The price of a seat on the New York Stock Exchange (search) tumbled to its lowest level since 1996, the exchange said on Friday, which comes as the Big Board grapples with a shift to electronic trading and possible regulatory changes that could significantly alter its trading dominance.

The NYSE said that a seat sold for $1.15 million, down $100,000 from the previous sale on Aug. 17 and more than 50 percent below its 1999 peak of $2.6 million.

Seat prices began their sharp decline after the Big Board revealed last year that former chairman Richard Grasso (search) had received a $188 million compensation package, which ultimately led to his forced resignation.

Prices leveled off after the appointment of current chief executive officer John Thain (search). But the recent unveiling of a new NYSE plan that modifies the NYSE's open auction system of stock trading by upgrading its electronic trading capabilities -- and reduces the role of its elite floor traders -- is contributing to uncertainty that is undermining seat prices.

In addition, the Securities and Exchange Commission (search) is considering changes to securities laws that could empower the Big Board's competitors, and divert business away from the exchange.