Tokyo stocks opened nearly flat Monday as a weak yen against the dollar lifted export-oriented issues, while sentiment was weighed down by speculation over potential aggressive monetary tightening by the U.S. Federal Reserve ahead of the bank’s policy meeting later in the week. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average fell 19.33 points, or 0.07 percent, from Thursday to 26,828.57. Japanese financial markets were closed Friday for a national holiday. The broader Topix index was up 1.28 points, or 0.07 percent, at 1,900.90. On the top-tier Prime Market, decliners we…