Here come the billion-dollar biotech IPOs

June has been a banner month for biotech IPOs, with five listings amassing nearly $3 billion in cash. The next test: Are investors willing to support unicorn valuations?

This week, BridgeBio Pharma and Adaptive Biotechnologies are expected to price their long-awaited offerings. BridgeBio is seeking a roughly $1.7 billion valuation, and Adaptive is aiming for more than $2 billion.

So far this year, three companies have debuted at valuations north of $1 billion, but the returns have been mixed. Alector, working in neurodegenerative disease, is down about 5% since its IPO, and the NASH-focused NGM Biopharmaceuticals has fallen 14%. Gossamer Bio, which went public at a $1.1 billion valuation, has risen 39% in the months since.