A depositary receipt (DR) is a physical, negotiable certificate that represents ownership of shares in an overseas company that is held in custody in the issuer's home market. The structure of a depositary receipt includes a ratio, which correlates the amount of underlying shares to the receipt, a well as other general terms and conditions applicable to holders. A depositary receipt can be cancelled for its underlying shares at any time. An American Depositary Receipt ("ADR") references DRs that are available in the U.S. The terms ADR and ADS (or DR and DS) are often used interchangeably.