CHICAGO—CNA Financial Corp. said Tuesday that it has completed its deal with Berkshire Hathaway Inc. under which it will cede $1.6 billion in net asbestos and environmental pollution liabilities and pay a $2 billion premium to Berkshire for $4 billion in reinsurance coverage.

CNA said it expects to recognize an after-tax loss of about $370 million in the third quarter as a result of the deal.

Analysts have said the deal, which was announced in July, will remove a potentially major legacy liability for CNA.