Axis Capital Holdings and Bermuda-based PartnerRe have sweetened the terms of their merger proposal, in the latest bid to fend off hostile suitor Exor.

Axis has agreed a 52% rise in the dividend PartnerRe shareholders will get, pushing it up to $US17.50 ($23.74). This matches Exor’s offer for preferred shareholders.

“The merger creates opportunities neither company could really achieve on its own in the near term, including expense synergies in excess of $US200 million ($271.32 million), significant capital efficiencies and incremental growth opportunities,” Axis CEO Albert Benchimol said.

Axis and PartnerRe have moved their shareholder votes on the merger from this Friday to August 7.

The bidding war for PartnerRe began four months ago.

The dividend rise is seen as an attempt to win over investors who support Exor’s all-cash counter-offer of $US6.8 billion ($9.22 billion).

Italian-based Exor met investors in New York two weeks ago and improved its offer terms. It offered to lift the dividend rate on PartnerRe preferred shares by one percentage point and delay the call on three series of securities until 2021.

Last week Axis pledged to match Exor’s terms on preferred stock.

In January Axis and PartnerRe agreed an $US11 billion ($14.92 billion) merger to create one of the world’s largest reinsurers.

Exor holds about 10% of PartnerRe, making it the largest single shareholder.