Understanding market risk: What if I have all those Canadian oil stock purchased after August 31, 2020

I could not forget how wall street was tough, and gave three days in the row after Sept. 3, 4, and 7 bear market, corrections over 10% on SPX 500 index. 

So SU.TO still has 19.10% loss compared to August 31, 2020, IMO.TO -21.56%. 

Here is youtube.com link. 

Here is second link.