* Stocks set to end the week lower
* Data on tap includes producer prices, consumer sentiment
* Futures down: Dow 12 pts, S&P 1.6 pts, Nasdaq 1.75 pts
By Leah Schnurr
NEW YORK, June 14 (Reuters) - U.S. stock index futures inched lower on Friday, with Wall Street set to rack up a loss for the week, as concerns linger over whether world central banks will prematurely rein in stimulus programs that have boosted equity markets this year.
Uncertainty over the longevity of monetary policy around the world has roiled markets recently and nerves were stretched further earlier in the week when the Bank of Japan decided to hold policy steady.
The prospect that the accommodative stance of central banks - particularly the Federal Reserve - could be pulled bank sooner than expected has prompted traders to rethink this year's bets that have been built around that support. Stocks have fallen during three of the past four days, and heading into Friday's session, the S&P 500 is down 0.4 percent on the week.
Attention is now focused on the Fed's policy-setting meeting next week. Investors will be looking for insight into how soon the central bank will wind down its monthly $85-billion bond purchase plan.
"Markets are looking at next week's Fed meeting to be the big driver in the short-term," said Kim Forrest, senior equity research analyst at Fort Pitt Capital Group in Pittsburgh.
"Bernanke has really increased the amount of transparency in the Fed's thinking," said Forrest. "This isn't going to be a jack-in-the-box surprise Fed, it's going to be a Fed that clearly indicates what it's going to do. That's why people are looking to this meeting in particular."
On the economic front, investors await data on producer prices, industrial production and consumer sentiment.
S&P 500 futures fell 1.6 points but 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 was off 12 points, and Nasdaq 100 futures lost 1.75 points.
Boeing Co is poised to launch a larger member of its 787 Dreamliner jetliner family to meet demand for long-haul travel within Asia and other long-haul routes, sources said.
Smith & Wesson Holding Corp's shares could get a boost after the gun maker raised its outlook for the fourth quarter.
Broadcast Music Inc (BMI), a songwriters' rights organization, is suing Pandora Media after the Internet radio company rejected a request to pay a higher license fee for playing songs across various devices.