<p>This is a guest post by Karl Loomes, a market analyst at Astec Analytics, part of SunGard. The views expressed are those of the author.</p><p>When looking at securities lending data and short selling activity in a stock I am always cautious when I see a rise in a company's share price matched by an influx of short sellers.Obviously some are betting the move is overbought or artificial, not to mention the potential for the short interest itself to put pressure on prices.</p><p>Looking at Research In Motion (RIMM) over the past month or so, I am feeling such caution. Data from SunGard's Astec Analytics has been showing this exact trend; as RIM's stock price has managed to climb around 40% since the start of November, both the number of its shares being borrowed, and the price traders are paying for the privilege of borrowing them (both proxies for short selling), have climbed in turn borrowing volume climbing 70% while the cost rose to its highest value in over five years. Indexed this trend is even clearer.</p><p>Chart: Astec Analytics (click to enlarge)</p><p><a href="http://www.forbes.com/sites/steveschaefer/2012/12/04/short-selling-are-bets-on-blackberry-10-leaving-rim-ripe-for-a-slide-or-a-squeeze/">Keep reading...</a></p>