Although questions had arisen about how Box’s initial public offering would fare, public investors gave the company a warm welcome on Friday, its first day of trading.

Shares in Box, the online file storage company, opened at $20.20 on Friday morning, 44 percent higher than its I.P.O. price of $14 a share.

The stock continued to surge to close the day at $23.23, up nearly 66 percent, giving the company a market value of $2.7 billion. At that level, the start-up has surpassed the $2.4 billion valuation that it fetched in its most recent private financing round last summer. Its strong first-day performance may ease some concerns among investors that highflying Silicon Valley start-ups were looking overvalued.

Now that it has gone public, nearly a year after kicking off the process during a period of market upheaval, Box can focus on a more pressing issue: standing out in an industry that has quickly filled with competition, particularly from much bigger rivals like Google and Microsoft.

In a video presentation to investors, Aaron Levie, a Box co-founder and its chief executive, said that his company was at the forefront of “a once-in-a-generation shift” in storage. It is a message that has drawn clients like General Electric and the drug maker AstraZeneca.

Video

Though Box was one of the first and better-known online file storage providers, having been founded in 2005, larger competitors have moved in with offerings that are often significantly cheaper. The company has sought to differentiate itself by focusing on corporate clients and building products like collaboration tools for documents.

Box trades on the New York Stock Exchange under the ticker symbol “BOX.”