RWJ is one of a handful of small-cap ETFs that approach the space with a fundamentals-weighted methodology. In this case, the component stocks are simply weighted by top-line revenue rather than market capitalization. The fund basically invests in positive revenue-producing securities of the S&P SmallCap 600, a market-cap-weighted index that consists of US small-cap companies screened for size, liquidity, and financial viability. The index defines a constituents revenue by the sum of its most recently reported trailing four-quarter revenues. Constituents with higher revenues are more heavily weighted. The index rebalances quarterly so that no individual constituent exceeds 5% weight. Prior to June 4, 2018 the funds underlying index was called OFI Revenue Weighted Small Cap Index.