The logo of the pharmaceutical company Stada Arzneimittel AG is pictured at its headquarters in Bad Vilbel near Frankfurt March 14, 2012. REUTERS/Alex Domanski

(Reuters) - German generic drugmaker Stada STAGn.DE has received a 3.6 billion euro ($3.83 billion) takeover offer from private equity group Cinven, the Financial Times reported.

Cinven’s offer follows a year-long activist campaign to improve Stada’s profitability by Active Ownership Capital, one of its largest shareholders, and is believed to be pitched at close to 58 euros a share, the Financial Times reported, citing sources.

Cinven declined to comment. Stada was not immediately available to comment.

Advent, Bain Capital, CVC and Permira are all assessing the bidding war closely and could make a bid, the FT sources said.

In August last year, Stada’s CEO Matthias Wiedenfels promised a more modern, dynamic approach to running the company, saying it had to improve its transparency, flexibility, hierarchies and communication, although it had no need to change its strategy.

AOC put forward four candidates for Stada's supervisory board for election at the AGM, including former Novartis NOVN.S manager Eric Cornut for chairman, and said it also supported two of the four candidates proposed by Stada.

Another activist investor, Guy Wyser-Pratte, who has a stake of just under 3 percent, said in July that buyout firm CVC Capital Partners was interested in buying the drugmaker and that would be a better plan than AOC’s suggested board overhaul.