Twenty-Nine Percent of the Money, Six Percent of the FeesThin moat

BlackRock (BLK) — moat facet

BlackRock's own filing concedes that flows in its largest asset category barely affect revenue — the cheap money is infrastructure, not business.

Institutional index assets stood at $3.7 trillion at the end of 2025 — 29% of long-term assets, producing 6% of long-term base fees1.

Institutional index, 202529%Share of long-term AUM6%Share of long-term base fees$3.7tn of assets; BlackRock notes flows here generally have a small impact on revenues
Nearly a third of the money BlackRock manages, contributing almost nothing. It is infrastructure rather than business, and the filing says so.

The pricing is a consequence of the size of the individual mandates. BlackRock's filing notes that institutional non-ETF index assignments tend to be very large, in the multiple billions, and typically reflect low fee rates2. A sovereign wealth fund awarding a $30 billion global equity index mandate runs a competitive tender among four firms who all deliver the same tracking error, and the price lands where you would expect.

There is no way to fix this and no reason to want to. This book is the reason BlackRock has the trading infrastructure, index-management capability and securities-lending inventory that it does. Securities lending revenue alone was $705 million in 20253, earned on assets whose management fee is close to nothing.

What matters for an investor is the interpretive point. Any comparison of BlackRock to a smaller manager on the basis of assets under management is meaningless, because the two firms' books are not made of the same substance. And any narrative about BlackRock's assets growing to $20 trillion should be read as a statement about market levels and institutional mandate wins, not about revenue.

BlackRock has effectively said as much: flows in institutional index products generally have a small impact on revenues and earnings4. It is an unusually candid sentence and it is buried in the middle of a business description.

Moat trajectory: Narrowing

Institutional index assignments keep arriving in larger blocks at lower rates, and 2025 brought $119 billion of net outflows on top of that. The book is enormous, contestable, and getting cheaper per dollar with every tender.

The number that tests this moat
Moat Explorer calc
Institutional index share of long-term base fees, latest quarter
5.4% in Q2 2026 ($289M of $5,383M), on $3.9tn of assets

A rising share would mean the cheapest money has started paying; a falling one, that it is leaving.

How it's calculated: Institutional index base fees / long-term base fees, Q2 2026 10-Q
Source: BlackRock, Inc. Form 10-Q, quarter ended 30 June 2026 ↗
⚠ Threats to the moat
⚠ THREAT 01
Cheap Assets Still Carry Full Costs
Six percent of the fees, all of the operational risk, and every bit of the political attention that $14 trillion attracts.
References
  1. ReportedInstitutional index assets stood at $3.7 trillion at the end of 2025 — 29% of long-term assets, producing 6% of long-term base fees
    BlackRock, Inc. Form 10-K, FY2025, Item 1 Business — share of long-term AUM against share of long-term base fees and securities lending revenue: ETFs 42% of AUM and 45% of fees; institutional index $3.7 trillion, 29% of AUM and 6% of fees, with $119 billion of net outflows "driven primarily by a single client's partial redemptions"; institutional active 19% of AUM and 24% of fees; retail 10% of AUM and 25% of fees, of which active and index mutual funds are approximately $860 billion or 70% of retail long-term AUM and approximately 70% of retail long-term AUM is in active products; equity 61% of long-term AUM and 50% of long-term base fees. "Institutional non-ETF index assignments tend to be very large (multi-billion dollars) and typically reflect low fee rates. Net flows in institutional index products generally have a small impact on BlackRock's revenues and earnings." — FY2025 · publ. February 2026 · source ↗
  2. ReportedBlackRock's filing notes that institutional non-ETF index assignments tend to be very large, in the multiple billions, and typically reflect low fee rates
    BlackRock, Inc. Form 10-K, FY2025, Item 1 Business — share of long-term AUM against share of long-term base fees and securities lending revenue: ETFs 42% of AUM and 45% of fees; institutional index $3.7 trillion, 29% of AUM and 6% of fees, with $119 billion of net outflows "driven primarily by a single client's partial redemptions"; institutional active 19% of AUM and 24% of fees; retail 10% of AUM and 25% of fees, of which active and index mutual funds are approximately $860 billion or 70% of retail long-term AUM and approximately 70% of retail long-term AUM is in active products; equity 61% of long-term AUM and 50% of long-term base fees. "Institutional non-ETF index assignments tend to be very large (multi-billion dollars) and typically reflect low fee rates. Net flows in institutional index products generally have a small impact on BlackRock's revenues and earnings." — FY2025 · publ. February 2026 · source ↗
  3. ReportedSecurities lending revenue alone was $705 million in 2025, earned on assets whose management fee is close to nothing
    BlackRock, Inc. Form 10-K, FY2025, regulation and risk factors — "BlackRock competes with investment management firms, mutual fund complexes, insurance companies, banks, brokerage firms, financial technology providers and other financial institutions"; key competitive factors "include investment performance track records, the efficient delivery of beta for index products, investment style and discipline"; in 2025 the SEC clarified guidance on when a 5% shareholder's engagement "could lead to the shareholder being considered to hold shares with the 'purpose or effect of changing or influencing control of the issuer'", noting engagement that "exerts pressure on management to implement specific measures or changes to a policy" may be considered influencing control; on proxy voting reform, "in 2025, the SEC indicated that they are considering regulatory changes related to proxy voting" and "such reforms could increase regulatory scrutiny and uncertainty for BlackRock and affect its business or operating activities"; the EU Digital Operational Resilience Act, applicable in 2025, "focuses on direct regulation of providers and users of technology and data services" and "introduced additional governance, risk management, incident reporting, resilience testing and information sharing requirements" — FY2025 · publ. February 2026 · source ↗
  4. ReportedBlackRock has effectively said as much: flows in institutional index products generally have a small impact on revenues and earnings
    BlackRock, Inc. Form 10-K, FY2025, Item 1 Business — share of long-term AUM against share of long-term base fees and securities lending revenue: ETFs 42% of AUM and 45% of fees; institutional index $3.7 trillion, 29% of AUM and 6% of fees, with $119 billion of net outflows "driven primarily by a single client's partial redemptions"; institutional active 19% of AUM and 24% of fees; retail 10% of AUM and 25% of fees, of which active and index mutual funds are approximately $860 billion or 70% of retail long-term AUM and approximately 70% of retail long-term AUM is in active products; equity 61% of long-term AUM and 50% of long-term base fees. "Institutional non-ETF index assignments tend to be very large (multi-billion dollars) and typically reflect low fee rates. Net flows in institutional index products generally have a small impact on BlackRock's revenues and earnings." — FY2025 · publ. February 2026 · source ↗
Sources
Generated September 23, 2026