Active and Semi-Transparent ETFs
How actively managed ETFs let a manager pick stocks rather than track an index, and the compromise structures built to let them do that without revealing every holding to the world every single day.
Prerequisites: The ETF Arbitrage Mechanism, Creation Baskets and Custom Baskets
Most ETFs simply track a published index, which is why the arbitrage mechanism works so smoothly: anyone can see exactly what the fund holds and compute exactly what a fair basket looks like. An active ETF breaks that assumption — a manager is picking and choosing holdings the way a traditional mutual fund manager does, with no index to mechanically replicate.
The original design of ETFs required daily disclosure of the full portfolio precisely so that authorised participants could construct correct creation and redemption baskets. For an active manager, disclosing every holding every single day is uncomfortable: other traders can see and front-run the manager's positioning, or simply copy the strategy for free, eroding the edge the manager is paid to produce. Fully transparent active ETFs exist and are common, but they accept that trade-off directly.
Semi-transparent ETFs were built as a compromise, using one of a few approved methods (a periodically published "proxy" basket that approximates but doesn't exactly match the real portfolio, or blind trusts that verify basket accuracy without publishing full holdings) so that authorised participants can still create and redeem shares accurately without the manager's exact current positions being visible to the world in real time. Full holdings are still disclosed, just on a lag — typically quarterly, like a traditional mutual fund — rather than daily.
The trade-off for investors is a modest increase in the bid-ask spread APs are willing to quote, since they're pricing baskets with somewhat less certainty than a fully transparent fund provides — a small cost in exchange for letting active strategies use the ETF wrapper without giving away their playbook daily.
Since the SEC's 2019 rule change formally permitting semi-transparent structures, adoption has been mixed: several major asset managers converted existing mutual funds into semi-transparent ETFs specifically to gain the tax and cost benefits of the ETF wrapper, while others concluded the daily transparency trade-off wasn't worth it and simply launched fully transparent active ETFs instead, accepting that some of their positioning would be visible to competitors.
Active ETFs let a manager pick holdings rather than track an index, which breaks the assumption of full daily transparency the ETF mechanism was originally built around. Semi-transparent structures solve this with proxy baskets or verification methods that let authorised participants create and redeem shares accurately without exposing the manager's exact daily positions, typically at the cost of a slightly wider bid-ask spread.
Further reading
- SEC, Rule 6c-11 Adopting Release