The plot was left out of the public record apparently because it was discovered in part from intelligence gathered through surveillance authorized by the Foreign Intelligence Surveillance Court (FISA) in Washington, DC. Though there are ways to use such evidence at trial, the Justice Department tries to instead attempt to secure convictions on more typical varieties of crimes like fraud and money-laundering. That was the path chosen in case of the NYSE bomb plot that never was.
The stock exchange, at 11 Wall Street, is just a half-mile away from the site of the World Trade Center towers that were destroyed during the Sept. 11, 2001 terror attacks by al Qaeda. Nicknamed the "Big Board," the exchange is the world's largest stock market with the total value of the companies it lists hovering at more than $16.6 trillion.
Though an attack on the building would be a colossal symbolic blow to the country, the market itself would remain largely intact because the vast majority of trading is now done online, and the market's computer network was relocated to off-site locations in the wake of the 2001 attacks.