Scor SE slumped the most in more than a decade in Paris trading after rival Covea abandoned efforts to buy the French reinsurer, ending one of the country’s most acrimonious takeover attempts in recent years.

Covea said that a transaction with Scor, in which it owns an 8.2 percent stake, is no longer among its “strategic options” after the company declined to enter talks about a friendly deal, according to an emailed statement Tuesday. Covea had previously reiterated its interest even after Scor’s board spurned an 8.3 billion-euro ($9.5 billion) unsolicited offer last year.

An acquisition of Scor would have helped Covea almost double its premium income and diversify its business beyond home, auto, life and health insurance coverage. Insurers and reinsurers have become popular acquisition targets for strategic as well as private equity buyers searching for higher returns. Scor, whose shares were among the best performers among European insurers last year, slumped as much as 15 percent in Paris trading, the most since 2008.

Scor “learned with great surprise and astonishment” that Covea issued its statement during market hours, the reinsurer said. The company, which closed 11 percent lower in Paris, said it’s suing Covea and some of its banks.

Covea cited “continued attacks and hostile tactics” which it had been subject to since its Aug. 24 offer — adding that these had intensified in recent days — and Scor’s refusal to engage in talks for its decision to abandon the offer. Scor denied it was using “hostile tactics.”

Yet shortly after Covea’s announcement, Scor said it is starting criminal action against the company and its chief executive, Thierry Derez, over the preparation and submission of last year’s offer. Scor has started actions before the Paris criminal court against Derez for breach of trust, and against Covea for concealment of breach of trust. Derez was forced to resign from Scor’s board in November following “multiple reminders” by the reinsurer of a conflict of interests situation.

Covea said in a statement after the market closed that it “strongly denies” all Scor’s allegations.

Scor is also taking civil action against Rothschild & Co. in France and against Barclays Plc before the High Court of Justice in London “for serious breach of confidence and trade secrets.” Spokesmen at Barclays and Rothschild declined to comment.

The insurance industry has been consolidating amid pressure on margins and as some private equity companies seek ways to tap the large pools of premiums that need to be invested.

Axa SA, the largest French insurer, last year agreed to purchase XL Group Ltd. for $15.3 billion, the biggest-ever European acquisition of a U.S. insurer. Apollo Global Management LLC has increased its stake in reinsurer Catalina Holdings Bermuda Ltd. amid a broader insurance push, and Carlyle Group LP has been expanding its team to do more deals in the sector.