Investment group Exor, which controls car maker Fiat Chrysler, said on Monday it had signed a deal to buy PartnerRe for $6.9-billion , ending a prolonged battle for the reinsurer against a rival bid from Axis Capital. Exor, the investment vehicle of Italy's Agnelli family, wants to branch out into financial services with its steadier and higher returns and limit its exposure to the more capital-intensive and cyclical automotive sector.