Private equity firm KKR (KKR.N) has acquired a stake of 14.1 percent in German research firm GFK (GFKG.DE), regulatory filings show, as it seeks to fight off rival investor Michael Dell.

Together with GFK Verein, KKR is seeking to acquire control over 75 percent of GFK by end of Feb. 10, but rival investor Michael Dell has also started building a stake.

Dell’s GFK shareholdings now amounts to 10.1 percent, the filings show.

KKR made its 43.50 euros a share GKK offer conditional on surpassing a 18.54 percent threshold.

Dell’s MSD Capital fund manages more than $12 billion in assets, the company says on its website, which lists merger arbitrage as one of its investment strategies.