As an aside to the parent poster, an often-stated guideline for the maximum amount you should own in the companies you work for is 10% of your portfolio value [1][2]. Modern portfolio theory (Markowitz, et. al.) calculations for a bundle of assets probably would bear out that 20% in a single stock is not on the efficient frontier [3].
[1] https://www.marketwatch.com/story/dont-invest-in-your-compan...
[2] https://www.forbes.com/sites/maggiemcgrath/2013/10/22/how-mu...
[3] https://en.wikipedia.org/wiki/Efficient_frontier