In this simulation of a mini-flash crash, Trader 1 is programmed to be bullish on prices, meaning she believes they're going to rise and initially buys more than she sells. Meanwhile, Trader 2 is bearish and sells more than he buys (represented by a positive number). Over time, Trader 1 becomes more bearish and Trader 2 becomes more bullish, until both get caught up in the bubble, driving up prices before the sudden crash around hour 6.