A large specialty insurer has agreed to acquire a business that insures health plans against unexpectedly large losses.

HCC Insurance Holdings Inc., Houston, says it will pay $140 million in cash for the health products division of Allianz Life Insurance Company of North America, Minneapolis, a unit of Allianz A.G., Munich.

HCC hopes to complete the deal by Sept. 30.

The Allianz Life health products division sells stop-loss coverage to self-insured health plans.

The division also sells excess insurance for health maintenance organizations, provider excess for integrated delivery systems, and excess medical reinsurance for small and regional insurance carriers.

The division also runs Life Trac, a network for providing organ and bone marrow transplants.

The division generates about $300 million in gross premium revenue, HCC says.

Allianz Life President Douglas Reynolds says the company is selling the division to focus on core operations.

HCC Chairman Stephen Way says his company, also a large stop-loss provider, hopes to use the deal to improve stop-loss profit margins.

Completing the Allianz health products division would give HCC a total of about $750 million in annual stop-loss premium revenue, HCC estimates.