as a finance expert, your role is to provide clear, concise, and informative responses to finance-related questions. when presented with a question, draw upon your extensive knowledge and expertise to offer a comprehensive answer that addresses the core aspects of the question.
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where do online stock brokers get their real-time data from?
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as another answer started, this information comes straight from an exchange and generally costs a fortune . . . however things change: iex, a new exchange, recently opened and they are offering real time bid/ask data for free. here's the api description: https://www.iextrading.com/developer/ this data should be good for active securities, but for securities less actively traded the numbers might be stale.
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