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February 19, 2021

Guilford’s Quantum-Si to go public in $1.46B merger

Jonathan Rothberg

Another startup founded by Guilford bioscience entrepreneur Jonathan Rothberg is going public through a merger with a “blank check” company.

Quantum-Si, which describes itself as a pioneer in next-generation semiconductor-chip based proteomics, announced it is merging with HighCape Capital Acquisition Corp. in a deal that values the company at $1.46 billion.

The deal is expected to close during the second quarter of this year, pending shareholder approval. The combined company will trade on the Nasdaq under the symbol “QSI.”

HighCape Capital Acquisition Corp. is a special purpose acquisition company, or SPAC, sponsored by HighCape Capital LP, a New York health-care focused investment firm founded by Connecticut serial entrepreneur and venture capitalist Kevin Rakin.

SPACs are shell companies formed specifically to raise capital through an initial public offering to acquire an existing company. 

They have become a popular way for startups to go public without going through the regulatory hurdles of an IPO. They are known as "blank check" companies because investors are not told what company is being acquired at the time of the offering.

Rakin, who is also a co-founder of New Haven biotechs Cybrexa and Athena Therapeutics, said in a statement that Quantum-Si’s business strategy aligned well with his company’s investment philosophy.

“We have confidence that this highly passionate and experienced management team is well-positioned to deliver on its bold vision of revolutionizing the proteomics market,” he said. “We look forward to supporting Quantum-Si and building a sustainable business that will be a disruptive force in the proteomics industry for the years to come.”

Quantum-Si will net around $514 million in the deal, including up to $115 million from the SPAC and another $425 million from an oversubscribed private investment in public equity (PIPE).

Investors participating in the PIPE include Foresite Capital Management, Eldridge, accounts advised by ARK Invest, Glenview Capital Management LLC and Redmile Group LLC.

Rothberg, who founded Quantum-Si in 2013, will become executive chairman of the publicly traded company and continue to hold a controlling interest. Current Quantum-Si shareholders are expected to own roughly 61%.

Quantum-Si says it has developed a next-generation protein sequencing platform that is on track to launch commercially in 2022 for research use. 

Rothberg, who is best known for inventing inexpensive, next-generation high-speed DNA sequencing, said Quantum-Si seeks to do the same for sequencing proteins, which can potentially lead to new ways to diagnose disease. 

“DNA sequencing changed medicine and research by revealing what could happen in the body; protein sequencing shows what is happening right now,” Rothberg said in a statement. 

Quantum-Si will be the second Rothberg company to go public via a SPAC merger. His pocket-sized ultrasound startup Butterfly Network began trading on the NYSE this week after merging with Longview Acquisition Corp.

Contact Natalie Missakian at

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