The Nasdaq 100 index is up an incredible 41.6% through Sept. 1 and has been a huge long-term winner. You can own a stake in it via the Invesco QQQ Trust (QQQ 1.54%). In this video, Motley Fool contributor Jason Hall explains what happened the last two times it was up so much so fast, and explains what investors should be focusing on now. 

*Stock prices used were from the morning of Sept. 19, 2023. The video was published on Sept. 19, 2023.