Any Arbitrage or arbitrage like egy Relies on NON-Linear Price/Return- Relations, between the Basis Investment and its Instrument. So in the event that you start looking for Arbitrage chances, you need to look for Relations. Deterministic (better) or stochastic (not so good) Relations. For spread stakes non-linearity is loed in r/(1 r), and it is deterministic. Comparable to Gamma in Options, the convexity at Bond Prices or the pricing of the Dollar Index. Not so explicit and likely not deterministic is the connection between all and SP and VIX. As a data mining job you can regress all data against all information by employing a quadratic (or greater) fitting model, trusting for significant and STABLE Parameters.