* Crude oil slumps, but above $50 per barrel
* Priceline shares rally in premarket after results
* Jobless claims fall in latest week
* Dow down 20 pts, S&P down 2.75 pts, Nasdaq up 5.5 pts (Adds data, Wal-Mart results)
By Ryan Vlastelica
NEW YORK, Feb 19 (Reuters) - U.S. stock index futures pointed to a flat open on Wall Street Thursday, with major indexes near record levels, as investors continued to digest ongoing uncertainty over Greece.
Energy shares looked to be in focus with crude oil down 4.2 percent at $49.94 per barrel, as another big weekly build in U.S. crude inventories and possible rise in Saudi output fueled concerns about oversupply. Exxon Mobil fell 1.2 percent to $89.95 in premarket trading while Halliburton Co was off 2.2 percent to $43.43 and ConocoPhillips fell 2.2 percent to $66.25.
The commodity has rebounded 15 percent from a recent bottom hit in late January but is still down more than 50 percent from a June peak.
While the decline in energy prices is expected to spur consumer spending, it has severely hurt oil companies, with many cutting spending plans for 2015 in a bearish sign for economic growth prospects. Late Wednesday, Marathon Oil said it would cut its 2015 capital budget by 20 percent, the second cut of that magnitude since December.
While oil prices have been volatile of late, notching sharp swings in both directions, the broader market has been fairly quiet as investors await clarity on the situation in Greece. Over the past 14 sessions, the S&P 500 has moved an average of 21.06 points from its peak to its trough, down from an average of 31 points on Feb. 2. The CBOE Volatility index has fallen in five of the past six sessions.
Wal-Mart Stores fell 1 percent to $85.40 in premarket trading after the Dow component reported quarterly results and said it expects ongoing headwinds from currency exchange rates during 2015.
Priceline Group Inc jumped 8.3 percent to $1,216.49 in premarket trading after the online travel agency reported better-than-expected quarterly earnings.
In Europe, the German finance ministry rejected a new proposal from Athens for an extension of its bailout program, saying it fell short of the conditions set out by the country's euro zone partners.
On Wednesday, a Greek government spokesperson said the country aimed to conclude a deal with its euro zone partners "soon." U.S.-listed shares of the National Bank of Greece rose 3.3 percent to $1.56 before the bell.
In the latest economic data, initial jobless claims fell more than expected in the latest week, offering fresh evidence that the labor market was gathering steam.
Futures snapshot at 8:43 a.m.:
* S&P 500 e-minis were down 2.75 points, or 0.13 percent, with 138,958 contracts changing hands.
* Nasdaq 100 e-minis were up 5.5 points, or 0.13 percent, in volume of 24,814 contracts.
* Dow e-minis were down 20 points, or 0.11 percent, with 29,385 contracts changing hands. (Editing by Bernadette Baum)