PORTFOLIO COMPARISON / ONE VARIABLE

Buffett 90/10 Portfolio Backtest

Backtest a transparent Buffett 90/10 ETF proxy: 90% S&P 500 exposure and 10% short-term Treasuries, compared with a conventional 60/40 allocation.

Warren Buffett shareholder-letter allocationFrequently cited simple allocation90% S&P 500 / 10% short TreasuriesLed its reference in this test

HISTORICAL BACKTEST RESULT

60% VOO / 40% SHY vs 90% VOO / 10% SHY

60% VOO / 40% SHY 90% VOO / 10% SHY
2020-06-02 → 2026-07-31 · 1542 common sessions
60% VOO / 40% SHY$17,1559.2% annualized · -17.3% max drawdown
90% VOO / 10% SHY$22,30913.9% annualized · -23.4% max drawdown

Historical calculation from cached Marketstack EOD data. Annual rebalancing, $10,000 initial value, nominal USD before fees and taxes. The disclosed portfolio definitions—not an AI model—produce the result.

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WHAT TO COMPARE

Read the trade-off as a system.

  1. 01Ending value
  2. 02Maximum drawdown
  3. 03Annualized return
  4. 04Recovery path

WHEN TO LOOK

Locate where the difference appeared.

First common ETF observation onwardEquity drawdownsRate shocksRecent market leadership

A useful comparison shows whether an advantage was broad or created by one unusually favorable period. Review the portfolio backtest methodology to understand how the same rules are applied across a shared data window.

PORTFOLIO RULE / DISCLOSED IMPLEMENTATION

Transparent 90/10 ETF proxy

The commonly cited 90/10 instruction came from Warren Buffett’s 2013 shareholder letter. This page discloses the liquid ETF proxy and every implementation choice.

VOOVanguard S&P 500 ETFVanguard S&P 500 ETFUS large-cap equity ETFTracks the S&P 500 through a low-cost index ETF.90%S&P 500 index ETF
SHYiShares 1–3 Year Treasury Bond ETFiShares 1–3 Year Treasury Bond ETFShort-term Treasury ETFHolds short-duration US Treasury bonds.10%Short-term Treasury ETF

REBALANCINGAnnual rebalancing to 90% equities and 10% short-term Treasuries.

DATA WINDOWThe calculation uses the first shared Marketstack EOD date for VOO and SHY. It is an ETF implementation, not an index reconstruction.