Transatlantic Holdings

$6B in net premiums, ranking third among the top 10 by net premium volume. Acquired by Alleghany Corporation in 2012 for $3.4B, then folded into Berkshire Hathaway with the 2022 Alleghany acquisition. Operates as a specialty reinsurer across casualty, property, and specialty lines in 35+ countries, with a 20% lower expense ratio than the industry average.