iShares and the Liquidity AdvantageWide moat

BlackRock (BLK) — moat facet

Rivals matched the price a decade ago and it changed nothing, because in exchange-traded funds the product is depth, not cost.

iShares held $5.5 trillion at the end of 2025 and took in $527 billion of net new money during the year1. That is 42% of BlackRock's long-term assets producing 45% of its long-term base fees2 — the rare case where a business's largest piece is also, proportionally, one of its better-paid ones.

iShares net inflows by exposure, 2025 ($bn)$289bnEquity$175bnFixed income$35bnDigital assets$25bnCommoditiesTotal $527bn of net new money; ETFs are 42% of long-term AUM and 45% of long-term base fees
Half a trillion dollars in one year, into pools that were already the deepest in their categories.

The instinct is to explain this with fees, and the instinct is wrong. On a plain S&P 500 tracker, Vanguard, State Street, Fidelity and Schwab all charge within a rounding error of BlackRock, and several charge less. If price decided ETF market share, iShares would have lost it a decade ago.

What decides it is depth. An exchange-traded fund is two things at once: a portfolio and a security that trades. The portfolio is a commodity — anyone can buy the index. The security is not. A fund with more assets and more daily volume has tighter bid-ask spreads, deeper order books, a larger options market, and more authorised participants willing to make markets in it. For an institution moving $200 million in an afternoon, the difference between a one-basis-point spread and a five-basis-point spread swamps a two-basis-point difference in the annual fee. So the large fund stays large, and the identical cheaper fund next to it does not catch up.

This is a network effect, and it runs the way network effects run: the advantage accrues to whoever got there first with enough size, and it compounds. It is why BlackRock can hold share in a product category where the underlying intellectual property is public and the manufacturing cost is near zero.

The place it shows most clearly is fixed income, where BlackRock effectively built the category. Fixed income ETFs took in $175 billion in 20253, and they solve a problem index equity never had: individual bonds trade rarely, in blocks, over the counter. An ETF wrapper turns an illiquid basket into something that trades continuously on an exchange — so the fund is frequently more liquid than the bonds inside it. That is not a repackaging of an existing market. It is a new one, and BlackRock is the incumbent in it.

The honest limit is that liquidity moats transfer wholesale rather than eroding gradually. Nobody takes 10% of a flagship ETF's assets. But if a rival reaches critical mass in a category — as several have in specific corners — the switch happens quickly and completely, because the thing being competed for is a tipping point rather than a share.

Moat trajectory: Widening

Half a trillion dollars of net inflows in a single year, into the deepest pools in the category, deepens them further, and ETF base fees rose 38% in the year to June 2026 on 32% more assets. The same physics cut the other way in digital assets, which fell from $78 billion to $48.8 billion in the first half of 2026; the mechanism works against BlackRock wherever it is not the deepest pool.

The number that tests this moat
Moat Explorer calc
ETF share of long-term base fees, latest quarter
48% in Q2 2026 ($2,595M of $5,383M), from 45% for 2025

The ETF franchise gaining share of the fee pool is the moat compounding; a falling share at rising assets would mean price cuts.

How it's calculated: ETF base fees and securities lending / long-term total, Q2 2026 10-Q
Source: BlackRock, Inc. Form 10-Q, quarter ended 30 June 2026 ↗
Aspects of the moat
DIG DEEPER 01
The Biggest Fund Wins, and Then Keeps Winning
Two identical funds, one basis point apart, and the larger one gets larger — which is why the fee war never moved the share.
DIG DEEPER 02
The Spread Is the Product
An institution pays the spread on every trade and the fee once a year, which is why the cheaper fund keeps losing to the more liquid one.
DIG DEEPER 03
Five Hundred Billion Dollars, in One Year
BlackRock did not grow in 2025 so much as reallocate: one part grew while two shrank, and the part that grew is the part that pays.
DIG DEEPER 04
Fixed Income ETFs: A Market BlackRock Made
A wrapper more liquid than its own contents — a thing that should not be possible, and a category BlackRock built rather than entered.
⚠ Threats to the moat
⚠ THREAT 01
The Price of a Beta Product Is Already Zero
Some competitors charge nothing and can afford to forever, which sets the reference price for everything BlackRock manufactures.
⚠ THREAT 02
A Rival Reaching Scale in a New Category
Incumbency defends the products that exist and offers nothing at all in the ones being invented.
References
  1. ReportediShares held $5.5 trillion at the end of 2025 and took in $527 billion of net new money during the year
    BlackRock, Inc. Form 10-K, FY2025, Item 1 Business — iShares ETF AUM $5.5 trillion with $527 billion of 2025 net inflows: equity $289,263M, fixed income $175,328M, digital assets $34,763M, commodities $25 billion, multi-asset $1,978M; US-listed ETF AUM $3.9 trillion with $367 billion of inflows and international listings $1.6 trillion with $160 billion; equity ETF AUM rose from $3,106,398M to $4,006,014M on $580,684M of market change and $29,669M of FX, fixed income from $985,652M to $1,205,953M, digital assets from $55,306M with a negative market change; 2025 equity net inflows $220 billion overall, being $289 billion into ETFs against $55 billion and $14 billion of outflows from non-ETF index and active; fixed income net inflows $164 billion, $175 billion into ETFs and $29 billion into active; "approximately half of BlackRock's equity AUM is tied to international market strategies, including emerging markets, which tend to have higher fee rates than US equity strategies" — FY2025 · publ. February 2026 · source ↗
  2. ReportedThat is 42% of BlackRock's long-term assets producing 45% of its long-term base fees — the rare case where a business's largest piece is also, proportionally, one of its better-paid ones
    BlackRock, Inc. Form 10-K, FY2025, Item 1 Business — assets under management of $14.0 trillion at 31 December 2025 (long-term $12,960,786M plus cash management $1,080,732M); equity $7,793,875M, fixed income $3,272,021M, multi-asset $1,223,625M, alternatives $423,614M, digital assets $78,435M, currency and commodities $169,216M; five-year AUM CAGR 10%, alternatives 22%, multi-asset 13%, equity 12%, currency and commodities 17%, fixed income 4%; by style, active $3,432,743M, non-ETF index $4,060,333M, ETFs $5,467,710M; approximately 24,900 employees in more than 30 countries serving clients in over 100 — FY2025 · publ. February 2026 · source ↗
  3. ReportedFixed income ETFs took in $175 billion in 2025, and they solve a problem index equity never had: individual bonds trade rarely, in blocks, over the counter
    BlackRock, Inc. Form 10-K, FY2025, Item 1 Business — iShares ETF AUM $5.5 trillion with $527 billion of 2025 net inflows: equity $289,263M, fixed income $175,328M, digital assets $34,763M, commodities $25 billion, multi-asset $1,978M; US-listed ETF AUM $3.9 trillion with $367 billion of inflows and international listings $1.6 trillion with $160 billion; equity ETF AUM rose from $3,106,398M to $4,006,014M on $580,684M of market change and $29,669M of FX, fixed income from $985,652M to $1,205,953M, digital assets from $55,306M with a negative market change; 2025 equity net inflows $220 billion overall, being $289 billion into ETFs against $55 billion and $14 billion of outflows from non-ETF index and active; fixed income net inflows $164 billion, $175 billion into ETFs and $29 billion into active; "approximately half of BlackRock's equity AUM is tied to international market strategies, including emerging markets, which tend to have higher fee rates than US equity strategies" — FY2025 · publ. February 2026 · source ↗
Sources
Generated September 23, 2026