Shares of Fitbit(FIT) - Get Report plunged by 12% on Friday, closing at $27.86. The San Francisco company sold fewer shares than it had anticipated in its secondary stock offering. 

In its filing with the Securities and Exchange Commission, Fitbit put three million shares of common stock up for sale. The company had initially proposed to sell seven million shares. Fitbit, which went public in June at $20 a share, announced on Nov. 3 that it would hold a secondary offering of its shares.

In its secondary offering, the shares were priced at $29 -- lower than Thursday's closing price of $31.68.

"Many of Fitbit's executives and venture-capital investors participated in the stock sale, which Sterne Agee CRT analyst Rob Cihra said gave the stock and the offering negative investor optics," The Wall Street Journalreported

"Fitbit's CEO and co-founder James Park sold 2.2 million shares," the Journal said. "Early investor Jonathan Callaghan of True Ventures sold 3.8 million shares. Another early investor, Foundry Group, sold 4.2 million shares. Even after these sales, all three investors and the other sellers still hold sizable stakes."

In a related development in the fitness-tracking industry, Texas-based Fossil Group(FOSL) - Get Report lost 37% of its value Friday, closing at $32.39. The company reported disappointing earnings results Thursday and also announced it would buy privately held Misfit, a smaller competitor to Fitbit.

Read TheStreet'sreport on Fossil's earnings miss on Thursday.

In addition, some analysts are expressing concerns about the Apple(AAPL) - Get Report Watch, which includes fitness trackers.

"Our view has always been that the Apple Watch is not going to destroy the traditional watch market," wrote Jefferies analyst Randal Konik. "Nevertheless, there are clear signs that wearable tech is gaining traction and changing the environment."

Apple shares declined by 2.9% Friday, closing at $112.34.

In his 40-plus years in the music business, which included a stint during the mid-1970s as a recording engineer on Bruce Springsteen'sBorn to Run album, Jimmy Iovine has certainly seen how quickly things can change in the fickle industry.

On Friday, Iovine's current employer, Apple, said it would shut down its Beats Music service at the end of the month. Apple bought Beats from Iovine and his business partner, Dr. Dre, for $3 billion just 18 months ago.

Subscribers to Beats will be able to move their content over to Apple Music, which Apple launched earlier this year.

If you are an Apple user click here to learn how to migrate your music from Beats to Apple Music on IOS. You can also go to the Apple Support page if you are an Android user.

Yahoo! (YHOO) shares dropped by 3.1% Friday, closing at $32.19, after SunTrust analyst Bob Peck wrote a letter to the company's board of directors, suggesting ways that CEO Marissa Mayer could improves its business.

Check out the full report by TheStreet's Technology Editor Chris Ciaccia to learn what Peck is recommending and to read his letter to the Yahoo! board.

Amazon(AMZN) - Get Report is giving Britain's supermarkets another run for their money by introducing a grocery service for Amazon Prime members, Bloomberg Newsreported. Amazon closed at $642.35 Friday, down 3.5%.

"Amazon Pantry, which debuted in the U.S. about 18 months ago, will be available across the U.K. starting today," the news service said. "The online site will offer more than 4,000 everyday essential items from beer to pet food.

"Amazon Pantry customers will be able to purchase a box of groceries weighing a maximum of 20 kilograms at a cost of 2.99 pounds ($4.55) for next-day delivery. If they exceed that limit in a single order, delivery of each additional box will be charged at a price of 99 pence."

Facebook(FB) - Get Report is testing disappearing messages as part of its Messenger app. The social media company said it is conducting a small pilot test in France.

Privately held Snapchat now lets users send a photo or video that disappears within 10 seconds.

Get more details about Facebook's new messaging test on SiliconBeat. Facebook shares closed at $103.88, down 3.8%.

And now, because it's Friday (and even if it wasn't), we are here to tell you that a Google self-driving car was pulled over for "driving too slowly" in Mountain View, Calif., where Google is headquartered.

Read this article on SiliconValley.com to find out what happened.

Shares of Google's parent company, Alphabet(GOOGL) - Get Report , closed Friday at $740.07, down 2.2%.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.