Short sellers managed to find opportunities in the North American markets in 2013 despite the most heavily shorted companies outperforming the S&P 500 index, according to Markit Securities Finance.

The past 12 months have been tough for short sellers as the US markets saw record highs.

“While many have noted that it’s been a terrible year for short sellers, with the most heavily shorted companies actually outperforming the S&P 500 index, there have been stocks where short sellers have called it correctly,” said a spokesperson for Markit.

The 20 best performing shorts fell by over 41% after seeing short interest reach a new annual high.

“Volatile” pharmaceutical companies dominated the top short list. Ariad Pharmaceuticals, which researches, develops and commercializes the small molecule medicens for cancer treatment, led the way as the worst perforing share.

Over the year short interest in the company reached 13 new weekly highs. According to Markit, the best timed short sellers took positions in late August, prior to a 76% decrease in the share price.

Vical Inc had the highest average share price underperformance, falling by 63% on average after 12 new annual highs in demand to borrow. The firm develops gene-based cancer treatments and infectious disease vaccines by using DNA technology.

Gold presented an opportunity for short sellers as the price of the commodity fell by 25%. Gold exploration and development company Allied Nevada Gold suffered disappointing earnings and its shares are down 88% year to date. However, Markit said that short sellers were late to tap up this opportunity as demand to borrow the firm’s shares did not reach an annual high until April.

Short sellers benefitted from taking positions in Kirkland Lake Gold whose share price fell 59%.

The most successful short of the year was Orbite Aluminae which saw an 84% drop in share price following increased demand to borrow in January.

J C Penny has been a popular short for several years but short interest dropped to a low of 11% in the summer which then jumped above 25% before another big price decline. Short sellers targeted Angie's List after its initial public offering in 2011 but it has not been a good short trade until the latter half of this year.