The name and the claim sound like someone's idea of a joke: the Wunsch Auction System, looming threat to the New York Stock Exchange. The setting is no more promising. Ex-broker Steven Wunsch, 44, is launching his enterprise from an apartment crammed with stationery, two sagging sofas and a personal computer. But Wall Street and the 199-year-old N.Y.S.E. regard Wunsch with utter seriousness. His mission is to prove you can exchange stock without stock exchanges, and he seems to be succeeding.
The Wunsch Auction System opened for trading last week, linking buyers and sellers of all registered stocks directly through a...