18. Pfizer

Patent value: 29,329

Pfizer (PFE) was already at the top of the pharmaceutical industry when it paid $68 billion to take over rival Wyeth. The acquisition, completed in October 2009, makes it an even taller giant. With Wyeth's portfolio added, Pfizer has a peerless roster of patents and a pipeline that includes products for Alzheimer's disease, cancer, pain, mental health, diabetes, and inflammation.