U.S. markets closed mixed Tuesday with policymakers at the Federal Reserve headed into a two-day meeting in Washington.

The start of the Open Market Committee meeting often puts investors into a two-day holding pattern as they wait for critical news on the central bank's lending rate decisions.

Stocks retreated early, but railroad shares surged 11.45 percent after billionaire investor Warren Buffett said he would buy Burlington Northern Santa Fe for $44 billion.

By close, the Dow Jones industrial average lost 0.18 percent, 17.53 points, to 9,771.91. The Standard & Poor's 500 index added 0.24 percent, 2.53, to 1,045.41. The Nasdaq composite index rose 0.4 percent, 8.12, to 2,057.32.

On the New York Stock Exchange, 1,841 stocks advanced and 1,185 declined on a volume of 5.4 billion shares traded.

The benchmark 10-year U.S. Treasury fell 12/32 to yield 3.469 percent.

The euro fell to $1.4718 from Monday's $1.4766. Against the yen, the dollar fell to 90.30 yen from Monday's 90.35 yen.

In Japan, the Nikkei 225 index lost 2.31 percent, 231.79, to 9,802.95.

In Britain, the FTSE 100 index lost 1.32 percent, 67.29, to 5,037.21.