Diagnostics Company BillionToOne Valued At $5.8 Billion In Public Offering

BillionToOne’s shares soared on its first day of trading, giving the company a market cap of $5.8 billion.

Oguzhan Atay, a Turkish immigrant with a Ph.D. in systems biology from Stanford University, started BillionToOne in 2016 with the idea of creating noninvasive prenatal genetic tests for common diseases, like sickle cell anemia and cystic fibrosis. Today, the Menlo Park, California-based company went public on the Nasdaq stock exchange, raising $273 million, in an offering that was upsized to meet investor demand. By the end of trading, its shares were up more than 80%, at $109 from the offering price of $60, giving it a market cap of $5.8 billion.

That makes BilliontoOne the rare medical diagnostics company to have a successful IPO this year, even more unusual given the federal government shutdown.

But BillionToOne, which started with prenatal blood tests and expanded to cancer testing, has built a significant, fast-growing business. It booked $209 million in latest 12-month revenue (through June 30) from 508,000 genetic tests, according to its offering document. That compares with last year’s revenue of $153 million, itself up 19-fold from $8 million in 2021. While the company is losing money, those losses have been shrinking, to just $4 million in the first half of 2025.

At a price of $109 a share, Atay’s stake in the business (including shares and vested options) would be worth $335 million. His cofounder, David Tsao, the company’s chief technology officer, holds a roughly similar stake, worth nearly $325 million.

“We have blown past every projection we had at the time,” Atay, the company’s cofounder and CEO, told Forbes. “We are not trying to change the market or convince Congress to change reimbursement. We are taking risk on the technical [side], to do something that is not just 5% better.”

Its patented technology can detect a single DNA letter of a single DNA molecule out of a total of 3 billion in a human genome (thus the company’s name)—helping it determine if a developing baby was at risk of serious disease from one maternal blood sample. Blood tests are far less invasive than traditional tests like amniocentesis in which doctors draw amniotic fluid to test for genetic disorders.

Atay, 37, and Tsao, 36, started with two common genetic blood disorders: sickle cell and beta-thalassemia. In 2023, they expanded into cancer testing, beginning with tests for people who already have cancer. BillionToOne is continuing to work on new diagnostic products in oncology, including those that could be used in early detection of cancer, one of the holy grails of testing.

Still, diagnostics is a hard and capital-intensive area, and big testing companies like $27 billion (market cap) Natera have been around for decades. “In the beginning it was very difficult,” Atay said, noting that BillionToOne was not only unknown to doctors, but was also out-of-network for insurers. “We were outspent and outnumbered in every region we were in,” he said. To acquire customers during the Covid-19 pandemic, he scheduled meetings with physicians in their parking lots, bringing masks that he had special-ordered from overseas with him. Today, BillionToOne is in-network with 70% of insurers, Atay said.

“He’s humble, but he’s a beast,” said Shahram Seyedin-Noor, managing partner of Civilization Ventures, a healthcare-focused investment firm that was one of BillionToOne’s first investors.

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BillionToOne raised its first $15 million in March 2019. It has since raised nearly $375 million from investors that include Norwest and Baillie Gifford. The company did not need the capital from today’s public offering, but chose to go public to bring on institutional investors, Atay said.

Today, BillionToOne projects in its offering document that the market for its existing genetic tests is worth more than $20 billion, while its pipeline of products in development could increase that to $100 billion. While prenatal tests are a big deal, early detection of cancer could be even larger. “That’s where a lot of the excitement for our company lies,” Atay said.

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