From Investorplace:
One of the most popular screeners for stocks to buy is looking at companies trading at 52-week lows. This is a common practice that echoes the well-known phrase of “buy low, sell high”. Ultimately, if investors can time buying stocks at their bottoms, there should be gains to follow. While that is not always the case, many large-cap stocks can be picked up on sale at 52-week lows due to a number of reasons, including weak earnings or guidance, or performance of peers.