With the S&P 500 losing 16.8%, the Nasdaq 100 down 16.3% and the Dow Jones Industrial Average off 13.9% in October, all 10 of the best-performing exchange-traded funds in October were inverse funds. The top ETFs with their one-month total returns for last month were: PowerShares DB Crude Oil Double Short ETN ( DTO) at 66.6%, PowerShares DB Base Metals Double Short ETN ( BOM) with 53.5%, PowerShares DB Commodity Double Short ETN ( DEE) at 51.4%, ProShares UltraShort Real Estate ( SRS) with 50%, ProShares UltraShort Russell2000 Growth ( SKK) at 41.2%, ProShares UltraShort Russell MidCap Growth ( SDK) with 38.2%, Rydex Inverse 2x S&P MidCap 400 ETF ( RMS) at 37.4%, ProShares UltraShort Industrials ( SIJ) with 36.7%, ProShares UltraShort MidCap400 ( MZZ) at 36.5%, and Rydex Inverse 2x Russell 2000 ETF ( RRZ) with 36.4%. Five of the funds have been trading for at least a year, the minimum duration necessary to qualify for a rating by our risk-adjusted return ranking system. The ProShares UltraShort Real Estate ETF returned 33% over the past year, earning a C- rating. At 84.2% for the same period, the ProShares UltraShort MidCap400 ranked on the high side of average at C+. ProShares UltraShort Russell2000 Growth scored a rating of A, returning 92% for the year ending Oct. 31. This excellent performance was trumped by the 106.6% gain from ProShares UltraShort Industrials and 124.1% increase from ProShares UltraShort Russell MidCap Growth. Both of those ETFs topped out with A+ ratings. Source: TheStreet.com Ratings. Read this for an explanation of our ratings.