The oldest and most often repeated example of negative correlation is the relationship between stocks and bonds. For years, it has been believed that stocks generally do well when bonds do poorly, and vice versa. This belief took a real pounding in the mid-1990s, however. Just to prove that we are living in the real world, stocks and bonds both fell dramatically in 1994 and shot up in 1995. It is also important to look at the level of correlation among stocks in different companies.
Some economists see a negative correlation between restaurants and supermarkets.
When people have a lot of money to burn, the theory goes, they can afford to eat out and restaurant stocks do well. When money is tight, consumers economize by buying food from the store and eating in, so supermarket stocks do well. If these examples seem tenuous, it's because they are. When you're dealing with even one asset, it's difficult to guess future performance with any reliability. Guessing how two assets will perform in relation to each other is even harder.