The following is a list of the most shorted stocks in the S&P500 index, as measured by the short ratio. The ratio expresses the total number of shares shorted as a multiple of the average daily volume, i.e. the number of days needed to cover all short positions.

We're not going to go into detailed analysis for each company. The goal here is to give you a starting point for your own analysis.

Short float and performance data sourced from Finviz.

*(Click for expanded image)*

The list has been sorted by the short ratio.

* 1. Fastenal Co. (NASDAQ:FAST): *General Building Materials Industry. Market cap of $8.72B. Short float at 12.3%, which implies a short ratio of 16.43 days. The stock has gained 55.18% over the last year.

* 2. Sears Holdings Corporation (NASDAQ:SHLD):* Department Stores Industry. Market cap of $7.5B. Short float at 12.37%, which implies a short ratio of 16.25 days. The stock has lost -7.05% over the last year.

* 3. Cerner Corp. (NASDAQ:CERN)*: Healthcare Information Services Industry. Market cap of $7.55B. Short float at 13.55%, which implies a short ratio of 14.36 days. The stock has gained 20.63% over the last year.

*Property & Casualty Insurance Industry. Market cap of $5.13B. Short float at 10.22%, which implies a short ratio of 13.47 days. The stock has gained 29.61% over the last year.*

**4. Cincinnati Financial Corp. (NASDAQ:CINF)****:***Waste Management Industry. Market cap of $6.72B. Short float at 7.73%, which implies a short ratio of 13.3 days. The stock has gained 36.35% over the last year.*

**5. Stericycle, Inc. (NASDAQ:SRCL)****:***Staffing & Outsourcing Services Industry. Market cap of $4.44B. Short float at 10.55%, which implies a short ratio of 12.75 days. The stock has gained 20.13% over the last year.*

**6. Robert Half International Inc. (NYSE:RHI)****:***Asset Management Industry. Market cap of $2.67B. Short float at 13.94%, which implies a short ratio of 11.97 days. The stock has gained 10.85% over the last year.*

**7. Federated Investors, Inc. (NYSE:FII)****:***Publishing Industry. Market cap of $1.61B. Short float at 13.36%, which implies a short ratio of 11.78 days. The stock has gained 23.38% over the last year.*

**8. Meredith Corp. (NYSE:MDP)****:***Auto Dealerships Industry. Market cap of $3.92B. Short float at 11.03%, which implies a short ratio of 11.67 days. The stock has gained 45.93% over the last year.*

**9. AutoNation Inc. (NYSE:AN)****:***Waste Management Industry. Market cap of $17.07B. Short float at 7.44%, which implies a short ratio of 11.3 days. The stock has gained 11.67% over the last year.*

**10. Waste Management, Inc. (NYSE:WM)****:***REIT. Market cap of $5.94B. Short float at 10.22%, which implies a short ratio of 11.19 days. The stock has gained 8.03% over the last year.*

**11. Plum Creek Timber Co. Inc. (NYSE:PCL)****:***CATV Systems Industry. Market cap of $12.08B. Short float at 7.51%, which implies a short ratio of 11.18 days. The stock has gained 33.96% over the last year.*

**12. Discovery Communications, Inc. (NASDAQ:DISCA)****:***Drug Manufacturer. Market cap of $4.76B. Short float at 15.22%, which implies a short ratio of 10.9 days. The stock has gained 9.02% over the last year.*

**13. Cephalon Inc. (NASDAQ:CEPH)****:*** 14. Moody's Corp. (NYSE:MCO):* Credit Services Industry. Market cap of $6.4B. Short float at 11.02%, which implies a short ratio of 10.25 days. The stock has gained 10.52% over the last year.

*General Building Materials Industry. Market cap of $5.56B. Short float at 11.54%, which implies a short ratio of 9.77 days. The stock has lost -6.86% over the last year.*

**15. Vulcan Materials Company (NYSE:VMC)****:***Telecom Services. Market cap of $13.53B. Short float at 11.31%, which implies a short ratio of 9.39 days. The stock has gained 33.26% over the last year.*

**16. CenturyLink, Inc. (NYSE:CTL)****:***Electronics Stores Industry. Market cap of $3.37B. Short float at 23.86%, which implies a short ratio of 9.35 days. The stock has gained 5% over the last year.*

**17. GameStop Corp. (NYSE:GME)****:*** 18. Integrys Energy Group, Inc. (NYSE:TEG):* Gas Utilities Industry. Market cap of $3.82B. Short float at 8.33%, which implies a short ratio of 9.29 days. The stock has gained 24.94% over the last year.

* 19. Forest Laboratories Inc. (NYSE:FRX):* Drug Manufacturer. Market cap of $9.33B. Short float at 7.88%, which implies a short ratio of 9.09 days. The stock has gained 4.78% over the last year.

* 20. Legg Mason Inc. (NYSE:LM):* Asset Management Industry. Market cap of $5.38B. Short float at 10.13%, which implies a short ratio of 8.94 days. The stock has gained 30.24% over the last year.

**Disclosure: **I have no positions in any stocks mentioned, and no plans to initiate any positions within the next 72 hours.