Certificates issued by a US depository bank, representing foreign shares held by the bank, usually by a branch or correspondent in the country of issue. One ADR may represent a portion of a foreign share, one share or a bundle of shares of a foreign corporation. If the ADR's are "sponsored," the corporation provides financial information and other assistance to the bank and may subsidize the administration of the ADR. "Unsponsored" ADRs do not receive such assistance. ADRs are subject to the same currency, political, and economic risks as the underlying foreign share. Arbitrage keeps the prices of ADRs and underlying foreign shares, adjusted for the SDR/ordinary ratio essentially equal. American depository shares (ADS) are a similar form of certification.