Actually, Buffett does not invest in the S&P, and he's not diversified. I think what he meant was that small investors should not be trying to do what he does (picking stocks), and should just buy the S&P.
I didn't say Buffett is invested in the SP500.
Buffett famously describes diversification as "protection against ignorance," for investors who truly understand business. For the other 95% of investors, which also means the pros, he recommends the SP500.
I based my model
loosely on 3 Buffet’s rules but adapted it to funds:
Rule No. 1: Never Lose Money.
Rule No. 2: Never Forget Rule No. 1 and
Rule 3: Diversification is a protection against ignorance. I added a
fourth rule: momentum.
Rule 5 is based on experience.
My generic system looks for the best 5 wide range funds with good risk-adjusted performance, keeps changing them using momentum, and each fund must perform well. You do that 2-3 times annually. The idea is to be mostly in the right category (
never diversify) + achieve better risk-adjusted performance by looking at performance first and then selecting the best SD + Sharpe ratio funds.
In the last 10+ years, I modified it to mostly 2-3 bond OEFs and added timing for in/out of the market.
Diversification, while often touted as the key to stability, can lead to
mediocre performance when applied across several asset categories. For instance, when U.S. large-cap stocks (US LC) perform well, other categories like emerging markets (EM), international, and value stocks often lag—just look at the periods from
1995–2000 and
2010–2025. The opposite happened during 2000-10.