We have some exciting news to share! The Motley Fool UK has now become an independent, UK-owned company, led by our long-serving UK management team — Mark Rogers, Chris Nials and Heather Adlington. In practical terms, it’s the same team you know, now fully focused on serving our UK readers and members.

Just as importantly, our approach remains unchanged: long-term, jargon-free, and on your side. We’ll be introducing a new name and brand over the coming weeks — we're very excited to share it with you and embark on this new chapter together!

Are index funds safe?

Are index funds safe, or are they a bubble waiting to burst?

The content of this article was relevant at the time of publishing. Circumstances change continuously and caution should therefore be exercised when relying upon any content contained within this article.

You’re reading a free article with opinions that may differ from The Motley Fool’s Premium Investing Services. Become a Motley Fool member today to get instant access to our top analyst recommendations, in-depth research, investing resources, and more. Learn More.

Index funds are often touted as being suitable for most investors. It’s easy to see the appeal of them. Hard-earned savings can be eaten away by extortionate fees of active fund managers. The usually low lump sum and monthly contribution amounts appeal to those who wish to start small and save a percentage of their regular income. And passive investors can set up a monthly direct debit and then forget about their savings until retirement. Or can they?

Warren Buffett believes in index trackers, as do many of my fellow Fool’s. However, of late, numerous people have been warning about the dangers of investing in them. I wanted to examine this side of the argument.

Michael Burry, the famed investor from The Big Short, has concerns about passive funds. In Bloomberg, he likened index investing to the subprime CDOs that were instrumental in causing the 2008 financial crisis.

According to Burry, the similarities are caused because the price setting is not being done by “fundamental security-level analysis”. His worry is that passive investors are buying each company at a fixed ratio, rather than considering the actual value of the company in the underlying index.

Although I think index investing – or holding passive funds as part of an investment portfolio – could be a great strategy, I do share some of Burry’s concerns.

The main obstacle for me is – what happens if the markets go into free-fall?

The next bubble?

I question the temperament of a passive fund-holder. An investor with their money held totally in index funds could see their wealth drop by a huge margin. They would lack the benefit of an active fund or self-managed equities, which might enable them to shift assets to other territories or classes.

What would the average passive investor do in that situation? Hold and watch the price fall further, or sell and realise their losses? I think in this situation, a market sell-off could occur. Perhaps, then, we are in the bubble that Burry describes.

Of course, no one can predict what will happen in the market going forward. But in this situation, if the bubble pops, I think the true cool-headed passive investor who continues to buy at these low price points, might be rubbing their hands together.

Spiral?

I think that the problem of passive investors rushing to the door, and causing a downward spiral, could only arise if index funds owned the majority of the market. An estimate in 2017 put the global figure of shares owned by index funds at 18%.

Index funds have their place in the market, just as actively managed funds and personal investors who pick their investments do. Ultimately, though, if an investor can set aside time to learn about investing and keep up to date with the market news, and avoid picking a few losing stocks in the index, their returns should exceed the respective market index.

T Sligo has no position in any of the shares mentioned. The Motley Fool UK has no position in any of the shares mentioned. Views expressed on the companies mentioned in this article are those of the writer and therefore may differ from the official recommendations we make in our subscription services such as Share Advisor, Hidden Winners and Pro. Here at The Motley Fool we believe that considering a diverse range of insights makes us better investors.

More on Investing Articles

A person holding onto a fan of twenty pound notes
Investing Articles

£20,000 in savings? Here’s how you could use that to earn a monthly second income

A lump sum invested in a Stocks and Shares ISA can deliver a healthy second income. But what about if…

Read more »

Investing Articles

This red-hot investment trust has delivered 16 times the return of the FTSE 100 in 2026

FTSE 100 returns have been solid in 2026. But this niche investment trust's put a pleasingly big gap between itself…

Read more »

Middle-aged white man pulling an aggrieved face while looking at a screen
Investing Articles

See what £4,993 invested in Greggs shares a mere 5 days ago is worth now… 

Greggs shares had a brilliant run yet the going has been rather sticky lately. Harvey Jones looks for signs of…

Read more »

Female student sitting at the steps and using laptop
Dividend Shares

How much do you need in Lloyds shares to make £500 in monthly passive income?

Jon Smith runs the numbers for Lloyds' shares regarding income potential, but also assesses whether the fundamental outlook for the…

Read more »

Thoughtful man using his phone while riding on a train and looking through the window
Investing Articles

This growth stock just crashed 15% in my ISA! What should l do?

Our writer is wondering what to do with this disruptive growth stock that has just slumped by double digits. Is…

Read more »

Smiling family of four enjoying breakfast at sunrise while camping
Investing Articles

Is the Diageo share price about to explode? We’ll find out on 6 May

The Diageo share price continues to struggle but Harvey Jones still believes in this beaten-down FTSE 100 stock. Will Wednesday's…

Read more »

Woman riding her old fashioned bicycle along the Beach Esplanade at Aberdeen, Scotland.
Investing Articles

State Pension of £12,548 not enough? Here’s how to aim to add another £31,352 to your retirement income

Experts reckon (and we all know) the State Pension isn’t enough to provide for a comfortable old age. But James…

Read more »

Mature people enjoying time together during road trip
Investing Articles

These FTSE 100 stocks could turn a £20k ISA investment into £541,834

These FTSE 100 stocks have provided jaw-dropping returns over the last decade. Here Royston Wild explains why they could keep…

Read more »