How to Build a Diversified US Stock Portfolio Step by Step

Owning a handful of stocks you love can be exciting, but concentrated portfolios expose you to company-specific risk. Diversification spreads that risk so that a single disappointment can't derail your goals.

Step 1: Decide Your Asset Allocation

Start with the big picture: what share of your money goes to stocks, bonds and cash? This decision drives most of your portfolio's ups and downs. Longer time horizons can usually support more stocks; shorter horizons call for more bonds and cash. Our risk management guide helps you choose.

Step 2: Diversify Across Sectors

The S&P 500 is divided into 11 sectors, including Information Technology, Health Care, Financials, Consumer Discretionary, Communication Services, Industrials, Consumer Staples, Energy, Utilities, Real Estate and Materials. Each reacts differently to economic conditions. A broad index fund gives you all of them automatically; if you pick stocks, avoid concentrating in one or two. Sector ETFs can fill gaps.

Step 3: Mix Company Sizes and Styles

• Large caps: stability and global reach.
• Mid caps: a balance of growth and maturity.
• Small caps: higher growth potential, more volatility.

Also balance growth and value styles. Our market capitalization guide explains the size categories.

Step 4: Consider International Exposure

US companies earn plenty of revenue abroad, but owning some international stocks adds further diversification, since different economies lead at different times.

Step 5: Use Funds as Your Core

The easiest route to diversification is a low-cost index fund or ETF. A "core and satellite" approach — a broad fund as the core with a few individual stocks or themes around it — works well for many investors.

Step 6: Rebalance Regularly

Over time, winners grow into a bigger share of your portfolio. Rebalancing once or twice a year restores your targets. See our portfolio rebalancing guide.

Common Diversification Mistakes

• Owning many funds that hold the same large companies.
• Over-concentrating in your employer's stock.
• Confusing "many stocks" with "diversified" — 20 tech stocks are still one bet.