** Bain Capital-backed medical technology firm Heartflow's HTFL.O shares jump as much as 65.8% in their Nasdaq debut
** Stock opens at $28 vs $19 IPO price, valuing the firm at nearly $2.3 billion
** HTFL late Thursday sold 16.7 million shares above the marketed range of $17- $18 apiece for gross proceeds of $316.7 million in an upsized IPO
** Mountain View, California-based HTFL upsized its offering and raised the proposed range earlier this week, reflecting strong demand
** HTFL marks the third sizable medtech listing in New York in less than a month
** Founded in 2007 as Cardiovascular Simulation, Heartflow's AI-enabled products help physicians diagnose and treat heart disease
** J.P. Morgan, Morgan Stanley and Piper Sandler were the lead underwriters for the offering