Reading Custody-Bank 13F Filings: BNY Mellon & State Street

State Street Corp filed a $2.98T 13F in Q4 2025. Bank of New York Mellon filed $568B. JPMorgan Chase filed $1.59T. Bank of America filed $1.37T. Reading those numbers without understanding what they represent leads to one of the most expensive misreads available in 13F data: treating custody-bank 13F filings as if they were institutional conviction holdings.

They are not. Custody banks file 13Fs based on intermediary positions held in their custody and securities-services platforms, weighted to where their institutional clients' capital actually sits. The custody-bank 13F is a real and useful signal — but it is a different signal from what a discretionary active manager's 13F captures.

What a Custody-Bank 13F Actually Reports

A custody bank operates as the institutional intermediary between asset owners (pension funds, endowments, sovereign wealth funds, mutual fund complexes, individual investors via wealth platforms) and the equity markets. The bank does not own the underlying equities in any meaningful economic sense. The asset owners own them. The custody bank holds them on its books as an intermediary, provides settlement and corporate-actions services, and reports them in its 13F because the bank is the registered holder of record under SEC rules.

Three implications follow:

• Concentration mirrors index weighting. Because custody platforms aggregate institutional capital across many asset owners, the resulting 13F looks roughly like an index — heavy in mega-cap tech (NVDA, AAPL, MSFT, AMZN, GOOGL), broad across long-tail names, low concentration relative to the active conviction sector.
• Position changes lag client allocation decisions. When an institutional client moves capital between asset managers, or when an asset manager rebalances a portfolio, the underlying equities flow through the custody bank's books. The bank's 13F reflects net flow at the reporting date, but the decision to allocate happened upstream and earlier.
• Reported AUM is not portfolio AUM. Total reported AUM for a custody bank includes cash, fixed income, non-US equities not subject to 13F reporting, and other asset classes. The 13F-reportable holdings are a subset.

The Five Major US Custody Banks

For 13F-driven analysis, the major US custody filers are:

• State Street Corp ($2.98T 13F-reportable AUM) — the largest US custody platform by 13F-reported holdings. Anchors institutional pension and asset-manager intermediation. See State Street's 13F holdings →
• Bank of New York Mellon Corp ($568B 13F-reportable AUM) — a major custody platform with deep wealth-management and securities-services integration.
• JPMorgan Chase & Co. ($1.59T 13F-reportable AUM) — combines custody, asset management (J.P. Morgan Asset Management), private banking, and broker-dealer activity into one 13F filer. See JPMorgan's 13F holdings →
• Bank of America Corp ($1.37T 13F-reportable AUM) — combines retail brokerage (Merrill), institutional custody, and asset management.
• Wells Fargo & Co. ($549B 13F-reportable AUM) — wealth-platform-driven, with custody for advisory clients dominant.

Each filer combines true custody activity with some discretionary asset management. Reading the filing well requires understanding the proportions, which differ by filer.

The Custody Signature vs Active Signature

Three positional signatures distinguish custody flow from active conviction in the same 13F:

• Top 10 weight near 30% (custody) vs 40-60% (active). Custody platforms naturally diversify across asset-owner allocations; the top 10 lands near index weight. Active discretionary managers typically concentrate the top 10 well above index weight.
• ETF inventory positions. Custody platforms hold ETF shares (IVV, VOO, SPY, QQQ) at material size because their advisory clients hold ETFs. Active discretionary managers rarely hold these instruments at meaningful percentages of their book.
• Held-roughly-flat status across most top positions. Custody platforms see net client flow drive position-level changes, but the magnitudes are smaller than discretionary manager rotation. Most top positions tagged 'Held roughly flat' is the expected custody signature.

BNY Mellon's Q4 2025 13F file is a textbook custody example: top 8 positions all 'Held roughly flat,' IVV at 1.86% reported weight, and total top 10 weight near 30%. Compare to a fundamental active manager like Dodge & Cox, where the top 10 holds approximately 27% of the book but with active position management visible across multiple top names (SCHW -8%, CVS -15%, BKNG +8%).

How to Use Custody-Bank 13Fs Productively

Custody-bank 13Fs are most useful as cross-check signals on flow narratives seen elsewhere. Three concrete applications:

• Confirming institutional rotation. When BlackRock active sleeves and Wellington Management both add to a name (for instance, a META rebuild during late 2025), and BNY Mellon's custody platform also shows the same name with +9% share count, the custody confirmation tells you the rotation is broad-based across institutional capital, not isolated to specific active managers.
• Identifying broad sector flows. Custody platforms naturally aggregate sector flows across their entire client base. A custody-bank 13F showing rising weight in a single sector (banks, utilities, healthcare) is a clean read on broad institutional sector rotation.
• Spotting unusual concentration changes. When a custody platform's 13F shows a meaningful weight change (5%+ of share count) on a position that is normally flat, the underlying client flow event is meaningful. Either a major asset manager re-allocated capital, or a single asset owner made a large-scale move, or a corporate event changed share-counts mechanically.

Two Common Misreads

The first misread is treating custody-bank 13F position size as a buy signal. Seeing $26B of MSFT in BNY Mellon's filing and $25B of AAPL is not BNY Mellon recommending MSFT or AAPL — it is the natural index-weight result of the custody platform aggregating institutional capital that holds those names through diverse asset-manager allocations.

The second misread is using custody-bank 13Fs as proxy for retail flow. Custody banks predominantly intermediate institutional capital, not retail. Retail flow into mega-caps shows up first in market-maker and ETF flows, not in custody-bank 13F filings. The custody-bank read is institutional-flow-weighted by definition.

The Filer-Type Classifier

13F Insight tags filers with filer_type codes that segregate custody-driven holdings from active conviction money. The classifier identifies State Street, BNY Mellon, and similar custody platforms separately from active fundamental managers, market makers, and pure passive index complexes. This tagging enables reading 13F holder files with custody flow filtered out — leaving the discretionary active conviction signal cleaner.

For investors using 13F data as a research input, the tier of custody-bank filings is the cleanest cross-check available on broad institutional sector rotation. Browse all top-tier filers and their classifications →.