A foundational guide to building your core portfolio with the right asset mix
Most investment portfolios are built from three primary instruments: stocks, bonds, and ETFs. Understanding what each one is — and what role it plays — is the foundation everything else is built on.
A stock is a share of ownership in a company. A bond is a loan you make to a government or company in exchange for interest payments. An ETF (exchange-traded fund) is a basket that holds many stocks or bonds in a single security.
Stocks rise and fall based on the company's earnings, growth prospects, and broader market sentiment. Over decades, U.S. stocks have averaged about 10% per year — but with significant year-to-year volatility, including occasional 30–50% drawdowns.
Bonds pay you a fixed interest rate (the "coupon") on a regular schedule, then return your principal at maturity. They're less volatile than stocks but offer lower long-term returns — historically about 4–5% per year for high-quality bonds.
ETFs combine the diversification of mutual funds with the tradability of stocks. Buy one share of an S&P 500 ETF and you instantly own a slice of 500 companies. Most index ETFs charge expense ratios under 0.10% — far cheaper than actively-managed funds.
Stocks: highest long-term returns, highest volatility
Bonds: lower returns, lower volatility, predictable income
ETFs: convenient, diversified, low-cost — usually the best vehicle for most investors
A common starting allocation: stocks for growth, bonds for stability, in proportions that match your time horizon
From 1928 through 2023, U.S. large-cap stocks returned about 10% per year on average, while 10-year Treasury bonds returned about 4.5%. The difference is enormous over long horizons — but bonds are much less likely to lose value in any given year.
A classic 60/40 portfolio (60% stocks, 40% bonds) has historically returned about 8% per year with substantially smaller drawdowns than 100% stocks. Younger investors typically tilt toward more stocks; people approaching retirement gradually shift toward more bonds.
Past returns are not guarantees. Bonds in particular performed poorly in 2022 when interest rates rose sharply. Diversification across both asset classes still beats picking one and hoping.
Stocks offer the highest growth potential over long horizons
Bonds provide income and stability when stocks crash
ETFs deliver instant diversification at very low cost
You can build a complete portfolio with just 2–3 ETFs
Most ETFs are tax-efficient — fewer taxable distributions than mutual funds
Stocks can lose 30–50% in a bear market
Bonds underperform when interest rates rise (as in 2022)
Individual stock picking has poor odds — even pros mostly underperform index funds
Some niche ETFs charge high fees or use complex leverage — read the prospectus
Tax treatment differs by account type and country
A simple rule of thumb: subtract your age from 110 to get your stock percentage. The rest goes in bonds. Adjust based on your risk tolerance and goals.
25 years old, retiring at 65: ~85% stocks, ~15% bonds. You have 40 years of compounding and can ride out crashes.
45 years old, retiring at 65: ~65% stocks, ~35% bonds. Still mostly growth, but starting to add ballast.
60 years old, near retirement: ~50% stocks, ~50% bonds. Stability matters more — a 40% drawdown right before retirement is hard to recover from.
Pick your stock ETF: A broad-market US ETF like VOO (S&P 500) or VTI (total market) covers most investors. Add VXUS for international diversification.
Pick your bond ETF: BND (total bond market) is the standard. Stick with high-quality investment-grade bonds — junk bonds defeat the stability purpose.
Decide your allocation: Use the age-based rule above as a starting point. Write it down — you'll want a reference during the next market crash.
Rebalance annually: Once a year, sell the winner and buy the loser to return to your target allocation. This forces you to buy low and sell high automatically.