Parabilis Sets $670M Biotech IPO Record After Decade of Building

Parabilis Medicines priced the largest venture-backed biotech IPO on record on Tuesday, raising gross proceeds of around $670 million at $20 a share on the Nasdaq Global Select Market. Shares closed their first day at $31.60, 58% above the IPO price, under the ticker PBLS. The Cambridge, Massachusetts company is the first to top the previous biotech record held by Kailera Therapeutics.

The price landed above Parabilis’ marketed range of $17 to $19 per share. PitchBook senior analyst Ben Zercher framed the deal as the moment a long-building company stepped into the public market, writing that the 2026 class of biotech IPOs is a backlog of strong companies that kept building through the funding downturn. Where Kailera went public within two years of incorporation, Parabilis took almost a decade.

The Record at $670 Million

Parabilis priced 33.5 million shares at $20 on Tuesday, above the $17-to-$19 range it had marketed, per the S-1. The $670 million in gross proceeds from the offering beat Kailera Therapeutics’ $625 million April raise, which had been the biotech record only weeks earlier. Regeneron Pharmaceuticals added roughly $75 million in a concurrent private placement at $18 a share, lifting the combined raise to nearly $745 million.

Trading under the ticker PBLS on the Nasdaq Global Select Market began Wednesday. Shares closed the first day at $31.60, 58% above the IPO price, lifting the company’s implied valuation to roughly $2.4 billion at the offering price, per Quartz’s reading of the filings. The five-firm underwriting syndicate was Leerink Partners, BofA Securities, Evercore ISI, Guggenheim Securities, and LifeSci Capital, per Parabilis’ S-1 registration statement filed with the SEC. The IPO is expected to close on or about June 11, 2026, subject to customary closing conditions.

Underwriters also hold a 30-day option to purchase an additional 5,025,000 shares at the IPO price, per the same filing. That option, if exercised in full, could add roughly $100 million to the total raised.

The Decade-Long Build Behind Parabilis

Founded as FogPharma in 2017, Parabilis raised six venture rounds before going public, per PitchBook. Its valuation fluctuated through a rebrand to Parabilis in 2024, leadership turnover, and the post-pandemic biotech winter that thinned private capital across the sector. Unlike Kailera, which was formed in 2024 and quickly stockpiled private capital before its April 2026 debut, Parabilis took a longer and far less linear road, Zercher wrote. The company has been built on technology developed by Harvard chemical biologist Gregory Verdine and commercialized through a peptide platform the company now calls Helicon, per the company’s account of the Helicon technology’s origins.

The company is led by Mathai Mammen, M.D., Ph.D., who serves as Chairman, CEO and President, per the S-1. By the time of the IPO filing, Parabilis had disclosed accumulated losses of $586.82 million and a first-quarter 2026 net loss of $45.316 million, with no reported revenue. To fund its operations, the company had raised a total $876.8 million as of March 31 across sales of convertible preferred stock, a term loan, and a Simple Agreement for Future Equity, per the S-1.

RA Capital’s Jake Simson, Ph.D., a partner in the firm, framed the case for the platform when the Series F closed: “With Helicons, Parabilis has established a platform with the potential to generate a robust pipeline of impactful therapies.” The contrast with Kailera is the point. Kailera went public in April 2026 less than two years after incorporation with a single obesity asset. Parabilis went public this month almost a decade after founding, with a platform and a lead candidate already in dose expansion.

Parabilis Stacked Two 2026 Deals

The IPO landed four months after Parabilis closed an oversubscribed $305 million Series F round on January 8, 2026. The round was co-led by RA Capital Management, Fidelity Management & Research Company, and Janus Henderson Investors, with participation from Frazier Life Sciences, Soleus Capital, and a long list of existing backers, per Parabilis’ announcement of the oversubscribed Series F round. The financing was completed at an increased valuation relative to the company’s prior round.

The Series F followed a Q4 2025 clinical update in which zolucatetide showed single-agent activity across five tumor types driven by Wnt/β-catenin alterations, including desmoid tumors, the indication that earned a Fast Track designation from the FDA in late 2025. The update also surfaced a strong scientific rationale for combination approaches in more biologically complex cancers, including microsatellite-stable colorectal cancer. The data were presented at the J.P. Morgan Healthcare Conference in January, where Parabilis said it would share additional desmoid, hepatocellular carcinoma, and familial adenomatous polyposis data.

In May 2026, Parabilis added a separate anchor: an up-to-$2.3 billion strategic research collaboration with Regeneron Pharmaceuticals to discover and develop a new class of therapeutics called antibody-Helicon conjugates. Regeneron agreed to purchase approximately $75 million of Parabilis common stock in a concurrent private placement at 90% of the IPO price, per the S-1. The combination of the Series F, the Fast Track and Orphan Drug designations, and the Regeneron deal gave Parabilis the demand to price above its marketed range. Parabilis said it plans to use IPO proceeds to fund a global registrational Phase 3 trial of zolucatetide in desmoid tumors, plus continued dose-expansion work in hepatocellular carcinoma and familial adenomatous polyposis.

Zolucatetide and the Helicon Platform

Zolucatetide, the company’s lead candidate, is an engineered peptide designed to directly inhibit the interaction between β-catenin and the T-cell factor family of transcription factors, a node inside the Wnt/β-catenin signaling pathway that no approved therapy addresses. The pathway is implicated in millions of cancer cases annually. Zolucatetide, formerly known as FOG-001, is the first and only direct inhibitor of the elusive β-catenin:TCF interaction, per the company. The drug has been evaluated in more than 150 patients across multiple solid tumor types to date, per the S-1.

