* Blackberry slumps after results
* Molycorp climbs after SEC investigation
* Futures up: Dow 23 pts, S&P 2.6 pts, Nasdaq 3.5 pts
By Chuck Mikolajczak
NEW YORK, June 28 (Reuters) - U.S. stock index futures advanced on Friday, putting the S&P on track for its first four-day gain since early April, as concerns eased over a premature pullback of central bank stimulus measures and following upbeat economic data from Japan.
* The S&P 500 has risen 2.6 percent over the past three sessions as economic data and comments from U.S. Federal Reserve officials soothed worries over an earlier-than-expected reining in of stimulative bond purchases by the Fed.
* Japanese data showed consumer prices stopped falling in May and labor demand was at its strongest in five years, though the Bank of Japan's time frame for achieving a 2 percent inflation target still appeared unlikely.
* U.S. economic data expected on Friday includes the June index of manufacturing activity from the Institute for Supply Management Chicago at 9:45 a.m. EDT (1345 GMT). Economists in a Reuters survey forecast a reading of 56.0, from 58.7 in May.
* Shortly after at 9:55 a.m. (1355 GMT), the Thomson Reuters/University of Michigan Surveys of Consumers final June consumer sentiment index is due. Economists surveyed by Reuters expect a reading of 82.8 compared with 82.7 in the preliminary June report.
* The benchmark S&P index had slumped as much as 4.8 percent in the days following a June 19 statement from the U.S. Federal Reserve, when Chairman Ben Bernanke said the Fed could start slowing its stimulative bond purchases later this year if growth was strong enough.
* The recent rally for the S&P 500 marks its best three-day performance since early January. The index is currently up 2.8 percent for the quarter and 13.1 percent for the year, though it is on track for its first monthly loss since October.
* S&P 500 futures rose 2.6 points and were above 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 gained 23 points, and Nasdaq 100 futures added 3.5 points.
* Investors can expect a surge of volume at the close Friday when Russell Investments is due to set the final update for the annual reconstitution of its indexes.
* U.S.-listed shares of Research in Motion plunged 16 percent to $12.16 in premarket trade after the BlackBerry maker posted first-quarter earnings.
* Molycorp Inc jumped 11.6 percent to $6.26 in premarket after the rare earths producer said the U.S. Securities and Exchange Commission has completed an investigation against the company and has not recommended any enforcement action.
* European shares pared gains on Friday, with trading expected to be subdued as investors avoid making large bets at the end of a volatile quarter.
* Asian shares rose for a third day, led by Tokyo's Nikkei index, to end the first half of the year up a barnstorming 31.5 percent.