What Is AUM?

Assets under management, or AUM, is how much money is in a fund.

• It also refers to how much money a firm manages in general.

When you're researching an ETF, you need to know the fund's AUM. What you're really asking is: how much money is this fund moving around?

This information has to be provided in the prospectus. Every ETF is legally required by the SEC to make this information public.

Passive investors especially need to pay attention to the assets under management of a particular fund, as well as the manager itself.

This helps them to determine if the fund is a good investment for them or if it’s a bit too risky.

Let’s break down assets under management - why it matters to ETFs, how to find it, and a list of the biggest asset managers right now.

AUM is just one way that investors evaluate an investment.

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Why AUM Matters When You Invest in ETFs

AUM isn't just a random number. It tells you something important about risk.

The higher the AUMis, typically = lower the risk for that ETF.

Why? Because more money moving through an ETF means it's liquid. You should be able to find a buyer if you want to sell your shares.

Now for the reality: Just because an ETF or mutual fund has billions in it, doesn’t necessarily mean it’s lower risk.

This is just one way that investors can evaluate an ETF - less could mean it’s a niche ETF and may have high growth potential.

You’ll still need to dig deeper into the asset managers themselves to determine if an ETF is right for you.

Asset managers with proven track records, transparent web pages for their ETFs, and large assets under management build trust through that reputation.

The Big Asset Managers

BlackRock, Vanguard, and State Street - these three asset managers manage roughly 75% of the funds in ETFs as of 2025.

These massive asset managers put time and effort into their funds. They want to take care of them. 

Otherwise, why would someone invest?

More importantly, they're backed by a lot of money. We're talking about trillions of dollars in assets under management for the ones listed here.

Here's a look at the biggest asset managers by total AUM:

When you're looking at ETFs, you want to familiarize yourself with the giants who are doing this well.

And like most things in finance - money is important.

How to Use the CDAA Method to Check AUM

The CDAA method is how our analysts research and evaluate ETFs. It stands for:

• Companies - What kind of companies does this fund invest in?
• Dollars - What's the fund's AUM?
• Asset Allocation - What are the top holdings in this fund?

Let's look at how the "Dollars" part - the AUM - works in practice.

Example 1: SPY (S&P 500 Tracker)

SPY has $586 billion in assets under management and 503 holdings as of Q2 2025.

The risk here is low. 

You've got a ton of money in this ETF. You should be able to find a buyer if you wanted to sell your shares.

You've got the backing of State Street as well, one of the largest asset managers in the entire world. 

It's an index that's tracking the S&P 500, so it moves in line with that index.

This isn't going to be a super risky ETF.

Example 2: DIA (Dow Jones Tracker)

The DIA has $36 billion dollars in assets under management and 30 holdings.

That's pretty low risk to investors, but not no risk. There are risks to all types of investing, whether you're passively investing or actively investing.

Example 3: VIS (Vanguard Industrials - Industry Tracker)

This fund has $6 billion in assets under management and 387 holdings as of Q2 2025.

The risk is medium for this one.

There's $6 billion, which is pretty good. 

That's pretty high, but it's not really high. It's not $36 billion high compared to the DIA index. It's a little bit lower, so you have to take that into account.

This is medium risk. You may have a harder time selling shares because there's not a lot of capital flowing through this ETF compared to the bigger index trackers.

Example 4: EATZ Restaurant ETF (Niche Tracker)

This fund from AdvisorShares has $3.3 million in assets under management and 23 holdings.

The risk here is on the higher side.

Look at the comparison of the three ETFs we've looked at:

• One has $36 billion in assets under management.
• Another has $6 billion.
• This one has under $4 million.

That's $4 million broken down into 23 different companies. There's not a whole lot here.

That means you may have trouble selling your shares because it may be thinly traded.

There's not a lot of activity, and it could have less liquidity.

Low Risk vs. High Risk: What AUM Tells You

Let's look at SPY again - a low risk ETF.

You're investing with State Street, one of the largest asset managers in the world. 

It has a high number of assets under management and a sensible number of holdings. 

It tracks the S&P 500, which is the largest 500 public companies listed in the U.S. by market cap.

But on the other hand, there are ETFs on the higher risk side.

An asset manager like SonicShares is not as established. It has a low number of assets under management and very high or very low holdings.

This ultimately makes its ETFs less liquid. The funds may not be as diversified because of their narrow scope on niche assets.

Different Types of ETFs Have Different AUM Levels

There are different types of ETFs, and they each come with different AUM expectations:

Index trackers like VOO, SPY, and DIA track an index. You're not beating the market here - you're roughly matching it. 

These usually have the highest AUM.

Industry trackers follow a specific industry like public companies in the pharmaceutical industry or the cybersecurity industry. 

These have medium AUM levels.

Niche ETFs follow not only an industry but a very particular part - like artificial sugar companies in the food industry, or only automakers from one country like China. 

These have the lowest AUM.

Each one comes with its own risks and advantages.

Being able to analyze an ETF is key for you to become a successful passive investor.

The Bottom Line

Assets under management tell you how much money is in a fund. It's a key part of the CDAA method our analysts use to research ETFs.

Higher AUM generally means lower risk because the fund is more liquid. Lower AUM usually means higher risk because you may have trouble selling your shares.

The big three asset managers - BlackRock, Vanguard, and State Street - control trillions in AUM. They make up over half the ETF industry.

When you're researching ETFs, always check the AUM alongside the number of holdings and what companies the fund invests in. 

These three pieces of information help you understand if an ETF fits your investment strategy and risk tolerance.

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