Alder BioPharmaceuticals of Bothell priced its initial public offering of stock at $10, below the expected range of $13 to $15.

Alder shares, listed on Nasdaq under the ticker ALDR, closed up 3 cents at $10.03 in their trading debut Thursday.

The offering raised $80 million before expenses for the biotech company, which is testing two drug candidates it developed — one to prevent migraines and one to treat rheumatoid arthritis and psoriatic arthritis.

Alder filed its IPO plans in mid-March, when biotech deals were booming. But investor enthusiasm for the sector has cooled, with the Nasdaq biotechnology index down more than 14 percent since March 18.

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