A membership seat on the New York Stock Exchange (search) rose to $2.4 million on Monday, up $600,000 from a sale last week and its highest since July 10, 2002.

Seat prices have increased since the exchange announced last week a plan to merge with electronic trading platform Archipelago Holdings (AX) and become a publicly traded company. Monday's seat sale was $300,000 less than the record price reached in August 1999.

The value of a seat on the Big Board has more than doubled since touching a low below $1 million in early January, driven by uncertainty surrounding the NYSE's business prospects.holders have found comfort in recent developments that affect the exchange.

The Securities and Exchange Commission (search) recently recommended changes to securities trading laws that will eventually favor automated trading platforms, and the Big Board is currently expanding its electronic trading capabilities.

But last week's surprise announcement that the NYSE was forming an alliance with Archipelago has largely underpinned the price of a seat. According to the terms of the deal, the NYSE's 1,366 seat holders will share a $400 million cash payout and divide among them 70 percent of the stock in a publicly-traded Big Board.