Investment Portfolio: What It Is and How to Build One

An investment portfolio is the collection of all the investments you own, including stocks, bonds, cash, real estate, and other assets, typically held across one or more accounts. The mix in your portfolio is shaped by your goals, time horizon, and how much risk you’re comfortable with.

No two portfolios look exactly the same, and that’s the point. A 22-year-old investing for retirement and a 60-year-old preparing to retire next year can have very different portfolios. So will someone investing for a house down payment in 5 years versus a college fund for kids who are still in elementary school.

If you’re just starting out with investing, or trying to figure out what your portfolio should have a mix of, and how to put one together, the process is more straightforward than it sounds. This guide walks through what an investment portfolio is, what it can include, and how to build one in 4 steps, including the option to let a robo-advisor do some of the work for you.

Investment portfolio vs. asset allocation

These two terms often come up together, and they’re related but not the same. When it comes to your portfolio, think of it as a container and your asset allocation is the recipe inside it. Your portfolio is what you own. Your asset allocation is how those investments are split across different assets like stocks, bonds, and cash. The mix you choose can have a big impact on how your portfolio moves over time, including how much it might grow and how much it could swing in any given year.

You can hold investments in different account types, like a retirement account, a brokerage account, or a robo-advisor managed account, and your full portfolio is the sum of everything you own across all of them.

What’s included in an investment portfolio?

A typical investment portfolio holds a mix of assets, each of which can behave a little differently. Holding more than one can help reduce the risk that any single bad year wipes out your progress.

Stocks

When you buy a stock, you get to own a small piece of a company. If the company does well, your share can rise in value. If it struggles, your share may experience a dip. Historically, stocks have delivered the highest long-term returns of any major asset, and markets like the S&P 500 have averaged roughly 10% annual returns over the long term. While they have historically been on an upward trend, they can still experience dips.

Most beginners don’t pick individual stocks. Instead, they invest in stocks through funds, which spread your money across many companies.

ETFs and index funds. ETFs (exchange-traded funds) are like a basket of investments. One ETF can hold hundreds or thousands of stocks, giving you instant diversification. Index funds are funds that track a specific market index, like the S&P 500. ETFs and index funds typically have low fees and are one of the most popular ways for beginners to invest in stocks. Acorns Invest portfolios are also built from a diversified mix of ETFs.

Bonds

A bond is essentially a loan you make to a company or government. In return, the borrower pays you interest over a set period then returns your original investment. Bonds tend to be less risky than stocks, but also generally offer lower returns over the long term.

Common types include:

• U.S. Treasury bonds and bills, backed by the federal government and considered among the safest investments available.
• Corporate bonds, issued by companies, with higher potential yield and higher risk than Treasuries.
• Municipal bonds, issued by state or local governments, often with tax advantages.
• I bonds, which offer inflation-indexed returns and adjust every 6 months based on inflation.
   

Bonds tend to play a stabilizing role in a portfolio, smoothing out some of the bumps when stocks experience a dip.

Real estate

You can own real estate directly (a rental property, for example) or invest indirectly through REITs (real estate investment trusts) and real estate ETFs. REITs are companies that own income-producing real estate, and they trade on exchanges just like stocks.

Real estate can add diversification to a portfolio because it doesn’t always move in tandem with stocks. For most everyday investors, REITs or REIT ETFs can be a simpler entry point than buying property outright.

Cryptocurrency

Cryptocurrencies like Bitcoin and Ethereum are digital assets that trade on dedicated exchanges. Crypto is highly volatile, and prices can swing dramatically in either direction over very short periods. For that reason, most financial professionals suggest keeping any crypto allocation to a small portion of an overall portfolio, if any.

A lower-friction option for getting some crypto exposure without managing a crypto wallet is a Bitcoin ETF, which holds Bitcoin and trades like a regular ETF in a standard brokerage account.

Cash and cash equivalents

Cash and cash equivalents include savings accounts, money market funds, certificates of deposit (CDs), and short-term Treasury bills. These are the lowest-risk part of a portfolio. They won’t grow much, but they also won’t be affected as much in a market downturn. Most portfolios keep some cash on hand for stability and for any short-term goals that are coming up soon.

Example investment portfolios

Real portfolios vary widely, but most fall along a spectrum from conservative (heavier on bonds and cash) to aggressive (heavier on stocks). Here are 3 common examples to give you a feel for how the mix changes based on goals and risk tolerance.

• Conservative portfolio. Roughly 30% stocks, 60% bonds, 10% cash. Common for someone nearing or in retirement who wants to help protect what they’ve built and reduce volatility.
• Balanced portfolio. Roughly 60% stocks and 40% bonds (the classic 60/40 portfolio). A middle-of-the-road mix designed to deliver moderate growth while reducing big swings.
• Aggressive portfolio. Roughly 90% stocks, 10% bonds and cash. Often a better fit for younger investors with decades until they need the money, who can ride out short-term drops in exchange for higher long-term growth potential.
   

