The fund tracks the S&P MidCap 400 Revenue-Weighted Index. It builds its portfolio from the constituents of the S&P 400, weighting each stock by its combined revenue over the past four quarters. The core idea is to set aside price bubbles and focus on real top-line growth.

It suits value investors who want to pursue long-term excess returns by selecting undervalued, high-quality mid-cap companies rather than following a traditional mid-cap index.

Launched by Invesco in 2008, it is a passively managed ETF that tracks an index.

By assigning higher weights to companies with larger revenue, the fund tends to hold value-type stocks with low price-to-earnings (P/E) or price-to-sales (P/S) ratios in its top positions. To prevent concentration in any single stock, individual position weights are capped at a certain level.

• Eliminates the risk of overweighting overvalued stocks, a drawback of market-cap weighting
• Transparent management based on revenue, an objective fundamental metric

Assets under management (AUM) stand at $1.3B, and the expense ratio is 0.39% per year.

Compared with FNDX and PRF, which use similar fundamental strategies, it is more specialized in the mid-cap segment. Compared with IJH, a general mid-cap ETF, it shows a clear tilt toward the value style.

Mid-cap companies backed by solid earnings have delivered steady results, and the fund has held up relatively well during periods of market volatility. It has performed especially well during value rallies.

Investors fatigued by a market skewed toward growth stocks have turned to smart beta products that emphasize actual revenue, and this has produced steady fund inflows.

Its strength is a rational investment approach based on the real scale of companies. However, investors should note that the weight of companies with large revenue but low profit margins can rise.

JHMM and RECS, shown in the table, are mid-cap alternatives based on multi-factor and research-driven approaches, respectively. For conventional mid-cap investing, IJH, IVOO, and MDY are representative choices, and for a somewhat broader mid-cap exposure, IWR is also worth considering. If you want value investing across the entire market, you can adjust your allocation by considering VTI as well.

These are the key items to review before investing in the RWK ETF. It is important to fully understand the distinctive return structure of revenue weighting.

Companies that generate revenue but suffer deteriorating profitability can remain in the portfolio, so you should regularly check the results of the quarterly rebalancing and the financial health of the holdings.

It is a smart beta solution suited to long-term investors who want to overcome the limits of market-cap weighting and invest in US mid-cap stocks based on the actual economic size of companies.