It seems that every day a new ETF is listed with a new twist on an index.

So, for a short history in ETF evolution:

1. First came the market-weight indexed ETFs. These were ETFs that benchmarked themselves to indices like the S&P (AMEX: SPY) or the Nasdaq (NASDAQ: QQQQ).

2. Then, Jeremy Siegel and the WisdomTree (WSDT) team introduced dividend -weighted indices. Instead of giving commensurate weight to the largest companies in an index, these ETFs looked at companies with the highest payouts in terms of dividends. These were shortly followed by earnings-weighted indices and the ETFs that track them.

3. Now, we read on MarketWatch that a new firm named RevenueShares has listed three separate shares: the RevenueShares Large Cap Fund (NYSE: RWL), the RevenueShares Mid Cap Fund (NYSE: RWK), and lastly, you guessed it, the RevenueShares Small Cap Fund (NYSE: RWJ).According to MarketWatch, "Rather than create its own indexes, RevenueShares weight several existing Standard & Poor's benchmarks by sales."

How well does revenue-weighting work for long-term performance?
The firm claims that the back-tested results going back to the early 1990s for the large-cap fund have outperformed the regular S&P 500.

I would have liked to see a longer historical period than just the last 17 years, but what do I know? I'm just an old-fashioned earnings-weighted indexer.

Zack Miller is the managing editor of IsraelNewsletter.com and a former equity analyst for a leading multinational hedge fund.