ABBVAbbVie Inc.

AbbVie is a drug maker that has lived through the patent expiry of its flagship medicine and replaced it with a next generation.

For years the base was Humira, an autoimmune treatment and one of the best-selling drugs in the industry's history. Its patent expiry and the arrival of biosimilars tested the company's durability: revenue from that product declines, and the question was what would replace it.

The replacement is a next generation of medicines in the same field, plus neuroscience, oncology and aesthetics following the Allergan acquisition, including Botox. That diversification leaves the company less dependent on a single product than it historically was.

The industry model is unchanged: high margins under patent protection, a sharp fall once it ends, so value rests on the pipeline and on deals for external assets. AbbVie pays a dividend that is high by sector standards and is held for cash flow.