NEW YORK—Warren Buffett’s Berkshire Hathaway Inc. on Monday struck an agreement to buy insurance company Alleghany Corp. for $11.6 billion, only weeks after the 91-year-old billionaire bemoaned a lack of good investment opportunities.
Alleghany, the owner of reinsurer Transatlantic Holdings Inc., would expand Berkshire’s large portfolio of insurers, which includes auto insurer Geico, reinsurer General Re, and a unit that insures against major catastrophes and unusual risks.
