An overlay between Dow30, SP500 and Nasdaq100 reveals an interesting divergence between these major indices. The Dow30 made a reluctant new high today, the SP500 stayed flat and the Nasdaq100 plunged. It does not happen very often, but when it does, a correlation play is possible.
You can sell Dow30 and buy Nasdaq100, to later close both trades when these two indices correlate again. Other option in this case, is just shorting the highest indice of the correlation which made a reluctant new high.