A client asked me if I have access to historical stock prices by date. Most historical stock prices are done by symbol. This means, if the company crashed a few years back, you won't find the list of stock prices for the lifetime of the stock because the symbol is not listed anymore.
I never really paid too much attention to this, but analysis on this type of data is flawed because it carries the bias of stock survival. So if you are testing a hypothesis, you can't test against the failed or acquired companies. By default, the hypothesis will tend to be positive because the companies analysed survived without testing against the ones who failed.
any ideas where to get stock prices by date? Even Yahoo is by symbol.
I heard Ameritrade or another one has a way to do backward hypothesis testing. I wonder if they offer all the historical data even if the symbol is not listed anymore.
Got to get my hands on some of these relationships:
Reuters is a great data provider with great API:
https://customers.reuters.com/Home/RMDS.aspx
There is also amazing software by niche players focused on doing backward hypothesis verification.
