(Bloomberg) -- Berkshire Hathaway Inc. agreed to buyMedical Liability MutualInsurance Co., extending Chairman Warren Buffett’s leadershipin the business of protecting doctors against lawsuits.

The target company is the largest underwriter of medicalprofessional liability insurance in New York and will convert froma policyholder-owned to a stock business, Omaha, Nebraska-basedBerkshire’sNational Indemnity unit said Monday in a statement that didn’tdisclose terms. Policyholder surplus, a measure of assets minusliabilities, was $1.8 billion as of Dec. 31, according to thestatement. The deal is expected to be completed in the thirdquarter of 2017, pending regulatory and customer approvals.

“MLMIC is a gem of a company that has protected New York’sphysicians, mid-level providers, hospitals and dentists like noother for over 40 years,” Buffett said in the statement. “Goodthings are worth waiting for.”

Insurance has long been a centerpiece of Berkshire, as theoperations generate premiums that Buffett can reinvest beforepaying claims. While the company counts more on giant subsidiarieslike auto insurer Geico and Gen Re, Buffett periodically addscompanies in niche markets.

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Berkshire in 2005 acquired Medical Protective Co., which has beenoperating for more than a century. That Fort Wayne, Indiana-basedbusiness reached a deal in 2011 to buy Princeton Insurance Co. fromMLMIC to expand in New Jersey. MLMIC policyholders will be entitledto a payout, based on the amount of premiums they paid, whenMonday’s deal is completed, according to a fact sheet on thecompany’s website.

The seller was advised by Keefe Bruyette & Woods and WillkieFarr & Gallagher LLP, according to the statement. Buffettdidn’t immediately return a message seeking comment.

Berkshire is the largest provider of medical professionalliability insurance in the U.S., according to data from theNational Association ofInsurance Commissioners. It competes with physician-led groupssuch as The Doctors Co. and other publicly traded insurers like CNAFinancial Corp. and American International Group Inc.

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