Mart announced a bid to acquire a South African retailer Massmart Holdings for $4 billion. Shares of the world's biggest retailer fell almost 1 percent. The broader Standard & Poor's 500 index fell 6.51, or 0.6 percent, to 1,142.16. The technology-heavy Nasdaq composite index fell 11.45, or 0.5 percent, to 2,369.77.
