FRANKFURT Activist investor Cevian's stake in German industrial services group Bilfinger (GBFG.DE) grew to 29.5 percent from 25.6 percent, a regulatory filing by Bilfinger showed on Friday.
That brings it close to the 30 percent threshold at which investors are forced under German law to make a full takeover offer.
Cevian, which has a policy of buying stakes in companies whose parts it sees as being more valuable than the whole, started buying shares in Bilfinger in 2011.
It instigated a management overhaul in 2015, after the group issued six profit warnings in a year, having run into difficulties in a shift from construction into services.
(Reporting by Maria Sheahan; Editing by Christoph Steitz)