There are only a handful of effective ETFs focused exclusively on biotechnology. Nevertheless the sector contains companies that will probably produce more effective medical treatment and healthcare than all the insurance plans and HMOs combined. This is the next big thing for the human race as in the future immunization and cures for disease will allow people to live longer and healthier lives. As an anecdote a very famous and successful heart surgeon told me a few decades ago that his profession would no doubt be obsolete someday due to advances in biotechnology.
Biotechnology companies are valued more for their future promise than current earnings and sales. This has always been the case making PEs sometimes very high and confusing more uninformed investors. At the same time when there are clinical trial failures of new drugs or treatments the related company's shares may plunge significantly. Naturally successful results can lead to dramatic stock gains. One other little known trait is that when earnings from more conventional sectors struggle, investors often turn to the biotech sector seeking better performance away from earnings. It may seem an odd pattern, but it is something I've noticed over more than a few decades.