Why is Yahoo finance's historical prices so high. For example, IBM's prices in the 70s are in the $300 range. I know that there are some errors in this data, but this a trend in many of their charts. What is this price reflect? I'm sure it's not the market price in 70s dollars. Is this also an error in data before they started collecting it or does it take into account of splits or something else?
https://www.quandl.com/data/YAHOO/IBM-IBM-International-Business-Machines