Indexing Redefined, Part IV: Active Management vs. RAFI

Smart Beta Content Hub Indexing Redefined, Part IV: Active Management vs. RAFI Ben Hernandez September 21, 2026 Throughout this Indexing Redefined series, we explored how traditional market-capitalization indexing ties portfolio weights directly to stock prices, creating hidden concentration risks. Furthermore, we discussed how fundamental indexing offers a disciplined alternative by weighting companies according to their real-world economic footprint. In this final installment, we address the dilemma investors face in highly concentrated equity markets. Should they turn to traditional active management to navigate index concentration, or does fundamental indexation offer a superior, systematic solution? Key Takeaways: Traditional market-capitalization indexing ties portfolio weights directly to stock prices, creating heavy mega-cap concentration risk during narrow bull markets. Empirical research from Research Affiliates debunks the myth that active managers outperform in broadening markets, showing the median active manager underperforms benchmarks in both narrow and broad environments due to high fees, cash drag, and behavioral biases. The Research Affiliates Fundamental Index (RAFI) offers a systematic solution by weighting companies according to real-world economic footprint rather than market cap, providing low-cost passive efficiency with active return potential through counter-cyclical rebalancing. See More: Active Dreams, RAFI Delivers: Active vs. RAFI Performance in Broadening and Narrowing Markets The Concentration Conundrum Since recovering from the Global Financial Crisis (GFC), the S&P 500 Index has delivered one of the strongest bull markets in modern financial history. However, this exceptional run has been accompanied by unprecedented market concentration. A small cohort of technology mega-caps driven by secular growth narratives around cloud computing, digital platforms, and artificial intelligence (AI) have captured a disproportionate share of total benchmark market capitalization. As such, the capital markets have been subjected to various acronyms and monikers like FAANG (Facebook, Apple, Amazon, Netflix, Google) or the Magnificent Seven. More recently, there is MANGOS (Meta, Anthropic, Nvidia, Google, OpenAI, SpaceX). This narrow, top-heavy market structure ultimately distorts traditional equity exposure. In a market-cap-weighted benchmark, as momentum pushes a handful of mega-caps to elevated multiples, investors become prone to greater single-stock and single-sector concentration risk. When market performance is driven by such a narrow group of FAANGs, Magnificent Sevens, or MANGOS, traditional passive portfolios are no longer able to provide genuine broad-market diversification. Broader is Better? The Active Myth In today’s current environment, there have been numerous mentions of the market “broadening out.” This indicates performance diversifying across sectors and market-cap segments as opposed to being concentrated in large-cap tech. Conventional Wall Street wisdom suggests that active managers should comfortably outperform during these times. On paper, the logic appears sound. Essentially, active managers possess the autonomy to underweight overextended mega-caps and seek out underappreciated opportunities across the broader market. Based on this narrative, active managers should thrive in broad, expanding markets because more avenues for alpha are abound as opposed to a narrow market that revolves around a handful of dominant mega-caps. Empirical research from Research Affiliates thoroughly debunks this myth. Research Affiliates analyzed multi-decade performance data across domestic and international equities. They found that the median active manager underperforms their benchmark across both narrow and broad market environments. Market breadth was measured using 12-month rolling excess returns of equal-weighted indexes versus cap-weighted peers. “Narrowing” markets were defined as those when top names lead and “broadening” markets occur when the average stock outpaces the index. In narrowing U.S. markets, the median active manager lagged by 247 basis points (bps) due to being underweight mega-cap momentum winners. In broader markets, the median U.S. manager still trailed by 66 bps, dragged down by higher management fees, cash drag, and behavioral biases like prematurely trimming winners. International and emerging markets (EM) exhibited similar patterns. Median international active managers trailed by 58 bps in narrowing markets and 75 bps in broadening markets. In fact, active management fees in these categories consistently exceed the margin of underperformance. When breaking down performance by style box, active growth managers excelled in narrow markets and active value managers led in broad markets. Still, even perfect style timing fails to rescue active management. Managers lagged simple style benchmarks during their ideal cycle