U.S. stocks closed down sharply Tuesday, after a volatile day of trading. In U.S. economic news, investors are becoming increasingly worried that central banks might start paring back their historically unprecedented levels of bond buying. U.S. investors seem as if they are going to take a wait and see approach until next week, when Federal Reserve (Fed) Chairman Ben Bernanke holds his quarterly press conference. Bernanke is expected to give investors some hints as to when the Fed’s easing might stop or slow down. In international economic news, Japan’s central bank spooked investors early in the day by leaving its monetary policy unchanged. Many investors had expected further stimulus. Prime Minister Shinto Abe has been trying to weaken the yen to boost experts. But “Abenomics” does not seem to be working lately. In corporate news, Lululemon shares tanked after the yoga wear maker announced that chief executive Christine Day is stepping down. Shares of Sprint Nextel rose after SoftBank, Japan’s third-largest wireless carrier, increased its takeover offer. Shares of aircraft maker Boeing slipped after the company trimmed its 20-year forecast for widebody jet demand, even as it raised its forecast for single-aisle jets. Google announced that it would acquire mapping company Waze, but did not disclose a price tag. The dollar lost ground against the euro, the pound, and the yen. Light sweet crude oil for July delivery dropped 39 cents to $95.38 a barrel on the New York Mercantile Exchange. Gold futures fell $9.00 to $1,377.00 an ounce. The Dow Jones industrial average lost 116.57, or 0.76 percent, to 15,122.02. The broader Standard & Poor’s 500 index fell 16.68, or 1.02 percent, to 1,626.13. The technology-heavy Nasdaq composite index dropped 36.82, or 1.06 percent, to 3,436.95.