That's technically what I'm using, however, if you look at the S&P 500 historic data - http://finance.yahoo.com/q/hp?s=%5EGSPC+Historical+Prices http://finance.

That's technically what I'm using, however, if you look at the S&P 500 historic data - http://finance.yahoo.com/q/hp?s=%5EGSPC+Historical+Prices http://finance.yahoo.com/q/hp?s=%5EGSPC+Historical+Prices - the Adj. Close is the same as actual close (meaning there's never dividends or splits to account for). That Adj. close is what the main site - http://stockchoker.com/ http://stockchoker.com/ - uses for all symbols, so for pretty much everything else, splits and dividends are accounted for... but nothing else I've found goes back anywhere close to 1950 (and is also representative of the stock market as a whole). So that's why I'm leaning toward still using the S&P500 data, but adding an "average" dividend payout each year (which I'll do some research on.. guessing a little over 1% a year).