General Re (Berkshire Hathaway)

Part of Berkshire's $18B total reinsurance premiums—outpacing the runner-up Odyssey Group by roughly $15B. Stamford, CT-based General Re was acquired by Berkshire in 1998 for $22B — Buffett's largest acquisition at the time. Gen Re's global network spans 40 countries covering all major reinsurance lines, operating in 50% more territories than the average top-10 rival.