* IMF lowers growth outlook for 2015 and 2016
* Oil lower on concerns of lower demand ahead
* FXCM plummets 90 percent, details loan agreement
* Indexes down: Dow 0.7 pct, S&P 0.5 pct, Nasdaq 0.5 pct (Updates to afternoon trading)
By Ryan Vlastelica
NEW YORK, Jan 20 (Reuters) - U.S. stocks fell on Tuesday after the International Monetary Fund lowered its growth forecasts for 2015 and 2016, though the move spurred hopes that central banks would take more aggressive policy stances to accelerate economic improvement.
The lower forecasts implied less demand for fuel through 2016, contributing to another fall in crude oil, which pressured energy names despite some bullish results from major names.
The IMF projected growth of 3.5 percent this year and 3.7 percent next year, both forecasts are down by 0.3 percentage points. The IMF advised advanced economies to maintain accommodative monetary policies to avoid increases in real interest rates as cheaper oil increases deflation risk.
"This absolutely raises the odds that we'll see more central bank action. The upside to seeing less international growth is that it is now very unlikely the Federal Reserve will raise interest rates mid-year," said Paul Nolte, portfolio manager at Kingsview Asset Management in Chicago.
The European Central Bank is expected to announce on Thursday a program of bond buying to boost the region's flagging economy.
"If we don't see something out of the ECB, that will really increase volatility," Nolte said.
U.S. crude futures fell 3.2 percent to $47.13 per barrel, keeping the commodity - which is down more than 55 percent since June - near its lowest level since 2009.
Halliburton Co and Baker Hughes Inc warned that a fall in drilling activity would hurt results in 2015, though the companies also reported better-than-expected fourth-quarter profits. Halliburton rose 0.7 percent to $39.39 while Baker rose 0.7 percent to $56.94.
Johnson & Johnson fell 3.6 percent to $100.33 after adjusted earnings beat expectations but revenue missed forecasts.
Morgan Stanley reported a drop of 81 percent in revenue from trading fixed-income securities, currencies and commodities, though earnings rose on a sharp drop in legal costs. Shares fell 1.3 percent to $34.42.
FXCM Inc plummeted 89 percent to $1.33 on volume of 66 million shares, its most active day ever and the most active name on the New York Stock Exchange. The retail foreign exchange broker on Friday said it would get a $300 million loan from Leucadia National Corp to keep operating after losing millions from a recent surge of the Swiss franc. Late Monday, FXCM provided details on the terms of the loan.
Adding to the cautious tone in the market, a Ukrainian military spokesman said that soldiers came under attack from Russian regular forces in the north of the conflict zone in eastern Ukraine.
At 12:38 p.m. (1738 GMT) the Dow Jones industrial average fell 118.83 points, or 0.68 percent, to 17,392.74, the S&P 500 lost 10.6 points, or 0.52 percent, to 2,008.82 and the Nasdaq Composite dropped 20.68 points, or 0.45 percent, to 4,613.70.
Declining issues outnumbered advancing ones on the NYSE by 2,115 to 915, for a 2.31-to-1 ratio; on the Nasdaq, 1,868 issues fell and 810 advanced for a 2.31-to-1 ratio favoring decliners.
The S&P 500 was posting 45 new 52-week highs and 17 lows; the Nasdaq Composite was recording 52 new highs and 90 lows. (Editing by Chizu Nomiyama and Nick Zieminski)