US STOCKS-Wall St edges higher, on track for third weekly gain

* Priceline and Hewlett-Packard both beat expectations

* Groupon (NasdaqGS: GRPN - news) shares tumble after forecasting loss

* Existing home sales fall to 18-month low in Jan

* Indexes up: Dow 0.2 pct, S&P 0.2 pct, Nasdaq 0.3 pct

By Ryan Vlastelica

NEW YORK (Frankfurt: HX6.F - news) , Feb 21 (Reuters) - U.S. stocks edged higher on Friday, with the S&P 500 within grasp of record levels in the wake of strong results at Priceline, though investors found little reason to push shares solidly higher following a recent rally.

Traders continued to watch the political situation in Ukraine, with EU mediators expecting an agreement between Ukraine's pro-European opposition and Russian-backed President Viktor Yanukovich, though the former was seeking last-minute changes to the deal.

Geopolitical concerns may take on a bigger role next week, when there will be few U.S. earnings and data releases to otherwise drive trading.

A report showed existing home sales fell more than expected to an 18-month low in January, the latest metric to indicate softness, though many analysts pin the weakness to weather instead of worsening fundamentals.

"We think the market is fairly valued, and there's reluctance to get excited at these levels, even though stocks remain the best bet on a long-term basis," said Malcolm Polley, president and chief investment officer of Stewart Capital Advisors in Indiana, Pennsylvania.

Priceline.com Inc jumped 3.2 percent as one of the S&P 500's biggest gainers, rising to $1,324.08 a day after reporting results that beat expectations.

Hewlett Packard Co (NYSE: HPQ - news) also reported results that topped expectations, and the computer maker also raised its 2014 profit view, though shares dipped 1.3 percent to $29.79.

The Dow Jones industrial average was up 33.06 points, or 0.20 percent, at 16,166.29. The Standard & Poor's 500 Index was up 3.83 points, or 0.21 percent, at 1,843.61. The Nasdaq Composite Index was up 10.70 points, or 0.25 percent, at 4,278.24.

For the week, the Dow is up less than 0.1 percent, the S&P 500 is up 0.3 percent and the Nasdaq is up 0.8 percent. All three indexes are gunning for a third week of advances, and the S&P is 0.2 percent away from an all-time high of 1,848.38 reached Jan. 15.

In company news, Groupon Inc slumped 16 percent to $8.62 a day after unexpectedly forecasting a quarterly loss, even as it reported revenue that was ahead of expectations.

Pharmacy benefit manager Express Scripts Holding Co late Thursday forecast 2014 earnings in line with Wall Street expectations and said it expects long-term earnings growth of up to 20 percent per year. Shares fell 3.9 percent to $74.10.

Tesla Motors Inc Chief Executive Elon Musk told Bloomberg TV that the company has had "conversations" with Apple (TLO: AP-U.TI - news) Inc, responding to speculation that the iPhone and iPad maker had shown interest in the electric car company. Musk declined to describe the talks, though he said it was "very unlikely" that Tesla would be bought by any company. Shares were up 0.7 percent at $211.45.