If we correct the error, we conclude that in 1967, IBM's market cap was approximately 3.3% of US GDP.
That seems much more reasonable to me. Although IBM owned much more of the market for computers than Apple does, the role of computers in society has expanded drastically. E.g., there was no consumer computer market at all in 1967.
P.S. MSFT’s 1999 high of $620.6 billion represented 6.5% of 1999's US GDP.
Thank you I was unaware. I thought it looked quite high but decided not to check. Your explanation also didn't occur to me I rationalized it away with their monopoly position but of course the IBM monopoly must have been worth less than the MSFT monopoly given the enormous expansion in market size.
If we correct the error, we conclude that in 1967, IBM's market cap was approximately 3.3% of US GDP.
That seems much more reasonable to me. Although IBM owned much more of the market for computers than Apple does, the role of computers in society has expanded drastically. E.g., there was no consumer computer market at all in 1967.
P.S. MSFT’s 1999 high of $620.6 billion represented 6.5% of 1999's US GDP.