American Depositary Share - ADS

A U.S. dollar-denominated equity share of a foreign-based company available for purchase on an American stock exchange. American Depositary Shares (ADSs) are issued by depository banks in the U.S. under agreement with the issuing foreign company; the entire issuance is called an American Depositary Receipt (ADR) and the inpidual shares are referred to as ADSs.

Depending on the level of compliance with U.S. securities regulations the foreign company wishes to follow, the company may either list its shares over-the-counter (OTC) with low reporting requirements or on a major exchange like the NYSE or Nasdaq. Listings on the latter exchanges generally require the same level of reporting as domestic companies, and also require adherence to GAAP accounting rules.

Taobiz explains American Depositary Share - ADS

Foreign companies that choose to offer shares on U.S. exchanges gain the advantage of a wider investor base, which can also lower costs of future capital. For U.S. investors, ADSs offer the opportunity to invest in foreign companies without dealing with currency conversions and other cross-border administrative hoops.

Even though ADSs repsent real claims to foreign shares (and could be converted if the investor wished to do so), there is currency risk involved in holding them. Fluctuations in the currency exchange rate between the USD and the foreign currency will affect the price of shares as well as any income payments, which must be converted into U.S. dollars.