UPDATE 2-Russia Vimpelcom earnings soar, but miss fcast

(Adds details, quotes, share price, analysts' comments)

MOSCOW, March 12 (Reuters) - Vimpelcom (VIP.N: Quote, Profile, Research), Russia's No.2 mobile phone operator, on Wednesday posted an 86 percent jump in fourth-quarter net profit but fell short of market expectations and saw its shares fall by about 5 percent.

The net profit, in U.S. GAAP terms, was up to $368.1 million against an average forecast of $401.5 million in a Reuters poll of nine analysts.

Operating income before depreciation and amortisation (OIBDA) rose 33 percent to $918.4 million, also well below the market expectation of $996.4 million.

The OIBDA margin fell to 45.7 percent from 47.5 percent a year ago, below analysts' forecasts of about 49.3 percent.

"This shortfall to expectations was primarily due to higher than expected expenses related to stock-based compensation for management, which is a non-cash and non-recurring item," analysts from Uralsib Bank wrote in a results review.

Vimpelcom's Chief Executive Officer Alexander Izosimov told reporters the expenses amounted to $118.7 million in the fourth quarter, up by $78.2 million from the third quarter and by $94.5 million over the fourth quarter of 2006.

"As the share price rose by more than 50 percent in the fourth quarter, allocations to stock-option programmes increased. This has no burden on the company's cash flow," Izosimov said.

Without those expenses, Vimpelcom's OIBDA margin would have exceeded 50 percent, the company said.