So, although the jury is still out there on which of the two larger patterns is evolving, we now know the market did five waves (grey, minute-i,ii, iii ,iv,v) up off the October 3 TVC:SPX 2855.94 low, completing (green) minor-3/c. The 3 is for the impulse, the c label is for the diagonal. So the Bulls want to see the green "alt: 4" complete at ideally TVC:SPX 3042: the 100% retrace as in a standard impulse pattern wave-3 often reaches the 161.80% Fib-extension of wave-1, measured from wave-2 , and then wave-4 should drop down to the 100% Fib-extension before wave-5 does (ideally) a nice 5=1 extension to the 200% Fib-extension. The latter is in this case at TVC:SPX 3229. So, last night the market reached TVC:SPX 3158, which is exactly the 1.618x extension and started today's decline. A BINGO for the standard impulse pattern so far. This patterns is exemplified by the orange arrows. Ultimately, price will need to move and close below last week's low at TVC:SPX 3091, to confirm wave-3/c has completed, but the look weak, is negative, and sentiment readings have been frothy for weeks, so all suggest this should be accomplished over the next few days.
The alternate is that we thus only saw three (green) minor waves up and that completed (red) intermediate wave-c of the diagonal, and wave-d is now underway. Note, I label the diagonal in letters to distinguish it from the impulse. Price will have to move and close below TVC:SPX 3040 and especially below 3022 to tell us the diagonal pattern is in play. Thus there's still some ways to go... If that happens, then the current decline will be labeled as red wave-d and it should drop to ideally TVC:SPX 3005+/-15. Now that still means there will be at a minimum a wave-e to complete (black) major wave-3 at around TVC:SPX 3200, followed by another wave-4 and 5 (grey arrows).
Thus, the current decline is one way or another still a great buying opportunity, and we'll just have to monitor the price action carefully to better determine when and where this musical dance of chairs ends.