Over betting markets as a whole, it's hard to distinguish 'manipulation' from simple 'overconfidence' by a certain side. The difference between InTrade and Bet

Over betting markets as a whole, it's hard to distinguish 'manipulation' from simple 'overconfidence' by a certain side. The difference between InTrade and Betfair over long periods is the large mystery... though given the lags/fees in getting money in, and the fact the markets aren't that large -- so maximum profits aren't very high -- seem likely to be part of the answer. There's a reasonable Robin-Hansonian-case to be made that attempts at prediction-market manipulation improve market accuracy over the long term, by increasing the rewards to those taking sides against the manipulator.