“While most people trading stocks at home imagine their orders zipping from their brokers onto one of the nation’s stock exchanges, almost none of the trades go anywhere near those public markets.

In reality, most trades placed through online brokers like TD Ameritrade and Scottrade are sold to Wall Street firms, which accumulate and trade against tens of millions of these shares a day, rather than send them to a regulated exchange like Nasdaq or the New York Stock Exchange. The Wall Street firms then quickly flip them and turn an easy profit because they have more resources and market knowledge than mom-and-pop investors…”

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