What could keep you in a 150% surge like gold miners Jan-August?

That's right, multiple timescale fractal analysis on wave trend oscillators. In this case, the bottom row 8-day oscillator for GDX gave a crossover buy signal in mid-September 2015 that didn't roll over as overbought sell until August 2016 for a gain > 100%. Oscillators on all timescales shorter than 8 days embedded with hundreds of premature sell signals to choose from!