The lead indication is desmoid tumors, rare noncancerous growths of connective tissue, where the FDA granted Fast Track designation in late 2025. In the dose-expansion cohort, researchers have seen tumor reductions in 100% of patients, with a 74% objective response rate in patients who have had at least two post-baseline scans, per the S-1. Parabilis also plans to study zolucatetide in hepatocellular carcinoma, the most common form of liver cancer, and in familial adenomatous polyposis, a rare genetic disorder that nearly guarantees colorectal cancer.

Our goal at Parabilis is to develop medicines with the potential to deliver truly life-changing impact for patients who urgently need new treatment options.

Mathai Mammen, M.D., Ph.D., Chairman, CEO and President of Parabilis Medicines, said the line in the company’s January 8, 2026 announcement of the Series F. The Helicon platform is the engine behind that mission. Helicons are α-helical peptides designed to bind protein surfaces that conventional small molecules and antibodies cannot reach, combining the precision of antibodies with the intracellular access of small molecules. The platform integrates AI- and physics-based computational modeling with high-throughput peptide synthesis, and has been built on a decade of work by Verdine and his collaborators. Beyond zolucatetide, Parabilis is advancing preclinical programs in prostate cancer, including degraders of ERG and an allosteric ARON, both historically intractable targets, per the company.

Twelve 2026 Biotech IPOs and Counting

Parabilis is the 12th biotech to list on U.S. public markets in 2026, per the S-1. The 11 biotechs that priced before it had already raised a combined $3.491 billion, compared with $1.556 billion raised by 11 companies at the same point in 2025. The backlog of late-stage private companies is the supply, and reopened investor appetite is the demand.

Kailera Therapeutics set the previous biotech record with a $625 million offering in April 2026, the only other biotech IPO to clear $600 million so far this year. Other recent offerings include Hemab Therapeutics’ $346 million raise and Odyssey Therapeutics’ $279 million debut, both upsized and closed in early May, per BioSpace. Six of the 11 pre-Parabilis IPOs are trading above their offering prices, led by Veradermics, a dermatology and aesthetics developer whose shares rose 520% from the IPO price to $105.32 a share by mid-May.

The class spans obesity, rare bleeding disorders, autoimmune disease, dermatology, and now Wnt-pathway oncology. Parabilis’ $670 million offering is the only deal of 2026 to top Kailera’s $625 million April mark.

Why This Window Is Different

PitchBook’s Zercher framed the 2026 IPO class as a backlog, not a bubble, writing that the rush of deals should not be dismissed as hype. The biotech IPO window is open again, and the 2026 class hitting the tape is a backlog of strong companies that kept building through the funding downturn, he said. The pandemic-era class of 2020 and 2021 went out with preclinical promises and a market that no longer valued them. The 2026 class is going out with Phase 1, Phase 2, and Phase 3 programs already in motion, and the trend is broader than biotech, with the broader 2026 IPO class opening up across sectors.

Parabilis’s clinical profile fits the pattern. Zolucatetide has been dosed in more than 150 patients, has shown tumor reductions in 100% of desmoid tumor patients in the dose-expansion cohort, and is heading into a registrational Phase 3 trial. The IPO will fund that trial and continued work in hepatocellular carcinoma and familial adenomatous polyposis. On offer at the IPO is a Phase 3-ready asset and a platform behind it, not a preclinical promise of the 2020 vintage.

• $670 million raised in the IPO from 33.5 million shares at $20 each
• 58% first-day pop, closing at $31.60
• $2.4 billion implied valuation at the offering price
• $305 million Series F closed January 8, 2026
• 150+ patients dosed with zolucatetide to date

Frequently Asked Questions

When did Parabilis Medicines start trading on Nasdaq?

Parabilis common stock began trading on the Nasdaq Global Select Market on June 10, 2026 under the ticker symbol PBLS. The shares closed their first day at $31.60, 58% above the $20 IPO price, per the company’s S-1.

How much did Parabilis raise in its IPO?

Parabilis priced 33.5 million shares at $20 each, raising about $670 million in gross proceeds. The company also gave underwriters a 30-day option to buy an additional 5,025,000 shares at the IPO price. A concurrent $75 million private placement from Regeneron Pharmaceuticals at 90% of the IPO price brought the combined raise to nearly $745 million.

What is zolucatetide designed to treat?

Zolucatetide, formerly known as FOG-001, is an engineered alpha-helical peptide designed to directly inhibit the interaction between beta-catenin and T-cell factor transcription factors, a node in the Wnt/beta-catenin signaling pathway that no approved therapy addresses. It is being studied in desmoid tumors, hepatocellular carcinoma, familial adenomatous polyposis, and other Wnt-pathway cancers, and has been dosed in more than 150 patients to date.

Who led Parabilis’s Series F round?

The $305 million Series F round, which closed on January 8, 2026, was co-led by RA Capital Management, Fidelity Management & Research Company, and Janus Henderson Investors. New participants included Frazier Life Sciences and Soleus Capital.

How does the 2026 biotech IPO window compare with 2025?

The 11 biotechs that priced before Parabilis in 2026 had raised a combined $3.491 billion, compared with $1.556 billion raised by 11 biotechs at the same point in 2025, per the company’s S-1. Parabilis’s $670 million offering is the largest of the year, followed by Kailera Therapeutics’ $625 million April debut.