Guess it depends if you look at percentages. The market looks like it lost about 20% after 2001. Decent drop
So
Dotcom crash
2008
Covid
Now
The current whatever-this-is doesn't even qualify as a full-blown recession yet. Too early to tell.
The dotcom bubble was a totally normal, run-of-the-mill recession.
So in terms of outstanding events, you really only have the Great Recession and covid. And when it comes to covid, the economic fallout was in large part driven by government overreaction. It was a huge crisis, but more because of the disruptions it caused to our everyday life than because of its economic impact.