* Rhoen eyes removing 90 pct acceptance threshold -source
* Decision seen in late 2012, early 2013 -source
* Rhoen names Martin Siebert as new CEO (Recasts with source)
FRANKFURT, Nov 7 (Reuters) - Rhoen-Klinikum is looking into changing its bylaws to remove a major hurdle to any takeover by a rival after a bid by Fresenius failed earlier this year, a company source said.
The move would involve changing a rule that requires shareholders representing at least 90 percent of Rhoen's stock to approve any major strategic changes.
"That is one of the options to be looked at by a working group of the management and supervisory boards," the person told Reuters on Wednesday after Rhoen named a new chief executive.
Rhoen declined to comment.
Rhoen's founder and Chairman Eugen Muench introduced the unusually high acceptance threshold to protect the company from hostile bids but ironically it proved insurmountable after he initiated the merger deal with Fresenius earlier this year.
Since a change to the bylaws would also require a 90 percent approval rate, such a move could still fail if there was resistance from major shareholders.
When Fresenius tried to buy Rhoen, for instance, rival hospital operator Asklepios bought shares in Rhoen to prevent Fresenius from reaching the 90 percent shareholding in Rhoen that it needed.
A decision on whether to seek a change to the bylaws is to be made late this year or early next year, the source said.
Rhoen earlier also said it named executive board member Martin Siebert as its new CEO, a day after cutting its 2012 profit outlook due to the cost of restructuring one of its hospitals.
The position became available when current CEO Wolfgang Pfoehler said he would step down at the end of the year after he was effectively sidelined by Rhoen's chairman in a takeover bid by Fresenius that ultimately failed.