The IPO Buzz: Acelyrin (SLRN) Prices Upsized IPO at $18 – High End

Upsized is the word of the week. Acelyrin Inc. (SLRN) upsized its IPO again at pricing – selling 30.0 million shares – up from 26.5 million shares, the upsized amount in the recently amended prospectus – and priced the IPO at $18.00 – the top of its range – to raise $540.0 million on Thursday night (May 4, 2023). That double dip into the upsized zone gives Acelyrin the distinction of being the largest IPO for a biotech startup since 2021, according to BioPharma Dive.

Acelyrin’s IPO follows hot on the heels of the successful NYSE debut on Thursday (May 4, 2023) of J&J’s spinoff of Kenvue (KVUE). The $3.8 billion Kenvue IPO is the largest IPO since EV company Rivian went public in November 2021.

Acelyrin’s stock is expected to start trading today (Friday, May 5, 2023) on the NASDAQ.

After the closing bell on Wednesday, Acelyrin’s IPO was upsized to 26.5 million shares from its initial size of 20.6 million shares in an S-1/A filing. The disclosure came quickly after the IPO’s books closed at 4 p.m. EDT that day (Wednesday, May 3, 2023).

Morgan Stanley, Jefferies, TD Cowen and Piper Sandler were the joint book-runners of Acelyrin’s IPO.

This is a much bigger biotech IPO than the typical biotech deal of 10 million to 12 million shares. (See Structure Therapeutics (GPCR) and Mineralys (MLYS) for comparison.) The inflammatory disease biotech’s IPO was said to be “well covered” at launch early Monday. The talk was that big sector funds were in for the deal. The IPO’s initial terms were disclosed shortly after sunrise on Monday (May 1, 2023).

Acelyrin, based in Agoura Hills, California, is a late-stage clinical biopharma company targeting inflammatory diseases with its drug development pipeline. Its leading product candidate, izokibep, a small protein therapeutic, is in Phase 2b/3 clinical trials to treat patients with hidradenitis suppurativa (HS), an inflammatory skin disease that causes painful small lumps under the skin, usually in the armpits, the groin, the thighs or other areas of close skin-on-skin contact; psoriatic arthritis (PsA)  and uveitis (an inflammatory eye disease). The company was founded in 2020.

**Note Principal shareholders include AyurMaya Capital Management Fund L.P., Westlake BioPartners Fund II L.P., Opaleye L.P., entities affiliated with OrbiMed and Citadel Multi-Strategy Equities Master Fund Ltd., according to the prospectus.

Worth reading: Acelyrin raised about $500 million in private fundraising rounds in less than 12 months through last September, according to Fierce Biotech.

Like many biotechs, Acelyrin has no revenue and a history of net losses. For the last 12 months, Acelyrin reported a net loss of $64.8 million on no revenue, according to the prospectus.

(For more information about this company, please check the IPO Calendar and the individual IPO Profiles found on’s website.)

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Disclosure: Nobody on the staff has a position in any stocks mentioned above, nor do they trade or invest in IPOs. The staff does not issue advice, recommendations or opinions.

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