Shares of Ultragenyx fell after the company launched an underwritten offering of up to $300 million in shares.
The stock was down 12% at $32.35 in early trading. Shares have fallen 30% year-to-date.
The biopharmaceutical company said it has commenced the offering and is expected to grant underwriters an option to buy up to $45 million in additional shares.
Ultragenyx said the offering is subject to market conditions and that there can be no assurance as to whether or when the offering will be completed.