Archipelago Holdings, based in Chicago, operates the Archipelago Exchange, an all-electronic stock exchange.

Archipelago Holdings, the owner of ArcaEx, the largest electronic stock market, confirmed late last night that it would buy the Pacific Exchange for about $50 million.

Archipelago Holdings, 11 million shares.

From 2002 to 2004, he served on the Board of Manager of Archipelago Holdings.

The deal also values Mr. Putnam's quarter of Archipelago Holdings at roughly $25 million.

Archipelago Holdings, owner of the nation's first electronic stock trading network open to the public, raised $126.5 million in an initial offering after cutting the share price.

That deal closed Tuesday and shares of NYX, previously Archipelago Holdings, started trading yesterday at $67.

In 2004, the exchange earned $24.6 million and Archipelago Holdings posted $68.9 million in profit.

He added that the company had an investment in General Atlantic Partners, which owns a piece of Archipelago Holdings, the parent of ArcaEx.

In January, Archipelago Holding, owner of ArcaEx, spent $50 million to buy the Pacific Exchange.