U.S. stock indexes opened lower on Monday amid concerns about higher interest rates, while comments from a Russian official eased worries about a possible invasion on Ukraine. The Dow Jones Industrial Average fell 43.56 points, or 0.13 percent, at the open to 34,694.50. The S&P 500 opened lower by 6.03 points, or 0.14 percent, at 4,412.61, while the Nasdaq Composite dropped 22.19 points, or 0.16 percent, to 13,768.97 at the opening bell.