I may be able to add value by reflecting on recent events and what is my current read here. The 50 line proved to be a good exit signaled in 2015 June/July after clear divergence between the upward price action and strength declining on this graph. The indicator also suggest that extreme caution should be exercised the pattern very much resembles the 2007 January - 2008 September window. Having said that I do not think all should reach to the panic button as 2010 and 2011 also showed similar patterns and while it was painful it did not end up in a full blown recession, probably because the big drivers like policy makers learnt how to smooth out these sharp declines.
I do think that the overall macro indicators (trends and not the recent data published) are concerning, however I do not think they warrant a GFC. There is a lot of speculative play around oil pricing which is a key driver here combined with a lot of leading sovereign nation troubles. There is increased risk indicated by spreads and credit default swap basis points but its nowhere close to the risk we had with the unsecured house loans back then. I also think that the continuous bull run for the past few years was overextended and the correction is/was due. What Im unsure of is whether this level is consolidation before resuming uptrend or there is a further 20% drop before riskier assets can start to appreciate.
Whatever your risk level is I suggest taking small (2 to 30% depending and no leverage) long positions only at these levels or just stay in cash until there is more clarity, this is clearly a highly volatile window.
In any market one can do trades on the shorter time frame even intraday with higher risk, this graph is about longer term investments.