DDQ. Also known as Due Diligence Request List. A questionnaire given by a potential buyer or investor to the company they are contemplating buying or investing in. The questionnaire is designed to obtain certain documents, records and information from the target so that the buyer or investor can conduct Due Diligence on it. The form of the questionnaire, and the information it intends to flush out from the target, will vary depending on the type of company, how long it has existed, what industry it is operating in and where it is located.