NEW YORK — Shares of gene therapy developer Bluebird Bio Inc. surged in their trading debut.

Its shares climbed $9.91, or 58.3 percent, to close at $26.91 Wednesday after trading as high as $27 earlier in the session.

The company's initial public offering of 5.94 million shares had been priced Tuesday at $17 per share, above its initial expectations of $14 to $16 per share.

That raised $101 million before underwriting costs and other expenses.

Bluebird is developing gene therapies for severe genetic and very rare diseases.

The underwriters of the IPO have the option to buy another 891,000 shares of the Cambridge, Mass., company over the next month.