So you found an old stock certificate in your attic, or a relative's paper records. Does it have any value? Is the owner entitled to shares of a company that still exists? How do I research the history of the company that issued the shares, to determine what the stock certificate is worth today?
There are several options available for you. You can use the Capital Changes database, available for free from the New York Public Library with an active NYPL card, to research the history of the company, and its successors, if there are any. You can contact the Corporations office of the state in which the company was incorporated, which will be stated on the certificate. There is also the possibility, even if the company no longer exists and has not be absorbed by a successor, that the certificate may have some value as a collectible.