The Nikkei stock index briefly plunged more than 5 percent on Monday amid surging crude oil futures due to concerns about an extended and escalating war in the Middle East.In the first 15 minutes of trading, the 225-issue Nikkei Stock Average fell 2,719.02 points, or 5.09 percent, from Friday to 50,654.05. The broader Topix index was down 171.96 points, or 4.71 percent, at 3,477.73.On the top-tier Prime Market, the main decliners were glass and ceramics product, transportation equipment and securities house issues.At 9 a.m., the dollar fetched 160.24-26 yen compared with 160.25-35 yen, topp…READ FULL ARTICLE