24/7 Wall St.

Short sellers are an interesting lot in the investing community. It may seem un-American to bet on stocks or the market going down. That being said, there are many reasons that shares can be sold short, and they do not have to be bets against the company. Still, sometimes there are companies where short sellers get very aggressive, to the point that you might think they have it in for the companies.

24/7 Wall St. has tracked some key actively traded stocks in which the short interest rose massively over the second half of March. These companies also have large percentages of the float held short, and most of them have a high days-to-cover ratio (the short interest versus an average daily volume). Many smaller companies have seen their short interest rise even higher, but companies that have micro-caps or that are thin volume are much more specific stories.

Here are seven stocks with short interest that has screamed higher in the final weeks of March 2017.

Aurinia Pharmaceuticals Inc. (NASDAQ: AUPH) may have been unknown to many investors until recently, but the short sellers know it well now. Aurinia was just featured in our look at stocks under $10 that are up 100% to 300% already in 2017, with the surge here on moving its lupus drug study ahead to Phase 3 trial. Aurinia’s short interest rose to 7,751,369 shares by the March 31 settlement date, up 82.5% from the 4,248,045 shares short in mid-March. This is now 15% of the float, and due to the active trading, it is still only about one day to cover.

Avis Budget Group Inc. (NASDAQ: CAR) must still be feeling the competitive threats from Uber and others to the point that short sellers think the core business could face secular threats. Its March 31 short interest of 21,612,348 was up over 21% from the 17,764,920 shares short in mid-March. That is a gain of 21.7%, and it represents 25.9% of Avis Budget’s entire float. This stock remains more than 30% lower than its 52-week high.

FireEye Inc. (NASDAQ: FEYE) has been in the news of late with turnaround hopes, but the data security company still loses money despite high demand. FireEye’s short interest of 33,942,651 shares at the end of March was up almost 21% from the 28,106,414 shares two weeks earlier, and that represented 21.5% of the float. Trading at about $12.15 now, FireEye has a 52-week high up at $18.73, and this was briefly a $70 stock back in 2014.

Hostess Brands Inc. (NASDAQ: TWNK) has had its share of woes over the years, and if one food is a “sin food” it would have to be Twinkies. The short interest for Hostess rose by 41.6% to 7,900,320 at the end of March from 5,578,656 shares in mid-March. This represents 9% of the float and was six days to cover.

Rent-A-Center Inc. (NASDAQ: RCII) was last seen at $10.55, still down about one-third from its 52-week high of $15.94. Its short interest was 23,823,168 shares at the end of March, up about 21.5% from the previously reported 19,616,306 shares. What should really stand out here is that this is a whopping 46.2% of Rent-A-Center’s entire float, and it would take 14 days to cover all short positions.

Synergy Pharmaceuticals Inc. (NASDAQ: SGYP) saw its short interest scream higher by 32.3% as of the March 31 settlement date from just two weeks earlier. Its short interest was 62,126,396 shares, up from an already high 46,975,492 shares short in mid-March. This represents almost 29% of the entire float and eight days to cover. Trading at $4.50, Synergy has a 52-week range is $2.62 to $7.15.

Windstream Holdings Inc. (NASDAQ: WIN) saw its short interest rise a whopping 37.2% as of the most recent settlement date to 29,370,277 shares. Its mid-March short interest was 21,411,688. The number of Windstream shares short was 16% of the entire float, and it represented six days to cover. Another short seller attack on high-yielding dividend telecom and communications shares continues, and Windstream’s share price of $5.66 compares with a 52-week range of $5.16 to $10.46.