Worsening tensions in Ukraine are sending stock indexes lower, overshadowing an encouraging report on U.S. economic growth.
Ukraine's president said Russian forces have entered his country. He called an emergency meeting of his nation's security council.
Several retailers fell after releasing results or outlooks that disappointed investors. Williams-Sonoma plunged 11 percent and Abercrombie & Fitch fell 5 percent.
The Dow Jones industrial average fell 51 points, or 0.3 percent, to 17,071 as of noon Eastern time Thursday. The Dow is coming off three days of gains.
The Standard & Poor's 500 index fell four points, or 0.2 percent, to 1,995.
The Nasdaq composite fell 11 points, or 0.3 percent, to 4,558.
Bond prices rose. The yield on the 10-year Treasury note fell to 2.34 percent.