Short interest is a measure of how many shares have been sold short but have not yet been covered. An increase in short interest can indicate that investors are expecting the price of the stock to fall. In the case of AIG, the short interest has increased, which could indicate a bearish sentiment among investors. However, it's important to note that AIG's short interest as a percentage of float is still less than its peer group average, which could mitigate some of the potential downward pressure on the stock.