Biotech IPOs are booming, but is the frenzy almost over?

Biotechnology companies have been going public at a blistering pace this year, even as private investors are pouring more and more money into younger and younger startups.

Through Friday, there were 38 new listings by biotech companies this year, raising almost $3.9 billion, the most since a wave of upstart drugmakers went public in 2000, stirred by excitement over an early generation of genetic therapies.