Here's a couple of well known ones. Not sure if they were what you found:
https://en.wikipedia.org/wiki/Reminiscences_of_a_Stock_Opera...
https://en.wikipedia.org/wiki/Reminiscences_of_a_Stock_Opera...
So, considering a very simple formula could have been so effective, I wondered what they'd find at the library and if even that simple concept would have been available. What wouldn't be available is SEC data. But, as your second suggestion made clear, you could get the information for ratings agencies.