Skip to main content

Assets Under Management (AUM)

What is Assets Under Management (AUM)?

The total market value of the investments a fund or asset manager holds on behalf of investors, a common measure of a fund's size.

Overview

Assets under management (AUM) is the total market value of the investments a fund or asset manager holds on behalf of its investors. For an ETF or mutual fund, AUM is the most common measure of the fund's size.

AUM rises and falls every trading day as the value of the holdings changes and as investors buy or redeem shares. The term is used at two levels: a single fund's AUM, and a firm's AUM across all the funds and accounts it manages.

Also Known As: Fund Size, Total Net Assets, Funds Under Management (FUM)

Formula

AUM = Total Market Value of Fund Assets

For a fund, often reported as Net Asset Value per Share × Shares Outstanding

Formula Components:

Market Value of Holdings
Stocks, bonds, and other securities valued at current market prices
Cash and Equivalents
Cash the fund holds for redemptions, pending purchases, or distributions
NAV × Shares Outstanding
The per-share value of the fund multiplied by the number of fund shares in issue, which gives total net assets

Definitions vary: There is no single standard for what counts. Some firms report total assets, others report net assets after liabilities, and firm-wide figures may or may not include advisory accounts or assets they only administer. Compare AUM figures from the same source.

Calculation Example

A hypothetical ETF at the end of a trading day:

Fund ABC - Fund Data:

Net Asset Value per Share$100.00
Shares Outstanding50 million

Starting AUM

AUM = $100.00 × 50,000,000

= $5.0 billion

One year later

Market gain of 8%: $5.0B × 1.08 = $5.4B

Net inflows from new investors: + $0.3B

= $5.7 billion

Result: AUM grew by $0.7 billion, or 14%, but only $0.3 billion came from new money. The other $0.4 billion was market performance. Separating flows from returns shows whether investors are actually choosing the fund.

How to Interpret

AUM is not a measure of performance or quality. It is a measure of scale, which affects a fund's costs, trading, and staying power.

General Guidelines:

Large, Established Funds

Larger funds can spread fixed costs over more assets, which supports a lower expense ratio, and they usually trade more often, which tends to mean tighter bid-ask spreads.

Mid-Sized or Specialized Funds

Often perfectly workable, especially in narrower segments. Check trading volume and spreads before placing large orders.

Very Small Funds

Funds that fail to gather assets may not cover their costs and can be closed by the sponsor. A closure returns cash to shareholders, which can trigger a taxable event and force reinvestment.

ETF liquidity: An ETF's tradability also depends on the liquidity of the securities it holds, because authorized participants can create or redeem shares against the underlying basket. A smaller ETF holding very liquid stocks can still trade efficiently.

AUM on FinSpry

Each ETF page on FinSpry shows the fund's assets under management. In the ETF screener you can sort by AUM and filter by size bands, from under $50 million to over $200 billion. The ETF issuers table adds up AUM across each issuer's funds. To weigh size against cost, look at AUM together with the expense ratio.

Limitations

  • Mixes returns and flows: rising AUM can reflect a rising market rather than investor demand.
  • Not a quality signal: a large fund is not necessarily a better fund, and size says nothing about future returns.
  • Size can work against active funds: very large active strategies may struggle to buy or sell positions without moving prices, especially in small-cap stocks.
  • Inconsistent definitions: firm-wide AUM in particular is calculated differently from one manager to another.

Related Fund Metrics

These terms are closely linked to a fund's size:

Net Asset Value (NAV)

The per-share value of the fund. NAV multiplied by shares outstanding gives total net assets.

Expense Ratio

The annual fee as a percentage of assets. The manager's fee revenue is roughly AUM × expense ratio.

Shares Outstanding

For ETFs, the share count changes as shares are created or redeemed, which moves AUM along with it.

Market Capitalization

The company-level counterpart: share price times shares outstanding for a stock.

Use This Metric

Sort and filter ETFs by assets under management to compare funds of similar size.

Screen ETFs by AUM

More in Cash Flow & Investment Analysis

Earnings power, cash generation, and the time value of money.

Explore all Cash Flow & Investment Analysis
Back to Glossary