[dsomers]

IIRC the book ‘Common Sense on Mutual Funds’ has data going that far back with charts. I believe the period from the start of the 20th century until the 70s had similar inflation adjusted returns. However, for the early data I think it was really just measuring the largest companies in the country that made up the original Dow. Although, the author argues that’s a fine comparison because the 30 largest companies in the country represent the large majority of the top 500 index in terms of cap today— he further argues that over the long term small cap and large cap stocks give similar returns regardless.