Here is what I am talking about as it relates to SPY. These charts are correlations plotted with SP500 price.
DIX The DIX is simply the aggregated dark pool indicators of the S&P 500 Index. It is, therefore, a measure of market sentiment from the point of view of dark liquidity—a largely unexplored source of information. For the sake of utility, the DIX uses dollar-weighted trading volume to compute the ratio of dark pool buying to dark pool selling.
GEX Users will also note that we display, in tandem with the DIX, the gamma exposure (gex) of the S&P 500. Conventionally, our GEX metric is measured in shares-per-1%-move, but for the sake of consistency, the index GEX is also measured in dollars (per 1% move of index components).
When GEX is a high number, it acts as a brake on market price. When GEX is low (including negative), it acts as an accelerator. Practically, the "brake" stifles the market's upside while the "accelerator" ultimately enables upward price action resembling a squeeze (in both form and function).