Researchers Ball and Brown (1968) identified a market anomaly commonly referred to as "Post-earnings-announcement price drift". Specifically, they observed that: Stock prices tend to slowly rise after companies report positive earnings per share. Stock prices tend to slowly fall after companies report negative earnings per share. Stock prices tend to slowly rise after companies report earnings that are higher than the average of published analysts' forecasts at the time. Stock prices tend to slowly fall after companies report earnings that are higher than the average of published analysts forecasts at the time