There’s an old saying that the stock market is the only place where, when prices are put on sale, the customers all run OUT of the store. When prices are marked down, and the VALUE of the merchandise is UNCHANGED (whether it’s socks or stocks), then it makes sense to buy. The key from the Brandes perspective is that the buyer must have a solid grasp of what that merchandise is worth. In our view, investors make a major mistake if they confuse price and value....and that’s especially easy to do when media coverage of markets tends to use “price” and “value” as interchangeable words.

Source: Berkshire Hathaway, Inc., 2008 Letter to Shareholders