Seattle-based Sana Biotechnology priced its expanded initial public offering Wednesday evening, raising $575 million before expenses. The shares, offered at $25 and trading under the ticker symbol SANA, rose 40.4% to close Thursday at $35.10.

Renaissance Capital, which tracks IPOs, called it the biggest initial offering for a biotech in the preclinical stage, meaning it has no products in clinical trials. At the offering price, Sana’s market capitalization was $4.9 billion, according to Renaissance.

The company offered 23.5 million shares at $25 each, a significant increase from the originally contemplated offering of 15 million shares at $20-$23.

The 250-employee company, which also has operations in Cambridge, Mass., and South San Francisco, is working on “repairing and controlling genes (and) replacing missing or damaged cells” for a range of diseases.