Possible Clues:

• Where E*Trade is traded: Abbr.
• Ticker locale: Abbr.
• A bell ringer closes it: Abbr.
• The Big Board, initially
• Org. whose first ticker was installed in 1867
• Big Board, briefly
• Org. eyed by e-traders
• The Big Apple's Big Board, briefly
• Big Board: Abbr.
• Org. with a National Historic Landmark building in lower Manhattan