---
title: "Assets under management (AUM)"
description: "Assets under management is the total market value of the assets a fund holds, net of liabilities, reported either for the whole fund or for a single share class."
canonical: https://fundfactsapi.com/glossary/aum
published: 2026-09-04
updated: 2026-09-04
publisher: FundFacts API
---

# Assets under management (AUM) (AUM, Fund size, Net assets, Total net assets)

> Assets under management is the total market value of the assets a fund holds, net of liabilities, reported either for the whole fund or for a single share class.

## Definition

**Assets under management (AUM)**, also called fund size or total net assets, is the value of everything a fund owns (securities, cash, derivatives at market value) minus what it owes. Fund houses publish it on the factsheet as of a given date, in the fund's base currency. A fund with several share classes typically reports both a fund-level AUM and a per-class figure.

## Why it matters

Fund size affects liquidity, cost efficiency and viability. Very small funds can carry proportionally higher fixed costs and are more likely to be merged or closed; very large funds in narrow markets can find it harder to trade. For ETFs, AUM is also a rough proxy for secondary-market liquidity. Screeners commonly use minimum AUM thresholds, and client reports show it as a basic fact.

## In the API

AUM appears in `keyFacts.aum` and again in `headlineMetrics.aum`. Values are numeric, in the currency given by `keyFacts.currency`, as of `dataAsOf`. Example values:

```json
{
  "keyFacts": { "aum": 78500000000, "currency": "USD" },
  "headlineMetrics": { "aum": 78500000000 },
  "dataAsOf": "2026-07-31"
}
```

## Common pitfalls

Three things trip up comparisons. First, currency: convert before ranking funds with different base currencies. Second, scope: some documents report share-class assets, others fund-level or even umbrella-level totals, so check what the factsheet states. Third, date: AUM moves daily with flows and market prices, so always display `dataAsOf`. Manager-level AUM (a firm's total) is a different figure altogether. See [NAV](https://fundfactsapi.com/glossary/nav) and the [fund screener](https://fundfactsapi.com/use-cases/fund-screener) use case.

## In the FundFacts API payload

- `keyFacts.aum`
- `headlineMetrics.aum`

## About FundFacts API

FundFacts turns any fund or ETF ISIN into one dated factsheet (fees and KID costs, the 1–7 risk indicator, holdings, sector and country exposure, returns) read from the fund house's own documents: as a client-ready PDF under your firm's name for advisers and wealth managers, as JSON through its API for developers, or inside ChatGPT and Claude through its MCP server.

FundFacts works inside ChatGPT and Claude as a connector (a remote MCP server): ask about any fund or ETF by ISIN, ticker or name and the assistant answers from FundFacts' dated figures, fees, risk, holdings, exposure and returns, with fund cards, side-by-side comparisons, holdings overlap and portfolio look-through.

- Free API key, no card: https://fundfactsapi.com/signup
- Documentation: https://fundfactsapi.com/docs (OpenAPI: https://fundfactsapi.com/openapi.json)
- MCP server: https://fundfactsapi.com/api/mcp (set-up for every client: https://fundfactsapi.com/mcp-server)
- Pricing: https://fundfactsapi.com/pricing
- Site index for AI assistants: https://fundfactsapi.com/llms.txt
- Informational data, not investment advice.