Mega wave 2 would be the Mega A-B-C from the dotcom bubble, to the crash, to the great recession. Since then a wave 3 started, which has not yet ended.
Most recent december's crash (year ago) would be wave 4 of the mega wave 3 according to this count.
Fibonacci as suport and resistance levels.
The long targets are sofar arbitrary, as predicting a new ATH is very tricky on long time frames.