Key events in the Transatlantic saga

JUNE 12—New York-based reinsurer Transatlantic Holdings Inc. and Zug, Switzerland-based specialty insurer Allied World Assurance Co. Holdings A.G. announce a stock-for-stock merger worth about $3.2 billion at that time.

JUNE 13—Tucson, Ariz.-based investment management firm Davis Selected Advisers L.P., which owns a nearly 24% stake in Transatlantic, says it has “serious concerns” about the Allied World deal.

JULY 13—Bermuda reinsurer and insurer Validus Holdings Ltd. offers a stock-and-cash deal for Transatlantic worth about $3.5 billion at the time. It also said it would add $500 million to Transatlantic's reserves, depending on results of its due diligence.

AUG. 7—Berkshire Hathaway Inc. reinsurance unit National Indemnity Co. offers $52 per share for Transatlantic, or around $3.25 billion at the time. Stock market turmoil diminishes the value of Allied World's offer to about $2.74 billion and Validus' offer to about $2.87 billion.

SEPT. 9—Advisory firm Institutional Shareholder Services Inc. recommends that Transatlantic investors vote against the Allied World merger.

SEPT. 16—The Transatlantic and Allied World merger collapses under investor pressure.

SEPT. 26—Transatlantic says it has entered into talks with an unnamed third party, reportedly involving an investor group that includes Joseph Brandon, former CEO of Berkshire Hathaway Inc.'s General Re Corp.

OCT. 11—Transatlantic says it has entered into deal talks with its fourth potential bidder, reportedly involving Hamilton, Bermuda-based Enstar Group Ltd. and New York-based C.V. Starr & Co.

NOV. 21—Transatlantic agrees to a stock-and-cash deal with New York investment holding company Alleghany Corp. valuing the reinsurer at roughly $3.4 billion. Transatlantic is to operate as a semiautonomous subsidiary of Alleghany, with Mr. Brandon serving as president of Alleghany Insurance Holdings L.L.C., executive vp of Alleghany and chairman of Transatlantic's board. Davis supports the deal.