The Invesco QQQ ETF, which tracks the Nasdaq 100 index, has crashed this year and moved into a correction after falling by over 12.8% from its highest level this year. It plunged to a low of $471, its lowest level since September last year.

A stock market correction happens when a major index falls between 10% and 20% of recent highs, and that's exactly what has happened with the Nasdaq Composite, which is down over 9% year to date and over 13% from its Dec. 16 high (as of March 10).

It's been a challenging time for investors, as the Nasdaq Composite (NASDAQINDEX: ^IXIC) has plunged into correction territory -- falling by more than 13% over the past three weeks. Many Americans were already worried about the stock market leading up to this sudden dip.