Everyone on Wall Street is talking about these key risks

As the chart above shows, the US equity market is twice as concentrated as it was during the peak of the dot-com bubble in 2000. Goldman Sachs wrote a note on US equity market concentration earlier this year in a longer historical perspective showing that the market has not been this concentrated since 1932. This fact alone should make every individual investor pause for a second and think about portfolio risks and diversification: Am I having too much exposure to magnificent seven, Nvidia, or AI stocks in general?

Professional investors have diversification rules and so too should individual investors

When we talk about diversification it can often be abstract for most individual investors. Concepts like mixing bonds and equities is smart and the saying "do not put all your eggs in one basket” is understandable, but can it be more concrete?

Professional investors that want to create an UCITS* fund to manage assets on behalf of individual investors are regulated by strict and concrete diversification rules. As these rules apply for professional investors they should be considered as a good yardstick for individual investors as well. Here are the two most important diversification rules in the UCITS framework that collectively are known as the "5/10/40" rule:

1. Single issuer limit: No single asset can represent more than 10% of the fund's assets.
   
   
2. Aggregate issuer limit: Holdings of more than 5% cannot in aggregate exceed 40% of the fund's assets. So an UCITS fund having 5 stocks with 9% weight would not violate the 10% rule above, but the aggregate of those 5 stocks is 45% and thus violating the aggregate limit of 40%.

These two rules are very concrete and rules that individual investors should take note of because they ensure a minimum level of diversification. Investors that do not have enough funds to have sufficient diversification across single stocks should consider what is a called a “satellite” approach. This approach is simple. You complement your portfolio of single stocks (noting the portfolio rules above) with, for example, an ETF index tracker of global equities, the MSCI World Index. By doing this you fix the diversification issue while investing in companies you like and think will do well in the future, but you avoid taking a lot of company specific risks.

More insights on diversification check out our diversification universe for inspiration and knowledge on why it is important and actions you can take.

* UCITS (Undertakings for Collective Investment in Transferable Securities) funds are highly regulated vehicles in the EU designed to ensure a high level of investor protection. Diversification rules for UCITS funds are strict to limit exposure to any single issuer or group of issuers and to spread risk effectively.

Is there a disaster waiting to happen?

Alongside the rising equity market concentration, another associated risk is building in financial markets and it is on everyone’s lips these days. It is the unusual calmness of the US equity market and a particular option strategy which is reinforcing this calmness and smoothing returns. Have we not seen this before? Yes, in 2017 and early 2018 before the big VIX blowup and sharp equity selloff in February 2018.

The S&P 500 has not experienced a single-day decline of more than 2% since 21 February 2023 and we have only had 8 trading days with a single-day decline of more than 1% since the current bull market began on 27 October 2023. This is quite extraordinary, but also something we have seen before. The subdued market volatility is like compressing gas in canister. At one point the pressure becomes too high and something cracks.

One phenomenon that is both reinforcing this calm and building potential risks in the system is a particular options strategy called the “dispersion trade”, which our options strategist Koen Hoorelbeke has written about in his recent note Smart Investor: Hidden dangers beneath the surface of a calm market. The dispersion trade is not intuitive, but fairly straightforward: participants sell broad market volatility (by shorting VIX futures) and buy volatility (long call options) on various individual stocks with potential catalysts for increased volatility like earnings, FDA approval or other company specific news. The trade works if index volatility (VIX) remains low (right now it is historically low) while the volatility of the individual stocks goes up. This trade has become extremely popular on Wall Street and it has worked well. In fact, it has worked so well that many agree that too much money is now chasing this strategy, which is always a dangerous sign.

One of the key ingredients of why this trade works is the low correlation between stocks, which is the same as high dispersion, which means that if say the technology sector has a bad trading session then another sector such as energy might have a good session. This is very low correlation ensures that the index volatility remains well behaved and drives the success of the trade. The problem is that the very low correlation environment is now at an extreme we have not observed since 2006, often a sign that something has gone too far.

At some point we get an event (it could be Nvidia missing earnings estimates, a string of bad macro figures, some geopolitical trigger, a development in the US election) that sets off a broad-based selloff in equities. Broad based means stocks move in synch, or with higher correlation - the supreme danger to the dispersion trade. This in turn might trigger a big jump in the VIX Index and then suddenly this big options trade on Wall Street must be unwound quickly. With equity market concentration as high as it is the whole unwinding might be amplified and cause havoc in equity markets. It is almost impossible to predict when things could unravel, so the only sensible thing to do is to think about diversification, so that the portfolio can weather the next jolt of equity volatility.

Below are some other related commentaries we have done on the same subject.

• QO: New extremes and a challenging opportunity
• Podcast: Will this be the end of the magnificent seven?

Previous notes on asset allocation and macro

• French election: Is this a new Meloni moment for Europe? (24 June 2024)
• US rate cut seems distant as inflation report looms (10 June 2024)
• Commodities setback, investment drought in mining, and EM elections (3 June 2024)
• The inflation conundrum and private equity party (27 May 2024)