Shares of wearables maker Fitbit opened up more than 20 percent on Monday.
The move up comes four days after the company, which is valued at $4.1 billion, opened 52 percent above its IPO price at $30.40.
Fitbit had priced its initial public offering at $20 a share on Wednesday.
Nevertheless, while the company's stock has been performing well since going public, it is is competing in an increasingly crowded market, with rivals like Apple, Garmin, and Jawbone competing for a piece of the lucrative space.
Fitbit CEO James Park told CNBC's "Squawk on the Street" ahead of the IPO on Thursday that he believes his company can stay competitive even as Apple and other electronics makers ramp up marketing for all-purpose wearables like the Apple Watch.
"There's over $200 billion of consumer spending on health and fitness. This is a massive market. There's room for more than one dominant player," he said. "The brand Fitbit is really synonymous with health and fitness tracking, so we feel that we have really significant competitive differentiators in the market."
—CNBC's Tom DiChristopher contributed to this report.