Six new exchange-traded funds from SPA ETFs, a British upstart, offer U.S. investors a new twist on fundamental indexing.Unlike traditional indices, which weight companies according to their market capitalization, fundamental indexing weights companies by other kinds of criteria such as earnings, revenue or dividends. Proponents say these benchmarks capture better returns with lower volatility. SPA ETFs' MarketGrader family of ETFs differ from some other fundamentally indexed ETFs in that the constituent stocks are all equally weighted. MarketGrader, an index house in Coral Gables, Fla., applies a filter of 24 fundamental factors in four key areas -- growth, value, profitability and cash flow -- over the universe of 5,700 U.S. listed companies. Each company gets a grade and the top-graded companies land in an index. All six funds debuted on the American Stock Exchange last week. The MarketGrader 40 ( SFV), MarketGrader 100 ( SIH) and MarketGrader 200 ( SNB) are core indices based on baskets of top-rated stocks of companies of all sizes. The MarketGrader Large Cap ( SZG), MarketGrader MidCap ( SVD) and MarketGrader Small Cap ( SSK) hold the 100 top-graded stocks of their respective market-cap categories. The new ETFs are making waves in the already controversial field of fundamental indexing, thanks to MarketGrader's claim that its flagship MarketGrader 40 Index has outperformed the S&P 500 by 15.6% percentage points on an annualized basis since the beginning of 2003. That's a pretty bold claim. Even Research Affiliates Fundamental Index, or RAFI, the benchmark for the PowerShares FTSE RAFI US 1000 Portfolio ( UUP), only claims to be able to beat the S&P 500 by 2% percentage points a year. RAFI and WisdomTree are currently the leading providers of fundamentally weighted indices for ETFs in the U.S.