Russia Combines Oil and Gas (The Motley Fool) The Motley Fool - The invention of the American depositary receipt (ADR) was both a boon and a curse to U.S. investors. On the one hand, when foreign companies list their shares on U.S. exchanges, they make it a heck of a lot easier for the average investor to buy a piece of Nokia (NYSE: NOK - News), Cable  amp; Wireless (NYSE: CWP - News), or SAP AG (NYSE: SAP - News) than it would have been if she had to figure out how to buy shares on the Helsinki, London, or Munich stock exchanges. But on the other hand, there are the -- to put it politely -- "inefficiencies" of buying ADRs.