Exor has increased its offer for PartnerRe Ltd to about $6.8 billion, as it tries to derail the Bermuda reinsurer’s planned merger with Axis Capital Holdings Ltd.

Exor, the investment vehicle of Italy’s billionaire Agnelli family, now plans to pay $137.50 a share in cash for PartnerRe, a 5.8 per cent increase from the $130 per share bid that was rejected by the reinsurer’s board.

The Milan-listed firm also revealed that it has bought up about 9.3 per cent of PartnerRe’s shares at a cost of about $572 million, making Exor PartnerRe’s largest shareholder.

In an effort to secure the deal, Exor has offered PartnerRe a signed merger agreement that can be executed upon termination of the agreement with Axis. The Italian company has also filed proxy materials that allow investors to vote against the rival offer at an upcoming shareholders meeting.

Exor’s chairman and chief executive officer John Elkann made it clear this morning that the bid was a final offer.

““Our offer is superior,” Mr Elkann told Bloomberg News. “Going higher would be irresponsible for our shareholders. This is our final and last offer.”

Earlier this month, Axis, a Bermuda insurer and reinsurer, sweetened its “merger of equals” offer for PartnerRe with an $11.50 per share special dividend for PartnerRe shareholders. The revised offer came after Exor made its initial bid on April 14. An Axis-PartnerRe deal would leave PartnerRe shareholders owning about 51.5 per cent of the combined company.

Based on Axis’s May 1 closing share price of $52.33, the offer is worth between $125 and $126 per share.

PartnerRe’s board favoured the revised Axis bid, which would create the world’s fifth-largest property and casualty reinsurer. The companies have said their amalgamation would allow cost savings of around $200 million per year. This would likely include redundancies in Bermuda, where the two companies are based in neighbouring buildings on Hamilton’s waterfront.

In a statement, Exor’s Mr Elkann said: “Exor’s binding offer clearly delivers superior and certain value for PartnerRe shareholders, and provides a more attractive outcome for the company’s employees and clients.

“We hope the PartnerRe Board agrees and does the right thing. In any event, we believe PartnerRe shareholders deserve the opportunity to choose our offer and, in order to do so, we urge them to vote against the inferior Axis transaction.”

An industry analyst, Charles Sebaski, of BMO Capital Markets, said Exor’s revised offer “seems to be at a level that will be very hard for Axis to get close enough to keep Exor from winning”.

But if Exor does succeed in pushing Axis aside, there will be an added $280 million cost. That is the “break fee” built into the merger agreement, that must be paid by the company that opts out of the deal. The fee has been described as “excessive” by Exor.

Exor, which controls Fiat Chrysler and Italian football club Juventus, among its investments, has a market capitalisation of about $19 billion.

The Italian firm is set to boost to its cash reserves after it agreed on Monday to sell one of its holdings, commercial real estate firm Cushman & Wakefield Inc, for about $2 billion.