Illumina, Inc. (ILMN)

Illumina makes machines that read DNA — nearly all the world's genome sequencing runs on its instruments.

The instrument-and-consumable model: a sequencer sits in a laboratory for years while reagents and flow cells are bought for every run. Consumables supply most of the revenue at high margins, so what matters is not machine sales but how much research is run on the installed base.

The company spent several years dealing with the consequences of buying a blood-based cancer test developer: regulators on both continents blocked the deal and forced it to be unwound. Growth now runs into the budgets of research institutions and biotech start-ups, and into competitors arriving with platforms of their own. The company pays no dividend.