* Bilfinger gets offers for Building and Facility segment
* Segment had been identified as one of two main pillars
* Sale would leave company exposed to energy sector (Adds comment from supervisory board source, updates shares)
By Georgina Prodhan and Ilona Wissenbach
FRANKFURT, Jan 14 (Reuters) - German engineering andservices company Bilfinger is considering selling itsmost profitable businesses, raising the prospect of investorsgetting a return from the struggling group but leaving itdependent on a volatile energy market.
Under new management installed by activist investor Cevian,Bilfinger issued a surprise midnight statement saying it hadhired advisers to review unsolicited offers of interest for itsbuilding, facility services and real estate divisions.
The company said it had not yet decided whether to sell thedivisions, which together have annual sales of about 2.4 billioneuros ($2.6 billion), or more than a third of the group's total.
A sale would leave Bilfinger, once a revered name in Germancivil engineering, with just its industrial plant servicingbusiness, which is highly exposed to the oil and gas market andhas been hit hard by low energy prices.
The 125-year-old company did not name the parties who hadexpressed interest in the divisions.
Its major competitors in the relevant fields are JohnsonControls, Strabag, Wisag, CBRE,Zueblin, Savills and Hans Huber.
"It surprised me completely. We're talking about a corebusiness. If it happens, one could truly call it the breakup ofa renowned company," said a supervisory board source who askednot to be named.
"It stands to reason that Cevian's wish for a return on itsinvestment in Bilfinger is one of the grounds."
UBS analysts, who rate Bilfinger "neutral", estimated thevalue of the businesses that may be sold at 1.66 billion eurosincluding debt.
Bilfinger's market capitalisation is 1.84 billion euros andit also has pension liabilities and debt of about 800 million.
DZ Bank analyst Thorsten Reigbar, who has a "buy" rating onBilfinger, wrote: "The news might raise hopes that Bilfinger'sindividual sum of the parts might have a higher value than thecurrent market cap."
But Bankhaus Lampe analyst Marc Gabriel pointed out thepotential pitfalls. "If it sells its only pearl, the only thingleft will be a non-growing industrial services business," hewrote in a note, reiterating his "sell" rating on the stock.
Bilfinger's shares traded 3.5 percent higher at 41.40 eurosby 1425 GMT, and were the second-biggest gainers in a 1.3percent-weaker German mid-cap index.
PROFIT WARNINGS
Bilfinger in its heyday built the Sydney Opera House and theMunich Olympic stadium, but it shed most of its constructionoperations in pursuit of higher-margin services businesses aftera strategy shift in the early 2000s.
The strategy turned sour, however, as many of Bilfinger'sservice contracts were with utilities and petrochemicalscustomers who cut back sharply on investments, hit by a switchto renewable energy and plunging oil prices.
Bilfinger warned on profits six times between the summers of2014 and 2015 as the situation deteriorated rapidly. Thatprompted 26-percent shareholder Cevian to install a newchairman, its second board member, and then a new chiefexecutive and finance chief.
Cevian, which has a policy of buying stakes in companieswhose parts it sees as being more valuable than the whole, hassunk more than 600 million euros into Bilfinger since it beganacquiring shares in 2011, according to Reuters calculations. Itsstake is currently worth about 471 million euros.
CEO Per Utnegaard, who took over last June, said in Octoberhe would build the group on the twin pillars of Industrial, theindustrial plant-services business, and Building and Facility.
"A decision on... a potential adjustment of the two-pillarstrategy which may be required thereby has not been taken,"Bilfinger said in its announcement on Wednesday night.
Utnegaard has already put Bilfinger's power plant servicingunit up for sale, a deal he hopes to conclude by mid-year.
Bilfinger is also in talks with German private equity groupTriton over the sale of its Water Technologies division, theremaining part of Building and Facility, for roughly 200 millioneuros, people familiar with that deal said.
Deutsche Bank is advising Bilfinger on the Power unit sale.Two people familiar with the matter said it was also the adviserreviewing the current bids.($1 = 0.9154 euros) (Additional reporting by Arno Schuetze; Editing by Keith Weir)