FRANKFURT (Reuters) - German industrial group Bilfinger (>> Bilfinger SE) installed corporate veteran Eckhard Cordes as chairman on Tuesday, hoping he can get the company back on track after a string of profit warnings that have hammered its shares.

The German's appointment is part of a reshuffle driven by top shareholder Cevian, a Swedish-based European activist investment firm. He inherits a company in turmoil whose top management members have all either left or are about to do so.

Chief Executive Roland Koch was booted out in August after issuing two profit warnings in a little over a month. Since then, the company has warned on profits two more times, most recently last week.

The German financial watchdog Bafin said on Tuesday that it was checking for possible insider trading in Bilfinger's shares following the profit warnings.

A former CEO at Germany's largest retailer Metro, Cordes has his work cut out for him.

Bilfinger has for years been transforming itself from a civil engineering and construction firm with low profit margins to a high-margin services group that designs, maintains or modernises industrial facilities such as oil rigs or wind energy parks as well as building them.

But the transformation of the Mannheim-based company has been complicated by the slow pace at which Bilfinger has integrated hundreds of small acquisitions it made over the years into its business, as well as by a crisis in Germany's energy sector, home to some of its biggest clients.

Some company insiders believe middle managers exaggerated the performance of their units to please Koch, a former politician in Chancellor Angela Merkel's Christian Democrat party who was once seen as a rival to the German leader.

"Uncertainty will remain high for the next three to six months. But after four profit warnings, expectations are rather low. The risk of a further fall in the share price... is quite limited, said Ingo Schmidt, an analyst at Hamburger Sparkasse.

Shares in Bilfinger, which have halved in value since April, gained after the Cordes announcement but eased back later and were up 0.9 percent at 45.90 euros by 15:55 GMT.

Cordes has the corporate experience that Koch lacked. The 63-year-old son of a leather salesman is an assertive, well-connected manager who pushed through a tough reorganisation at carmaker Daimler (>> Daimler AG).

He had less success however, in his subsequent posts at German family-owned investment company Haniel and later at Metro, one of Haniel's investments.

Cordes tried to sell or spin off Metro units including department-store chain Kaufhof and consumer-electronics unit Media-Saturn, but fell victim to a power struggle that hindered the restructuring and cost him his job in 2012.

More recently, as head of the powerful "Ost Ausschuss", a lobby group for German firms that do business in eastern Europe, he has urged caution in sanctioning Russia.

The hopes of Cevian now hang on Cordes, who as chairman of Bilfinger's supervisory board urgently needs to put a new executive team in place.

Cevian began buying shares in Bilfinger shortly after Koch was named CEO in 2011 and has since built up a 26 percent stake, the biggest share it holds in any firm, at a cost of roughly 800 million euros ($994 million), according to Reuters calculations.

The stake is now worth about 535 million euros.

Bilfinger takes Cevian, which has also stakes in European companies including British security firm G4S (>> G4S plc) and Swedish truckmaker Volvo (>> Volvo AB), into new territory.

"This investment is hard to compare with others Cevian has done," said a source familiar with Cevian's thinking, saying its typical analytical approach had failed to improve performance in this case, forcing it to act more radically. "This is probably the most activist approach they've ever taken," he said.

(Additional reporting by Matthias Inverardi and Maria Sheahan; Editing by Noah Barkin and David Stamp)

By Georgina Prodhan and Ilona Wissenbach