Down close to 50% so far this year, Twitter Inc. (NYSE:TWTR) stock is getting plenty of interest from short-sellers. Will they continue to be rewarded? Fool contributor Tim Beyers isn't so sure. .

In the following video, he reveals two metrics that speak to how well the underlying business is performing. First, he says that first-quarter ad revenue growth at 125% year over year exceeded that of overall revenue growth, which came in at 119%. That's an important indicator, in that it proves Twitter is drawing users to its ad platform despite initial limitations and intensifying competition.

Second, mobile ads accounted for 80% of advertising revenue. That's a remarkable stat, and well ahead of Facebook (NASDAQ:FB), which gets 59% of its revenue from mobile ads. In each case, Tim says Twitter is executing in the areas that are most important to its future as a business.

Mobile is a particularly big opportunity. According to eMarketer, the mobile ad market is on track to grow more than 75% this year, and only two companies -- Facebook and Twitter -- are expected to grow their share of the spending.

Now it's your turn to weigh in. Do you believe the sell-off in Twitter stock is warranted? Do you believe its mobile strategy will pay off for investors? Please watch the video to get the full story, and then leave a comment to let us know your take, including whether you would buy, sell, or short Twitter stock at current prices.

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Tim Beyers is a member of the Motley Fool Rule Breakers stock-picking team and the Motley Fool Supernova Odyssey I mission. He didn't own shares in any of the companies mentioned in this article at the time of publication. Check out Tim's Web home and portfolio holdings, or connect with him on Google+Tumblr, or Twitter, where he goes by @milehighfool. You can also get his insights delivered directly to your RSS reader.

The Motley Fool recommends BMW, Facebook, Nike, and Twitter and owns shares of Facebook and Nike. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.