Don't expect a real hard selloff; this is an alternating wave coming off the June Swoon deep selloff, but could still have some pretty fierce selling and ^^Vix.
Index will likely go on to form double top and new All-Time High, breaking up from channel later this year after resting comfortably at ~24840-25040 for a few days.
We are in a 'reactionary wave' meaning countertrend, corrective; the Primary trend is Bull, and this looks like a primary 4th down wave in 5 wave bullish impulse.
This fourth wave (Y/D on chart) will possibly consist of a full 5 wave corrective impulse, we will see more as it unfolds, which will help gauge depth of pulloff.
Fifth wave will possibly have extraordinary strength and breadth, as it is a combo of several coincident bullish impulses (V)(5)(v)(E) of multiple waves cycles converging.
In short; it could be a trip to the Moon. Don't miss the launch!
Notice how rising support lines reach back to intersection at "Y" corrective wave- look for strong support around former resistance at 25040.
If wave breaks thru S1 @.382 Fibo, it will likely find firm S2 around 0.50 Fibo @24840. I wouldn't bet on a deeper pullback, although a flash crash is always possible.
Comments are always welcome-
Good luck!