(Reuters) -BillionToOne ( BLLN ) was valued at $4.4 billion on Thursday, after the molecular diagnostics firm's shares jumped 66.67% in their Nasdaq debut, becoming the latest company to tap U.S. bourses amid a government shutdown.

IPOs have made a striking comeback as AI exuberance and falling interest rates anchor equity markets to all-time highs, fueling investor confidence in new issuers after President Donald Trump's tariffs roiled global markets in April.

While a prolonged gridlock in Washington has curbed the Securities and Exchange Commission's abilities to review filings, the agency has eased listing restrictions to allow companies to tap public markets even as the shutdown continues.

The Menlo Park, California-based company's stock opened at $100 apiece, versus the $60 offer price.

It had sold 4.55 million shares above its marketed range of $49 to $55 apiece to raise $273 million in an upsized IPO on Wednesday, reflecting robust investor demand for high-growth biotech companies.

A slew of medical firms have gone public on U.S. exchanges this year. Peer Caris Life Sciences went public in New York in June, with shares trading more than 39% above issue price as of last close. BillionToOne ( BLLN ) is a molecular diagnostics company that develops non-invasive prenatal and oncology blood tests using its single-molecule sequencing technology. The company's revenue rose nearly 82% during the six months ended June 30 from a year earlier, with gross profit more than doubling over the same period. J.P. Morgan, Piper Sandler, Jefferies and William Blair were among the underwriters for the offering.