Left chart: Combine leveraged ETF BIS (bear, bio x3) with XIV (or safer ZIV or SPLV) for a good deal on risk vs return. Right chart: BIS about to overtake EDZ (short emerging markets, x3 ETF).
Ratio: 1) currently 1.5 shares of BIS to every 1 share of XIV. This ratio changes over a period of days so must be monitored closely. 2) For less volatile combo's using ZIV or SPLV you will need (much) less BIS