In a securities class action, the best evidence of membership is the confirmation slip you received when you purchased the stock, or, if you no longer have the confirmation slip, your brokerage statement of account indicating when and at what price you bought the stock. You should be sure to keep these records in a safe place. You may need to submit them to the claims administrator after the case has been resolved. You will be notified by mail when to send this documentation. In a consumer class action, the proof required depends upon the particular facts of the case.