On Yahoo Finance, you don't seem to be able to get any data earlier than from January second 1962, and from Google Finance, the corresponding date is December nineteenth 1980. However, General Electric has been on the stock market since at least 1896 so there has to be more than this. How can I see a company's entire historical stock data? Can I get that data for free somehow or do I have to pay for it?
AFAIK you have to pay for it. See geekflare.com/best-stock-market-api or you can use web-scraping, but this would be very advanced web-scraping.– Daniel FDec 20, 2020 at 22:10
Do realize that before 1962 you are in the pre-computer age. Prior to the digital era, people had to use metropolitan or institutional libraries for research.
From this Zack's article on historical stock prices, once source would have been the "Standard & Poor's Daily Stock Price Record" which seems to have started in 1962 for NYSE and AMEX stocks, 1968 for NASDAQ/OTC. I would not be surprised if Standard & Poor's data is the source of what you find online.
Other sources include "The Commercial & Financial Chronicle/Bank & Quotation Record" which provides stock records from 1928 to 1987, and microfiche/microfilm copies of the "Wall Street Journal" assuming your stock is significant enough by the WSJ to be printed.
Also while General Electric has been a central ongoing entity, other companies have been subject to mergers, spin-offs, and acquisitions. The NYPL blog post on historical stock prices goes over the difficulty of getting prices for Macy's/Federated Department Stores and Del Monte Foods beyond a certain point due to corporate actions.
TLDR: If you want full price histories with corporate actions, you'll probably have to pay.