Warren Buffett is making moves.

Berkshire Hathaway said Monday morning it agreed to buy insurance company Alleghany for $11.6 billion, or $848.02 per share, in cash. The conglomerate said the deal “represents a multiple of 1.26 times Alleghany’s book value at December 31, 2021,” as well as a 16% premium to Alleghany’s average stock price in the past 30 days. The deal is expected to close in the fourth quarter of this year.

Alleghany shares rallied more than 15% in the premarket. Through its subsidiaries, Alleghany is involved in a number of different insurance businesses, including wholesale specialty, property and casualty, and reinsurance.

“Berkshire will be the perfect permanent home for Alleghany, a company that I have closely observed for 60 years,” Buffett, Berkshire’s chairman and CEO, said in a statement.

Alleghany CEO Joseph Brandon — who previously led Berkshire-owned General Re — hailed the deal as a “terrific transaction for Alleghany’s owners, businesses, customers, and employees,” noting that “the value of this transaction reflects the quality of our franchises and is the product of the hard work, persistence, and determination of the Alleghany team over decades.”

The deal may surprise some Berkshire shareholders, as Buffett and his right-hand man — vice chairman Charlie Munger — have expressed frustration in their search for a big acquisition. In his 2022 annual letter to shareholders, Buffett said he and Munger found little that “excites” them in terms of large acquisitions.

To be sure, $11.6 billion is a small number when compared with Berkshire’s massive cash hoard of $146.72 billion at the end of 2021.

“This is Berkshire’s largest full acquisition in a while, although the amount being spent ($11.6B) is relatively small and certainly doesn’t constitute the type of ‘elephant deal’ Buffett has repeatedly talked about,” Adam Crisafulli of Vital Knowledge said in a note.

Monday’s deal comes after Berkshire’s Class A shares hit a record high last week, closing above $500,000 for the first time.