ETFs and Mutual Funds: What Dual Share Classes Could Mean for Investors

The ETF universe now exceeds $20 trillion in assets, driven by a decade‑long streak of net inflows. Within this expanding landscape, dual share classes have emerged as a structural innovation that lets a single portfolio be accessed either through an exchange‑traded fund or directly at net asset value like a mutual fund. This hybrid model, first enabled by a 2000 Vanguard exemption and revived under the SEC’s Rule 6C‑11 for active strategies, promises to streamline product offerings while preserving the distinct trading characteristics of each wrapper.

Dimensional Fund Advisors leveraged the dual‑share framework to launch the industry’s first active ETF share class attached to its U.S. microcap mutual fund. By bundling the same underlying holdings into both an ETF and a mutual fund, Dimensional expects economies of scale to compress expense ratios, while in‑kind creation‑redemption mechanisms boost tax efficiency for taxable investors. The microcap focus addresses a market need for diversification away from the “Mega‑7” concentration in large‑cap equities, offering a historically under‑weighted segment that has delivered strong risk‑adjusted returns. After securing SEC exemptive relief in 2023, Dimensional’s approval set a template that more than 80 managers have since followed, signaling a broader industry shift toward flexible, cost‑effective access.

From an operational standpoint, the dual‑share design leaves primary and secondary market mechanics largely unchanged: mutual‑fund investors transact at end‑of‑day NAV, while ETF investors trade on exchanges with authorized participants handling in‑kind or cash creations and redemptions. This duality also creates new liquidity pathways, as portfolio managers receive both cash and securities, enhancing rebalancing flexibility. Although current class exchanges require a manual process, Dimensional is working toward automated transfers that could further simplify investor experience. As more firms adopt the model, the market anticipates tighter spreads, deeper liquidity, and a more intuitive product lineup for advisors and retail investors alike.