Chief Executive Gerhard Roiss is leaving nearly two years ahead of schedule in June 2015, followed by Chairman Rudolf Kemler in October. With no successors yet named, investors believe decision-making at OMV has ground to a halt just as energy prices plunge due to a global glut.

"The strategy is unclear," said Bernhard Ruttenstorfer, fund manager at Ringturm, which is OMV's sixth-biggest investor, according to Thomson Reuters Data. "As far as the big picture is concerned, we don't expect decisions before the new management starts."

A company spokesman declined to comment on investors' concerns, reflected in OMV's share price which hit a two-year low on Monday. The stock has lost more than a third this year, badly lagging a European oil and gas index <.SXEP> which has fallen around 13 percent.

OMV, which is 31.5 percent Austrian state-owned, has promised to come up with a new downstream division at the start of next year, combining weak gas and trading operations with its traditional refining and marketing businesses.

However, no details have yet emerged following October's announcement of the top-level departures, which company insiders say were due to boardroom infighting.

OMV had focused for years on Austria and then Romania, gradually expanding as far afield as Turkey, Yemen and Libya. Roiss, a marathon runner who after two decades at OMV became CEO in 2011, placed his bets on exploration and gas, shifting away from refining and marketing.

But oil prices have fallen around 40 percent since June to five-year lows, forcing OMV to curb its 3.9 billion euro ($4.9 billion) annual investments and warn it might not reach its output goal of 400,000 barrels of oil equivalent per day by 2016.

"A new strategy should make clear whether the strong focus will stay on exploration," Ruttenstorfer said.

As prices fell the gas and power division contributed only 0.04 percent of 2013 operating profit, down from almost 10 percent in 2011. OMV has not listed any practical consequences of folding the gas assets into the new downstream division, apart from the exit of gas business head Hans-Peter Floren, who insiders say had fallen out with Roiss.

The company has not excluded selling gas assets.

PIPELINE PROJECTS

Roiss's strategy had in part depended on the Nabucco pipeline project to bring Azeri gas to Austria, bypassing Russia. This would have boosted OMV's gas business, including its ailing trading platform.

Last year's decision by partners in a major Azeri gas development to opt for a rival project killed Nabucco but in February Roiss still forecast "profitable growth".

The European Commission has also called into question plans for the South Stream pipeline project which would bring Russian gas to OMV's Baumgarten hub in Austria.

Stung by supply disruptions in Libya and Yemen, he bet on more reliable but expensive production in the North Sea, buying assets from Norway's Statoil [STAT.UL] for $2.65 billion last year to boost output.

"All big players have been getting out of the North Sea or thinking about it, but OMV goes in," said Peter Oppitzhauser, head of oil and gas research at Kepler Cheuvreux. "OMV has a tendency to stick for too long to a target and doesn't communicate in time that there might be problems."

Oppitzhauser described as "catastrophic" the decision - so far unexplained by the company - to leave Roiss at the top for months after his departure was announced. "(OMV) has lost all credibility," he said.

Three sources close to the situation say OMV could cut jobs but a Nov. 24 board meeting in Abu Dhabi - home base for sovereign wealth fund IPIC, OMV's second-biggest investor after the Austrian state - yielded no news.

"Everyone is exhausted and trying to survive until the Christmas holidays. That's the reality," one source close to OMV said. "I don't think that in the short term there will be big changes" to its gas business and its focus on exploration.

Chairman Kemler, who also heads state holding company OIAG, is departing after Finance Minister Hans Joerg Schelling described developments at OMV as "unprofessional".

One source close to the situation said the new CEO may well be a politically connected Austrian rather than a foreign energy expert, typical of a country where top jobs often go to people close to one of the governing parties.

(Additional reporting by Stanley Carvalho in Abu Dhabi; editing by David Stamp)

By Alexandra Schwarz-Goerlich and Shadia Nasralla