US STOCKS-Wall St falls as Greece crisis unresolved; energy shares dip

* Greece talks suffer setback after IMF quits

* U.S. consumer sentiment surges in June

* Next (Other OTC: NXGPF - news) week's Fed policy meeting adds to investor caution

* Twitter (Xetra: A1W6XZ - news) rises after CEO quits abruptly

* Indexes down: Dow 0.8 pct, S&P 0.7 pct, Nasdaq 0.6 pct (Updates to close)

By Caroline Valetkevitch

June 12 (Reuters) - U.S. stocks fell on Friday as Greek debt talks hit a stalemate and as concern over how soon the Federal Reserve might raise interest rates kept investors cautious.

Energy shares dropped as oil prices fell for a second straight day. The energy index, down 1.2 percent, led the day's decline, followed by a 1.1 percent drop in the healthcare index.

Upbeat consumer sentiment and other data added to views the economy may be regaining momentum, which increased anxiety for investors ahead of next week's Federal Open Market Committee meeting, the U.S. central bank's last meeting before September.

Also of concern, a day after the International Monetary Fund quit bailout talks with Greece, EU officials said they had held their first formal discussions on the worst-case scenario for the country.

"It's the Greek situation again, and that's been played out on a day-to-day basis, where you had a huge rally followed by a decline, predicated on whether they are coming closer or moving further from a resolution over this situation," said Mark Luschini, chief investment strategist at Janney Montgomery Scott in Philadelphia.

The Dow Jones industrial average fell 140.53 points, or 0.78 percent, to 17,898.84, the S&P 500 lost 14.75 points, or 0.7 percent, to 2,094.11 and the Nasdaq Composite dropped 31.41 points, or 0.62 percent, to 5,051.10.

For the week, the Dow was up 0.3 percent, the S&P 500 was up 0.1 percent, while the Nasdaq Composite fell 0.3 percent, its third straight week of declines.

U.S. consumer confidence surged in early June. The University of Michigan's consumer sentiment index rose to 94.6 from 90.7 in May.

The upbeat report capped a week of strong economic data and was the latest indication that growth was regaining momentum after a sluggish start to the second quarter.

That added to investor caution, "particularly in light of the fact that we're just days ahead of the Fed meeting," Luschini said.

Higher rates will tighten the flow of easy money. Economists and top Wall Street banks expect the Fed to raise rates in September, in what could be its first hike in almost a decade.

Twitter Inc shares were up 0.2 percent at $35.90, a day after Chief Executive Officer Dick Costolo said he was stepping down.

Among the biggest decliners in health care, shares of Eli Lilly ended down 2.7 percent at $84.21. It hit its low for the session and volume spiked after Reuters reported the Alzheimer's Association may not offer an early look at trial data on an experimental drug from Eli Lilly.

News (Other OTC: NWSAL - news) of the impending release had led to a jump in the company's shares. Eli Lilly's stock had gained 10.3 percent from Monday's close to Thursday's finish.

Declining issues outnumbered advancing ones on the NYSE by 1,945 to 1,075, for a 1.81-to-1 ratio on the downside; on the Nasdaq, 1,586 issues fell and 1,146 advanced for a 1.38-to-1 ratio favoring decliners.

The benchmark S&P 500 index posted five new 52-week highs and eight new lows; the Nasdaq Composite recorded 73 new highs and 28 new lows.

About five billion shares changed hands on U.S. exchanges, compared with the 6.1 billion daily average for the month to date, according to data from BATS Global Markets. (Editing Meredith Mazzilli and James Dalgleish)