Long Term Models
The long term performance of equities and commodities both correlate with solar sunspot cycles, with secular bull markets ending around solar cycle peaks. The period from solar minimum to solar maximum is historically one of positive returns. Solar minima are associated with panics, crashes or bottoms.
Stock index seasonality correlates inversely with geomagnetic storm seasonality. Stock market returns are higher leading into and around new moons and lower into and around full moons. Inverting geomagnetism seasonality and combining with lunar phasing generates a stock market model.
S&P500 Stock Index versus R/J CRB Commodities Index
S&P500 Stock Index versus Daily Sunspots
Very interesting discussion on possible causes of the solar cycle. The links to papers in the comments are also good.
http://tallbloke.wordpress.com/2011/08/05/jackpot-jupiter-and-saturn-solar-cycle-link-confirmed/
Thanks Kerry. Norwegian Jan reckons there are 3 main cycles that regulate the sunspot-cycle and that a fourier spectrum reveals them: the ~10 year (half) synodic Jupiter-Saturn cycle, the ~11 year Venus-Earth-Jupiter, and the ~12 year Jupiter cycle.