Index funds & ETFs
How to evaluate the suitability of actively managed ETFs versus passive index funds for core portfolio holdings.
This article examines the core distinctions between actively managed ETFs and passive index funds, clarifying their roles, decision criteria, and practical implications for building durable, cost-efficient core portfolios.
Published by
Mark Bennett
July 23, 2025 - 3 min Read
In the landscape of core holdings, investors weigh two broad approaches: actively managed ETFs that seek to outperform benchmarks and passively tracking index funds that mirror market indices. The appeal of active ETFs lies in potential excess returns, tactical tilts, and responsive adjustments to changing conditions. However, active strategies come with higher expense ratios, more frequent trading, and the risk of underperforming the chosen benchmark. For a core portfolio, where consistency and cost efficiency matter most, it’s essential to assess whether the manager’s skill and process justify the fees. A clear framework helps separate investment myths from practical, evidence-based decisions.
Start by defining core portfolio goals. Are you prioritizing long-term growth, capital preservation, or a balance of the two? Active ETFs may offer diversification through nimble sector bets or factor exposures, but they also introduce style drift risk when managers adjust holdings away from broad market exposure. Passive index funds, by contrast, emphasize broad market capture with transparent holdings and lower costs. Your tolerance for tracking error, liquidity needs, and tax considerations will shape whether a manager’s edge is worth paying for. A careful goal-setting process anchors every later choice.
Alignment with portfolio design and risk budgets.
A practical evaluation starts with manager skill and the persistence of outperformance. Look for a documented, repeatable investment process, backed by transparent disclosures, performance relative to a benchmark, and an explicit edge thesis that extends beyond luck. Evaluate the asset class coverage, turnover frequency, and the rate at which the fund’s fees erode returns. Consider whether the ETF’s creation/redemption mechanism affects tax efficiency and tracking accuracy under different market regimes. Scrutinize historical drawdowns during bear markets and how the strategy performed when liquidity tightened. An edge that vanishes in stress moments loses practical value for core holdings.
Another crucial factor is cost transparency and the structure of the ETF. Compare expense ratios, trading costs, and bid-ask spreads within the context of expected turnover. The compounding effect of higher fees can erode any potential alpha over time, especially in a core sleeve designed for decades of growth or stability. Passive funds deliver predictable costs and simple replication, while active funds embed complexity through frequent rebalancing. Examine the fund’s tax efficiency, potential capital gains distributions, and how the ETF awards or discloses its tracking error versus the benchmark. These practical details determine whether outperformance is an exception or a repeatable advantage.
Scenario planning: bear markets, rising rates, and regime shifts.
When integrating either option into a core portfolio, assess alignment with risk budgets and diversification goals. Passive index funds provide broad, low-cost exposure to markets, which helps stabilize overall risk through wide diversification. Active ETFs can tailor exposures to specific sectors, themes, or factor tilts that might complement other holdings, yet they may introduce concentration risk or unintended bets. The key is to map each prospect to a concrete risk budget, ensuring the core remains anchored by low-cost, broadly diversified assets while satellites or sleeves explore potential alpha opportunities. Maintain discipline by limiting the portion of core exposure allocated to more speculative active bets.
Consider liquidity, trading efficiency, and operational practicality. Passive funds typically offer deep liquidity, tight spreads, and predictable settlement patterns, making them easier to trade at scale. Active ETFs may still provide liquidity but can exhibit wider spreads during volatile periods or in less liquid asset classes. Operational considerations—such as fund onboarding, reporting cadence, and the quality of trade execution—can influence net performance. In a core rollout, prefer combinations that minimize operational friction while preserving the ability to rebalance efficiently. Align your execution practices with the fund’s structure to avoid unintended tracking errors or cost leaks.
Tax efficiency, regulatory considerations, and reporting.
Scenario planning helps illuminate where active or passive options add resilience. In severe drawdowns, broad-based passive exposure often consolidates losses in a predictable, diversified manner, offering smoother recovery when markets rebound. Active strategies may outperform in certain regimes if managers navigate sector rotations adeptly, yet they risk underperforming when their bets fail to materialize. The core objective is to endure volatility without excessive costs or drift from long-term targets. Build a framework that tests outcomes under different scenarios, including rate moves, inflation surprises, and geopolitical shifts. If an edge depends on transient conditions, its relevance for core holdings is questionable.
A disciplined approach uses backtesting, though with prudence. Backtests can reveal whether a strategy would have survived past cycles, but they cannot guarantee future results, especially for active bets that hinge on manager decisions. In addition to simulated performance, examine the transparency of the investment process, including how decisions are made, what triggers trades, and how frequently risk controls are applied. Ultimately, a core portfolio benefits from reliability, predictability, and cost containment; any edge must demonstrate durability across market environments and align with investor time horizons.
Practical guidance for building a durable core with confidence.
Tax efficiency matters for core holdings because it affects after-tax returns over long horizons. Passive index funds typically distribute fewer capital gains, benefiting taxable accounts and retirement plans alike. Active ETFs may generate higher turnover and, consequently, more taxable events, though some managers optimize tax-lot management and harvest tax losses. Regulatory and disclosure standards are also important. Understand the fund’s reporting cadence, how holdings are disclosed, and whether the ETF employs derivatives or leverage in ways that affect risk and transparency. A clear understanding of these factors helps ensure the core portfolio remains tax-efficient and compliant under evolving rules.
Risk management and monitoring frameworks are essential. Establish clear triggers for rebalancing, including tolerance bands for tracking error, diversification, and risk concentration. Passive funds simplify risk monitoring because they reflect a defined index; however, no index is risk-free. Active strategies require ongoing oversight to ensure managers stay aligned with stated objectives and risk controls. Implement regular performance reviews, independent attribution analyses, and a governance process that weighs fees against potential alpha. A robust monitoring framework helps protect the core from creeping costs, drift, or misalignment with the investor’s plan.
For most investors, a durable core leans toward low-cost, broadly diversified passive exposure as the backbone. Active ETFs can play a supporting role by providing targeted tilts, hedging, or opportunistic bets, but these should be sized conservatively within the core framework. Begin with a foundational set of broad market index funds, then consider a measured allocation to select active ETFs that offer transparent methodologies and a proven process. Regularly review the rationale behind each active addition, re-evaluate costs, and monitor performance relative to appropriates benchmarks. The objective is consistency, not speculation, ensuring the core remains resilient across market cycles.
In practice, the best approach blends discipline with selective tact. Investors benefit from avoiding over-concentration in any single active conviction and from prioritizing cost discipline and tax efficiency. A core portfolio built on passive foundations with a measured inclusion of actively managed ETFs can provide both stability and the potential for incremental gains. The key is ongoing education, transparent decision-making, and a willingness to adjust allocations as costs, performance, and macro conditions evolve. With a clear framework, a core portfolio can endure, adapt, and thrive over long horizons.
