Warren Buffett's 90/10 Rule Every Investor Must Read

What the 90/10 Rule Actually Says

In his 2013 letter to Berkshire Hathaway shareholders, Warren Buffett described the instructions in his own will: put 90% of the money into a low-cost S&P 500 index fund and 10% into short-term government bonds. That is the entire rule.

What makes it notable is who said it. The most celebrated stock picker of the last century instructed his estate not to pick stocks.

Why 90% in an Index Fund

Buffett's reasoning has two parts. First, over long periods a low-cost index fund beats the majority of professionally managed funds after fees. Second, and more importantly, it removes the need for the person managing the money to be skilled.

His famous ten year bet against a fund of hedge funds ended in 2017. The index fund returned roughly 7.1% annually. The hedge fund portfolio returned about 2.2%. Fees explained most of the gap.

Why Only 10% in Bonds

The 10% is not for returns. It exists so that during a severe equity drawdown there is money available to spend without being forced to sell shares at the bottom. It is a liquidity buffer, not an investment.

The bond allocation is not there to make money. It is there to stop you from destroying the equity allocation.

Translating It to India

The structure travels, the instruments do not. An Indian version would look like:

• 90% in a Nifty 50 or Nifty 500 index fund with a low expense ratio
• 10% in a liquid fund, short duration debt fund, or a bank fixed deposit

Two adjustments matter. Indian equity is more concentrated than the S&P 500, so a broader index like the Nifty 500 spreads risk better than the Nifty 50 alone. And Indian inflation runs higher, so the 10% sleeve should be sized against your actual monthly expenses rather than copied blindly.

Who Should Not Use It

The 90/10 split assumes a very long horizon and a holder who will not panic. It is inappropriate if:

• You need the money within five years
• You have no separate emergency fund
• A 40% paper loss would push you into selling
• You are already retired and drawing an income from the corpus

Buffett's instruction was written for a widow with a large corpus and no spending pressure. Your situation decides whether the same allocation makes sense.

The Part People Miss

The rule is not really about the 90 and the 10. It is about admitting that most people, including most professionals, do not beat a simple index over decades, and building a portfolio that does not require them to.

Frequently Asked Questions