(Bloomberg) -- Zenas BioPharma is seeking to raise $150 million or more in a US initial public offering, people familiar with the situation said, as biotechnology companies return to the market for first-time share sales.

The Waltham, Massachusetts-based clinical-stage biopharmaceutical company may begin marketing the offering to prospective investors as soon as July, the people said, asking not to be identified as the information is private.

Deliberations are ongoing and details of the offering such as timing and size may change, the people said. Representatives of Zenas didn’t respond to requests for comment by phone and email.

Biotechnology IPOs on US exchanges have raised $1.6 billion so far this year, more than double the $447 million raised for the same period last year, according to data compiled by Bloomberg.

The post-listing performance of this year’s biotech crop has varied widely, with shares in six of this year’s nine deals having fallen below their respective offer prices, the data shows. CG Oncology Inc., the best performing among them since its debut in January, has climbed more than 60% over its IPO price.

Zenas develops and commercializes therapies in inflammation and immunology. In May it announced the closing of an upsized $200 million series C preferred stock financing, led by biotech venture fund SR One along with New Enterprise Associates Inc., Norwest Venture Partners and Delos Capital. Zenas raised $118 million in a series B fundraising in 2022, an earlier statement showed. 

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