QQQ - Nasdaq has reached it's first

Price reached the Warning Line 1.

This is a natural support, because it's a standard deviation stretch. From here, price has a high tendency of mean-reversion.

How far?
Most of the time it shoots back to the Lower-Medianline-Parallel.

Beware of the potential resistnace zone.
This level is a good one to take partial profits.

As for a stop, I would put it below the last swing-long. I may play it with Options (for example a Risk-Reversal), giving me more leeway to the downside if it's not playing out immediately.