* Forest Labs surges after Actavis confirms acquisition
* Maker of Candy Crush files for U.S. IPO
* Futures up: Dow 21 pts, S&P 2.5 pts, Nasdaq 4 pts
NEW YORK, Feb 18 (Reuters) - U.S. stock index futures were slightly higher on Tuesday after Wall Street posted its biggest weekly percentage gains of the year, with investors looking towards a batch of economic data for clues on the health of the economy.
* U.S. stocks closed higher on Friday, with major indexes notching a second straight week of gains as investors shrugged off some weak economic data that was attributed to bad weather.
* U.S. markets were closed Monday for Presidents Day.
* Shares of Forest Laboratories Inc rocketed more than 35 percent in premarket trading after Actavis said it would acquire the specialty pharmaceuticals company in a massive cash and stock deal valued at about $25 billion.
* Coca-Cola Co reported an 8.3 percent fall in quarterly earnings, hurt by the separation of its bottling operations in Brazil and the Philippines. The stock was down 0.6 percent in premarket trading.
* S&P 500 e-mini futures rose 2.5 points and were in line with 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 rose 21 points and Nasdaq 100 futures added 4 points.
* Shares of BlackBerry Ltd rose 4.7 percent in premarket trading after hedge fund manager Dan Loeb's Third Point LLC disclosed a 10-million-share stake in the Canadian telecommunication and wireless equipment company.
* Empire State manufacturing survey, due at 8:30 a.m. EST (1330 GMT) is expected to show a reading of 9, down from 12.51 in January, according to a Reuters survey of economists. The housing market index is due at 10:00 a.m. EST.
* Mobile game maker King Digital Entertainment PLC, best known for the hit puzzle Candy Crush Saga, said it planned to raise up to $500 million in an initial public offering.