(Corrects third bullet point to read 'price' instead of 'prices')
* Pooling stakes with Oberbank expected to trigger share offer
* Mandatory offer of 20.81 euros/share planned in March or April
* Offer price below Monday's close of 24.60 euros
VIENNA, Jan 7 (Reuters) - Austrian investment group B&C Industrieholding GmbH has struck an agreement to pool its stake in aluminium group AMAG with that of Oberbank AG in a move that will likely trigger a mandatory offer of 20.81 euros per share for AMAG, B&C said.
AMAG shares closed the trading session at 24.60 euros.
B&C now has just under 30 percent of AMAG and Obergroup just over 5 percent, it said on Monday.
A holding above 30 percent requires a bid to be made to other shareholders under Austrian law.
B&C said its offer of 20.81 euros per share plus the 2012 dividend payout was above the legal minimum based on AMAG's trade-weighted share price over the past six months. It said the offer would probably start in March or April.
B&C and Oberbank executives said in a statement their goal was to strengthen their role as core shareholders in AMAG and support its growth.
"B&C Industrieholding does not plan a complete takeover or squeeze-out at AMAG," it said, adding AMAG would remain listed on the Vienna exchange and have a "significant" free float. (Reporting by Michael Shields; Editing by Greg Mahlich)