Foreign stocks that trade on U.S. exchanges are outperforming their domestic counterparts.

The Bank of New York Mellon Composite ADR Index outperformed the S&P 500 by 7.2 percentage points, +9.9% to +2.7%, for the first six months of 2009. During this same time period, the average return for all U.S.-listed ADRs has been +24%. (This includes pink sheet-listed companies that are excluded from the ADR index.)

An proxy for shares held in trust in a foreign bank. The receipts are traded in the United States on the NYSE, Nasdaq or American Stock Exchange.

The Bank of New York Mellon Composite ADR Index includes all 353 ADRs listed on the NYSE and Nasdaq. European companies account for 63% of the index, followed by Asia at 26% and Latin America at 9%. The index’s largest members are global giants like BP (NYSE: BP), HSBC (NYSE: HBC), Total (NYSE: TOT), Toyota (NYSE: TM), and Vodafone (NYSE: VOD).

While many of the largest and most prestigious ADRs have spots in the ADR Composite Index, many of this year’s best performers were smaller firms, including several that trade OTC (and are not part of the index).

Of the top ten ADRs, four are Chinese and the others come from Australia, Great Britain, Korea, Italy, Ireland and Hong Kong. The average market cap is $649 million — much smaller than average market cap for the ADR Index’s market cap of $11 billion.

OZ Minerals (OTC: OZMLY.PK) is an Australian mining company that has gained +290% so far this year, largely on the back of a shareholder-approved sale of $1.39 billion of mines to China Minmetals Corp. The move eliminated its debt.

British department store Debenhams (OTC: DBHMY.PK) has gained +279% in the first half of 2009. Much of the gains came when the company announced a better-than-expected rise in fiscal first-half profit and boosted sales in the most recent quarter.

Webzen (NASDAQ: WZEN) saw its shares rise +278% in the first half of 2009. The Korean online games developer got a boost when it signed an agreement with U.S.-based Red5 Studio for publishing rights to the game “T-Project” — one of the most promising new online games by some of the developers of World of Warcraft — in the United States and Europe.

Chinese television advertising company China Mass Media (NYSE: CMM) gained +232% from Jan. 1 to June 30. The company saw much of these gains on the announcement that its net first-quarter profit rose +250% from the fourth quarter.

KongZhong (Nasdaq: KONG) is a Chinese mobile phone entertainment and services company whose shares rose +198% in the first half of the year. Much of the action centered on guidance and results that continually beat expectations. The company’s total revenues blew past expectations, leaping +38% year-over-year.

Italian biopharmaceutical company Gentium (Nasdaq: GENT) has posted a +192% gain so far this year on its better-than-expected first-quarter results. The company’s net losses shrank to 2.96 million euros, vs. 6.1 million euros for the same period last year, thanks to tightening operating costs and reduced spending on R&D.

VanceInfo Technologies (NYSE: VIT) is a Chinese IT services provider that has seen its shares rise +181% since the first of the year. The company had $3.8 million in net income in the first quarter of 2009, up 26.6% year-over-year. Revenue rose +46.8% from the previous year.

Irish medical diagnostics company Trinity Biotech (Nasdaq: TRIB) has gained +170% so far in 2009. Investors rewarded the company for more than doubling its earnings per share, to $0.12 from $0.055.

China GrenTech (Nasdaq: GRRF), a Chinese manufacturer of wireless products, gained +169% in the first six months of 2009 on the back of its first quarter earnings announcement. Total revenue increased by +299.6% year-over-year, and gross profit increased by +232.8% year-over-year.

Hong Kong electronics company Techtronic Industries (OTC: TTNDY.PK) saw its shares rise +165% in the first half of the year, well outperforming the Dow Jones Hong Kong Index, which gained just +34% over the same period.