What Is a Patent Cliff?; Fool.com via Fox Business, 7/6/16

Motley Fool Staff, Fool.com via Fox Business; What Is a Patent Cliff? :

"When a company is issued a patent, it can sell the item covered by the patent on the open market without having to worry about competitors coming in and snatching up a piece of the action. But the problem with patents is that they only have a limited life, and when they run out, they can significantly impact a company's bottom line. This is a particular problem in the pharmaceutical industry, where drug companies rely on patents to sell the products they work so hard to develop. That's why drug companies are often subjected to what's known as a patent cliff.

A patent cliff is what happens when a company's revenue starts plunging, or falling off a cliff, because an established product's patent reaches its expiration date and competitors can then start selling that product. While the term technically applies to any industry, it most frequently comes into play when talking about pharmaceutical companies."