US specialty insurance company RLI has acquired Rockbridge Underwriting Agency, which is a general agency specializing in medical malpractice insurance.

RLI chairman & CEO Jonathan Michael said the deal will enable the company to tap market opportunities with the help of Rockbridge's specialized underwriting expertise and discipline.

The acquirer expects that the transaction will add nearly $20m of premium to its business on an annual basis.

Commenting on the deal, Rockbridge founder & chairman James Brooks said, "With RLI's resources and support, we are confident we can offer even better service to our customers."

Houston-based Rockbridge Underwriting Agency provides insurance for individual physicians and physician groups in all 50 US states through a network of retail and wholesale brokers.

RLI offers a diversified portfolio of property and casualty coverages and surety bonds across the US and manages subsidiaries including RLI Insurance, Mt Hawley Insurance, RLI Indemnity and Contractors Bonding and Insurance.