"I think the market's just kind of drifting around a little bit," said JJ Kinahan, chief strategist at TD Ameritrade. "The volume's so light, I think it's the path of least resistance. There's less selling pressure on a given day because of the Fed coming out."
Stocks extended gains in afternoon trade, while Treasury yields spiked and the dollar held higher.
"In today's market it's hard to generalize because there are a fair amount of crosscurrents," said Paul Nolte, portfolio manager at Kingsview Asset Management. He's watching to see if the S&P 500 can hold above 2,000 in the near term.
The Dow Jones industrial average closed up about 230 points, or 1.4 percent, after earlier gaining as much as 273 points. The blue chip index held out of correction territory, within 10 percent of its 52-week high.
The S&P 500 and Nasdaq composite each gained more than 1 percent, both within 8 percent of their 52-week highs. In early trade, the Nasdaq dipped into negative territory.
The Russell 2000 closed up 1.06 percent, failing to hold out of correction mode.
"In a market that's been meandering this week in a wait-and-see mode, the positives in the market are coming from the commodity complex," said Art Hogan, chief market strategist at Wunderlich Securities. From the data, "your reading on the U.S. economy continues to be net positive."
Key morning reports on retail sales and industrial production missed expectations slightly.
"It's good economic news without forcing the Fed's hand at the end of this week," said Eric Lascelles, chief economist at RBC Global Asset Management.
"None look great in terms of their headline but the revisions (are positive)," he said.
Crude oil futures settled up 1.3 percent at $44.59 a barrel on the New York Mercantile Exchange. Earlier, U.S. crude oil pared gains after the White House said it does not support a move by the U.S. House of Representatives to repeal a 40-year-old ban on exports of crude oil.
The energy sector jumped more than 1 percent following the gains in oil.
"Oil prices are a little higher now so we'll get some help from there," said Peter Cardillo, chief market economist at Rockwell Global Capital.
As traders awaited a possibly historic decision on short-term interest rates, significant market moves were not expected ahead of the Fed meeting.
"Everything is coiling and waiting for Thursday," said John Caruso, senior market strategist at RJO Futures.
"The trading ranges are shrinking day by day as we move into Thursday," he said. "There's a lot of big cash positions out there."
The Dow closed down 62 points on Monday to post its narrowest intraday trading range since Aug. 18.
S&P 500 year-to-date (as of close Tuesday)
The Federal Open Market Committee could raise short-term interest rates for the first time in more than nine years at its two-day meeting, which begins Wednesday and culminates in a statement release and press conference Thursday.