BillionToOne (BLLN) said Wednesday it priced its upsized initial public offering of almost 4.6 million class A shares at $60 each, for about $273.1 million in expected gross proceeds.

Underwriters have a 30-day option to purchase up to 682,665 additional shares, the company said.

The shares are expected to begin trading Thursday on the Nasdaq Global Select Market under BLLN, with the offering slated to close Friday, subject to customary conditions, it said.