Experts Online : An Analysis of Trading Activity in a Public Internet Chat Room

We analyze the trading activity in an Internet chat room over a four-year period. The data set contains nearly 9,000 trades from 676 traders. We find these traders are more skilled than retail investors analyzed in other studies. 55% make profits after transaction costs, and they have statistically significant alphas of 0.17% per day after controlling for the Fama-French factors and momentum. Traders hold their winners 25% longer than their losers. 42% trade both long and short, with equal success rates, and almost double the profit per trade when short. The estimates show a strong influence from other traders, with a buy (sell) order 40.7% more likely to be of the same sign if there has been a recent post. Traders improve their skill over time, earning an extra $189 per month for each year of trading experience. They also gain expertise in trading particular stocks. Traders who raise their Herfindahl index by 0.1 raise their profitability by $46 per trade