MRKMerck & Company, Inc. Common Stock (new)

Merck is a drug maker whose revenue is heavily concentrated in the oncology medicine Keytruda.

Keytruda is an immuno-oncology medicine used across a wide range of tumours, and it accounts for a very large share of company sales. That concentration is both a strength and a vulnerability: while the patent holds, the drug earns exceptional margins, but the expiry date is known in advance and priced into the stock.

Beyond oncology the company is strong in vaccines, including the human papillomavirus vaccine, and in animal health, which produces steady income with little exposure to human drug regulators. Subcutaneous formulations of the flagship medicine are in development and could extend its commercial life.

The strategy of recent years is dealmaking: acquiring companies with late-stage assets to prepare a replacement early. Risks are typical for the industry — trial outcomes, regulatory decisions, price pressure from government programmes. Merck pays a dividend.