* Buyback, dividend hike, guidance lift Boeing, 3M, CVS
* Indexes: Dow up 0.4 pct, S&P up 0.3 pct, Nasdaq down 0.1 pct (Updates to afternoon)
By Caroline Valetkevitch
NEW YORK, Dec 16 (Reuters) - The Dow and S&P 500 were holding onto small gains in volatile trading Tuesday afternoon, helped by a rebound in energy shares and investor bets the Federal Reserve will be cautious in removing support in the face of a more fragile global economy.
But both indexes were well off their highs for the day, with consumer discretionary shares the biggest drag on the S&P, while the Nasdaq was lower. Shares of Amazon were down 2.5 percent.
The S&P 500 moved more than 40 points from its high of the day to its low.
Futures crumbled in early trading as the ruble neared 80 per U.S. dollar, down 21 percent. The Russian currency sharply pared its losses and was down about 3 percent, near 68 per dollar.
Brent crude fell as much as 4.2 percent but was last down 2.3 percent at $59.65 a barrel. U.S. crude, which fell as much as 4.1 percent, was last down 31 cents at $55.60.
Still the S&P energy index was up 1.6 percent, leading gains on the S&P 500, as investors snapped up beaten down shares. The index is down 15.6 percent for the year so far following a sharp selloff in oil prices since June.
"There were many, many stocks, especially in the energy sector that were just trading at absolutely ridiculous prices to their fair market valuation," said Paul Mendelsohn, chief investment strategist at Windham Financial Services in Charlotte, Vermont.
At 1:43PM the Dow Jones industrial average rose 64.46 points, or 0.38 percent, to 17,245.3, the S&P 500 gained 5.82 points, or 0.29 percent, to 1,995.45 and the Nasdaq Composite dropped 4.18 points, or 0.09 percent, to 4,600.98.
Chevron, up 2.6 percent, was leading the points advance in the sector. Chevron's forward price-to-earnings ratio was at 13.6 at the close on Monday, compared to the S&P 500's 16.1, meaning investors pay less for every dollar of Chevron's earnings than they do for the S&P 500 overall.
Among the top percentage gainers, Nabors Industries, up 7.6 percent, had a forward P/E of 8.6, while Denbury Resources' P/E was 8.9. Denbury rose 8.4 percent.
Market participants also said bets on the Federal Reserve's next move were giving stocks support. Fed officials will decide this week whether to make a critical change to their policy statement that would widen the door for interest rate hikes next year. In October, The Fed repeated that benchmark rates were unlikely to rise for a "considerable time."
CVS Health Corp rose 3.8 percent to $94.14 after issuing a strong 2015 forecast. 3M lifted its dividend and was the top points gainer on the Dow industrials with a 2.2 percent advance. Boeing, up 2.3 percent, was among the best performers after it raised its dividend and perked up its buyback program.
Advancing issues outnumbered declining ones on the NYSE by 1,841 to 1,188, for a 1.55-to-1 ratio; on the Nasdaq, 1,601 issues rose and 1,081 fell for a 1.48-to-1 ratio. (Additional reporting by Rodrigo Campos and Chuck Mikolajczak; editing by Chizu Nomiyama, Nick Zieminski and Meredith Mazzilli)