* IBM, Intel fall after results
* SXC Health Solutions to buy Catalyst Health
* 22 S&P 500 companies due to report earns Wed
* Futures off: Dow 38 pts, S&P 3.4 pts, Nasdaq 9 pts
NEW YORK, April 18 (Reuters) - U.S. stock index futures dipped on Wednesday after the S&P 500 tallied its biggest gain in a month and ahead of another round of corporate earnings.
The benchmark S&P on Tuesday climbed 1.55 percent, its biggest percentage gain since March 13, after Coca-Cola Co led a round of solid earnings reports and after concerns eased over the euro zone debt crisis.
"What we've seen lately is when we see one and a half percent moves here, up or down, the markets tend to take a pause the next day, as opposed to snapping back that one and a half percent the other way," said Keith Bliss, senior vice president at Cuttone & Co in New York.
According to Thomson Reuters data, 22 companies in the S&P 500 were expected to report results on Wednesday. Including American Express Co, Qualcomm Inc and eBay Inc .
Of the 39 S&P 500 companies reporting earnings before Tuesday's opening bell, 74.4 percent beat estimates.
International Business Machines Corp shed 2.4 percent to $202.50 in premarket trade after reporting quarterly profit late Tuesday that beat expectations but revenue missed estimates.
"If we get declining sales and revenue across the board in these companies that are reporting in the first quarter, then we really need to take a pause and try to figure out what the proper valuation for the stock market is, and I'm not sure the proper valuation is up at these levels right now," said Cuttone's Bliss.
Intel Corp dropped 3.2 percent to $27.55 premarket after the chipmaker said late Tuesday sales would accelerate in the second half of the year, but the costs of upgrading its chipmaking factories were temporarily hurting margins.
S&P 500 futures fell 3.4 points and were below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures lost 38 points, and Nasdaq 100 futures declined 9 points.
BlackRock Inc, the world's largest asset manager, said first-quarter profits were steady, bolstered by strong inflows into its popular iShares exchange-traded funds.
Halliburton Co advanced 1.4 percent to $33.10 in premarket after the world's second-largest oilfield services company reported higher quarterly profits as North American revenue reached a record high.
Diversified U.S. manufacturer Textron Inc quadrupled its quarterly profit, helped by a strong recovery in demand for business aircraft and helicopters. Textron shares gained 1.3 percent to $28 premarket.
Nestle SA, the world's biggest food group, is near a deal to buy Pfizer Inc's infant nutrition business for up to $10 billion to boost its China business and extend its lead in the baby formula milk sector, sources said.
SXC Health Solutions Corp will buy pharmacy benefit manager Catalyst Health Solutions Inc for about $4.4 billion. Catalyst shares jumped 32.2 percent to $84 and U.S.-listed shares of SXC climbed 8.5 percent to $87.10.
Berkshire Hathaway Inc Chief Executive Warren Buffett said he has stage 1 prostate cancer but his condition "is not remotely life-threatening or even debilitating in any meaningful way."
European shares fell 0.6 percent as losses in utilities outweighed strength in miners.
Asian shares rose as firm demand at a Spanish debt sale and positive U.S. corporate earnings boosted investor confidence in riskier assets.