Inspire Medical Systems enjoyed a big debut Thursday on Wall Street, with its shares jumping 56 percent from its initial public offering price of $16, closing at $24.98.

The rise capped a robust offering for the Maple Grove-based maker of implantable electric stimulators to treat sleep apnea. The company’s offering was larger than previously announced at 6.75 million shares, up from 5 million, and priced at the top of their range, raising $108 million.

The total value of the IPO could rise to as much as $124 million if underwriters eventually exercise their purchase options on another 1 million shares, according to a filing with the Securities and Exchange Commission.

Either way, Inspire Medical’s IPO weighs in as the second-largest initial offering of stock for a Minnesota company in the past year, behind Ceridian HCM Holding’s $462 million raised in April.

Inspire Medical makes an implantable medical device that treats stubborn obstructive sleep apnea, or OSA. The National Institutes of Health said as many as 12 million Americans have OSA, a condition that can lead to high blood pressure, heart disease, excessive daytime sleepiness and mood disorders.

The mainline medical treatment for OSA is typically to wear a continuous positive airway pressure (CPAP) mask at night, but many users don’t find success with that system. Inspire’s system, implanted under the skin, uses a pacemaker-like device to monitor a person’s breathing and administer mild electrical stimulation to the hypoglossal nerve, which controls the movement of the tongue and other muscles important to keeping a person’s upper airway open.

The Inspire system first won U.S. Food and Drug Administration approval in 2014, based on technology and intellectual property spun out of Medtronic in 2007. Inspire Medical founder and CEO Tim Herbert spent 11 years at Medtronic before launching the sleep-apnea company, which has about 120 employees.

The company reported a $17.5 million loss for 2017 on revenue of $28.6 million; that compares with an $18.5 million loss on revenue of $16.4 million the previous year.

In addition to Ceridian and Inspire Medical, Minnesota’s run of IPOs in the past year have included Bridgewater Bancshares, which raised $58 million in March; Celcuity LLC, $26 million last September; Calyxt Inc., $56 million last July; and ASV Holdings Inc., $26.6 million in May 2017.

 

joe.carlson@startribune.com 612-673-4779