Understanding AUM in 13F Filings: What It Includes and Excludes

What Is AUM in a 13F Filing?

Assets Under Management (AUM) in the context of 13F filings is the total market value of all equity positions reported on a given filing date. When 13F Insight shows a filer like Vanguard with "$6.9 trillion in AUM," that's the sum of all holdings at quarter-end market prices.

But this number requires careful interpretation. 13F AUM is not the same as total assets managed by the firm.

What 13F AUM Includes

U.S.-listed equity securities (stocks and ETFs)
Equity options and certain convertible securities
ADRs (American Depositary Receipts of foreign companies listed in the U.S.)
Positions valued at quarter-end market prices

What 13F AUM Excludes

Bonds and fixed income — a firm managing $2 trillion in bonds won't show any of that on a 13F
Non-U.S. listed equities — shares traded only on foreign exchanges
Private equity and real estate — illiquid assets not reportable on 13F
Cash and money market — not a 13F-reportable security
Short positions — 13F only captures long positions
Derivatives (most types) — swaps, futures, and many structured products

Why AUM Comparison Requires Context

Comparing 13F AUM across different types of filers can be misleading:

Filer Type	13F AUM vs Total AUM	Example
Index equity manager	13F AUM ≈ total equity AUM	Vanguard ($6.9T 13F, ~$10T total including bonds)
Bank custodian	13F captures managed equity only	BNY Mellon ($568B 13F, $53T+ in custody)
Hedge fund	13F shows long equity book only	Citadel ($666B 13F, significant non-equity positions excluded)
Insurance company	13F excludes fixed income portfolio	Bond-heavy insurers may have small 13F relative to total assets

AUM Changes: What Drives Them?

Quarter-over-quarter AUM changes come from three sources:

Market appreciation/depreciation: If the market rises 5%, all-else-equal AUM rises ~5%. This isn't a decision by the manager.
Net inflows/outflows: New client money coming in or existing clients withdrawing. This reflects the firm's commercial success.
Position changes: Buying new stocks or selling existing ones. This reflects investment decisions.

The challenge: a 13F can't distinguish between these three. A manager showing 10% AUM growth might have 8% from market moves and 2% from inflows — or 5% each, or any other combination. Use the AUM history chart on each filer's page to see the trajectory over time.

Real Example

Schwab Investment Management grew from $433B to $644B over 8 quarters (Q1 2024 to Q4 2025). That's +48.6%. But the S&P 500 also rose significantly over that period. Without knowing Schwab's exact inflow data, we can't separate market gains from organic growth — but the magnitude suggests both contributed.

Common Misconceptions

“Higher AUM means better performance”

A fund could grow from $100B to $150B purely from client inflows while underperforming its benchmark. AUM growth is not a performance metric.

“Declining AUM means the fund is failing”

A market downturn shrinks all AUM mechanically. Check whether the fund's AUM declined more or less than the market — that's the real signal.

“13F AUM represents all assets at the firm”

It doesn't. For most filers, 13F AUM is a subset — sometimes a small fraction — of total firm assets.

FAQ

Where can I see AUM history for a filer?

Every filer detail page on 13F Insight shows an AUM history chart with up to 20 quarters of data. This is available to all users, including free tier.

Is 13F AUM reported in real-time?

No. 13F filings are due 45 days after quarter end, so the data is at least 6 weeks old when published. Markets may have moved significantly since the reporting date.

Can I compare AUM across different types of filers?

You can, but be cautious. A $500B bank custodian and a $500B hedge fund have very different portfolio characteristics despite showing the same 13F AUM number. Always consider the filer type when comparing.