The company that makes GoPro cameras is filing for a confidential IPO. 

A confidential IPO allows a company to keep its financial information private until weeks before its stock starts trading. To qualify for a confidential IPO, a company needs to be generating less than a billion in annual sales.

Last year, GoPro founder Nick Woodman said the company did $521 million in gross sales for 2012, and Forbes predicted it would double that in 2013. We don't know what happened, but the secret IPO suggests GoPro didn't double sales.

GoPro cameras are small and durable. They are often used for action sports to provide a first-person demonstration of what it's like to jump off a mountain or ride a snowboard, for instance. They're also used for other video production when a small, unobtrusive camera would be helpful.

Woodman started his company when he and his friends were frustrated they couldn't capture good video of themselves surfing. He started by just doing camera straps but eventually made GoPro cameras.

A camera sells for $300 a pop, and Woodman is selling millions of them every year.

Here's the release on the IPO:

SAN MATEO, Calif., Feb. 7, 2014 /PRNewswire/ -- GoPro, Inc. announced today that it plans to conduct a registered initial public offering of its common stock. The offering is expected to commence after the SEC completes the review process initiated by GoPro's confidential submission on Friday February 7, 2014 of its draft registration statement.

This announcement is being made pursuant to and in accordance with Rule 135 under the Securities Act of 1933. As required by Rule 135, this press release does not constitute an offer to sell or the solicitation of an offer to buy securities, and shall not constitute an offer, solicitation or sale in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of that jurisdiction.

This article originally appeared on Business Insider.

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