Data Stream Gym for Reinforcement Learning – Stock Market, TimeSeries Data

Other public (near) real-time data streams include London TfL Traffic Data: https://tfl.gov.uk/info-for/open-data-users/

And many others listed here: https://stackoverflow.com/questions/22535217/whats-are-some-...

Although I love the idea of the Data Stream Gym I just wonder how useful RL can be for the stock market given the efficient market hypothesis (and the fact that are already HFTs acting in that space using all available data).