In Chrome DevTools, I can't find any HTML file when inspecting the network tab on investopedia.com.
How to find the HTML file?
There is not alway an HTML file. For example with investopedia.com, the HTML content is obtained from the https://www.investopedia.com URL, but there is no HTML file.
With the Chrome DevTool you can filter by resource type. If you click on "Doc", you will see only requests returning HTML content.