Wall Street’s main indexes opened higher on Wednesday after modest initial sanctions by Western nations on Moscow, with investors keeping a close watch on the fast-moving developments in the Russia-Ukraine crisis. The Dow Jones Industrial Average rose 84.36 points, or 0.25 percent, at the open to 33,680.97. The S&P 500 opened higher by 20.17 points, or 0.47 percent, at 4,324.93, while the Nasdaq Composite gained 130.23 points, or 0.97 percent, to 13,511.75 at the opening bell.