It’s getting costlier for SPAC backers to buy insurance against future shareholder lawsuits, a fresh sign of soured sentiment toward these once-hot public offerings.

Insurance carriers that write policies to shield company directors and executives against shareholder lawsuits are increasing premiums for those affiliated with special purpose acquisition companies. Some insurers in this market—which  includes Axa XL, Chubb and Japan’s Sompo—are also becoming more selective in underwriting SPACs due to concern about a possible wave of litigation against SPAC sponsors and the companies they have taken public, say lawyers and brokers who work on the transactions.

Last summer, SPACs planning to raise $250 million in their initial public offerings would pay an average of $200,000 to receive $10 million of insurance coverage protecting their directors and executives, estimates Tyler McAllister, a senior vice president for insurance broker Marsh. Now those SPACs are paying $650,000 for half the amount of coverage, he said.

The jump in premiums is putting a strain on SPAC creators, who have to pay these costs out of pocket. The new lawsuits could pressure target companies to rein in their growth projections, which could lead to lower valuations on future SPAC mergers.