a record high the previous day was offset by buying of financial issues. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average fell 74.43 points, or 0.18 percent, from Tuesday to 41,505.74. The broader Topix index was up 2.82 points, or 0.10 percent, at 2,898.37. On the top-tier Prime Market, decliners were led by real estate and machinery issues, while insurance and marine transportation issues led gainers. At 9 a.m., the U.S. dollar fetched 161.31-34 yen compared with 161.26-36 ye…