Fitbit is tumbling

Fitbit reported second-quarter earnings results on Wednesday evening, and the company absolutely crushed expectations for sales and profits.

The maker of fitness trackers posted record quarterly revenues of $400.4 million, beating the forecast for $319 million according to Bloomberg. Adjusted earnings per share came in at $0.21, versus estimates for $0.08.

International sales surged 250% year-over-year in the quarter, and overall, 4.5 million devices were sold.

However, the 47% gross margin missed estimates for 48%.

Shares plunged as much as 10% in after-hours trading. The stock hit an all-time high during the session Wednesday and closed up 4% at $51.74.

The stock has rallied 74% since the IPO in June, when it opened 52% above its initial offering price.

In the earnings statement, CEO James Park said: "Our second quarter results included our highest quarterly revenue in the eight-year history of Fitbit. In the quarter, we introduced new features and services, expanded brand awareness, increased global distribution and further penetrated the corporate wellness market."

The company forecasts revenues of between $1.6 billion and $1.7 billion for the full year.

More to come ...

Shares were all over the place after the market close, falling as much as 9% after closing up 4% at $51.68. The stock is up 74% since the IPO in June, when it opened 52% above its initial offering price.