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.

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.

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