The QQQ is now very heavily weighted to a handful of NASDAQ stocks, especially Apple, and could be quite risky in a bear market:
"the relative performance of this handful of names has been rather pronounced this year. In fact, the five largest weightings in the index, the "Fast Five" — Apple, Alphabet, Microsoft, Amazon, and Facebook — have increased an average of 22 percent this year, and they now comprise nearly 42 percent of the entire Nasdaq-100!