The relaxation of a 31-year-old regulation on disclosing interest rate-related losses could potentially net US insurers hundreds of millions of dollars.

After lobbying, regulators in Seattle changed how insurers acknowledge these losses, allowing them to use the cash for new policies, business investments, or share price enhancements.

As of December, 23% of Fitch-rated life insurers have negative interest rate maintenance reserves, increasing from 8% last year.

The National Association of Insurance Commissioners draft plan allows insurers to collect some losses over time. Long-term bond investors will benefit most from the revisions.