More than the telephone, however, the New York Stock Exchange gained its preeminence because it aggressively used its ticker tape to disseminate price information.
The maker of Scotch-brand tape was sued by a competitor who accused 3M (nyse: MMM - news - people ) of using price rebates to break into the market for private-label tape.
When you read the tape you can determine whether a stock will go up or down from its present price by looking strictly at the bids, the offers, and the prints.