Using S&P 500 Valuation as a Guide for Cash Allocation

Max Teh
6 hours ago
3 min read

Disclaimer: This communication is provided for information purposes only and is not intended as a recommendation or a solicitation to buy, sell or hold any investment product. Readers are solely responsible for their own investment decisions.

Most investing discussions focus on what stocks to buy. Far fewer talk about how much cash to hold. Yet this decision can meaningfully impact both long-term returns and how one navigates drawdowns.

Over time, I’ve found it helpful to think about cash allocation through the lens of market valuation. One simple reference point I use is the S&P 500’s price-to-earnings (P/E) ratio.

Why Valuation Matters

Historically, when the S&P 500’s P/E approaches ~28x, the market tends to enter a more stretched zone. At these levels:

Expectations are elevated
Forward returns may become more compressed
Downside risk becomes more sensitive to negative catalysts

Importantly, high valuations do not directly cause corrections. However, they tend to make markets more fragile, where unexpected events can lead to sharper drawdowns.

Historical Context

We’ve seen this dynamic play out across different periods:

Dot-com bubble (2000):Valuations moved well beyond 28x, followed by a drawdown of more than 50% over the subsequent years.
2020–2022 period:P/E expanded into the mid-to-high 20s. This was followed by a sharp drawdown during COVID, and another ~25% decline in 2022 as liquidity tightened.
February 2025:Valuations again reached ~28x, after which the market experienced a meaningful correction in the months that followed.
As of today (14Apr26), the S&P 500 is trading at approximately 29.5x, placing it within historically elevated levels.

A Practical Approach to Cash Allocation

Rather than trying to predict when corrections will happen, I find it more useful to adjust positioning gradually as valuations become more stretched.

One approach that has worked for me is to maintain:

~20–25% of the portfolio in cash and cash equivalents when valuations are elevated

This allows:

Continued participation in market upside
Flexibility to deploy capital when valuations become more attractive

What Counts as Cash & Cash Equivalents?

In this context, cash and cash equivalents refer to assets that are:

Liquid
Relatively stable in value
Still generating some yield

Examples include:

High-yield savings accounts
Short-term Treasury bills
T-bill ETFs (currently yielding ≥4%)

More volatile income-generating assets such as REITs or high dividend stocks are not included, as their prices can fluctuate meaningfully during periods of market stress.

Why Not Hold More Cash?

While increasing cash can help manage risk, I generally avoid going significantly above ~25%.

At higher levels, it starts to resemble an attempt to time the market. This is difficult to execute consistently and can come at the expense of long-term compounding if one remains overly defensive for extended periods.

Instead, I view cash as:

A buffer for optionality, not a directional bet on markets

A Simple Portfolio Guardrail

This ~25% threshold also aligns with a broader rule I apply in portfolio construction:

No single position typically exceeds ~25% of the portfolio

This applies to both individual stocks and cash holdings. It helps maintain diversification while keeping risk exposure balanced.

Final Thoughts

This framework reflects my own context as a long-term investor with a multi-decade horizon. Different approaches may be more appropriate depending on one’s investment goals, time horizon, and risk tolerance.

Ultimately, investing is not just about what we choose to buy. It is also about what we choose not to deploy yet.

Having some dry powder can make a meaningful difference when opportunities emerge, especially when markets move from stretched valuations back toward more reasonable levels. Portfolio Cash Allocation Strategy