These are starting points, not formulas. Your actual mix should reflect your goals, age, and risk tolerance, and it’ll likely shift over time. You can see historical returns by allocation from Vanguard if you want to dive deeper into how each mix has performed in the past.

3 types of investment accounts

Your portfolio doesn’t live in one place. It’s the sum of the investments you hold across one or more accounts. The 3 main account types are retirement accounts, brokerage accounts, and robo-advisor managed accounts.

Retirement accounts. Designed specifically for long-term retirement savings, with tax advantages built in. The most common are 401(k)s (employer-sponsored) and IRAs (which you open on your own). Acorns Later offers both Traditional and Roth IRAs, with automatic Recurring Contributions. Retirement accounts have annual contribution limits and penalties for early withdrawals before age 59½.

Brokerage accounts. Flexible, taxable investment accounts with no contribution limits or withdrawal restrictions. You can buy and sell investments anytime and use the money for anything: a house down payment, a wedding, a sabbatical, or general long-term saving. You pay taxes annually on any dividends and capital gains.

Robo-advisor accounts. A type of brokerage account where a platform builds and manages your portfolio for you. You answer a few questions about your goals, time frame, and risk tolerance, and the platform recommends an appropriate portfolio, handles rebalancing, and reinvests dividends automatically. For example, Acorns Invest is a robo-advisor that invests your money into expert-built ETF portfolios and includes features like Round-Ups® (which automatically invest the spare change from your everyday purchases) and Recurring Investments.

The benefits of a diversified portfolio

A diversified portfolio spreads your investments across different assets and industries so your portfolio doesn’t rise or fall with any single investment. If one stock drops, others may grow, which reduces the overall impact on your portfolio.

This idea is the foundation of Modern Portfolio Theory, developed by economist Harry Markowitz in the 1950s and recognized with a Nobel Prize in 1990. The basic principle is that a well-diversified portfolio can be designed to maximize potential return for a given level of risk.

ETFs and index funds can make diversification easy. A single S&P 500 index ETF gives you exposure to 500 companies across every major industry. Layering in bonds, international stocks, and other assets can add another level of balance. Diversification doesn’t eliminate risk or guarantee returns, but it’s one of the most widely recommended strategies for managing risk over the long term.

How to build an investment portfolio in 4 steps

Building a portfolio comes down to 4 steps: identify your goals, assess your risk tolerance, choose your asset allocation, and rebalance over time. You can do this yourself, or you can use a robo-advisor that handles steps 3 and 4 automatically.

Step 1: Identify your financial goals

Start with what you’re investing for, because the goal shapes everything else. A retirement portfolio you won’t touch for 30 years can take on more risk than a portfolio you’re building for a down payment 5 years from now.

Write down each goal, when you’ll need the money, and roughly how much you want to have by then. A goal-by-goal approach helps you match each pot of money to the right account type and asset mix.

Step 2: Assess your risk tolerance

Risk tolerance is your comfort level with the possibility that your investments could lose value. Some people are fine seeing their portfolio drop 20% in a bad year because they know they won’t need the money for decades. Others may lose sleep over a 5% dip.

There’s no wrong answer, but your risk tolerance should shape what you invest in. A compound interest calculator can help you see how different growth assumptions play out over your time horizon, which can be a useful context when you’re deciding how much volatility you’re willing to take on.

Step 3: Determine your asset allocation

Asset allocation is how you split your portfolio across stocks, bonds, cash, and other assets. It’s usually the single biggest driver of your portfolio’s long-term performance and risk.

A general rule of thumb is the Rule of 100: subtract your age from 100 to get a rough starting point for your stock allocation. At 30, that’s 70% stocks, 30% bonds. At 60, that’s 40% stocks, 60% bonds. It’s a rough framework, and your actual mix should reflect your specific goals and risk tolerance.

For a deeper look at how to choose an allocation that fits your situation, see our full guide to asset allocation.

Step 4: Rebalance periodically

Over time, your portfolio could drift from its target mix as some investments may perform differently than others. Portfolio rebalancing brings your allocation back in line, either by selling a bit of what’s grown and buying more of what’s lagged, or by directing new contributions toward the underweight side.

Most financial experts recommend rebalancing every 6 to 12 months, or whenever your allocation drifts more than 5–10% from your target. Robo-advisors typically rebalance automatically as part of the service.

How Acorns Invest builds your portfolio for you

When you work with a robo-advisor, they can handle most of the steps for you. Acorns Invest is a brokerage account paired with a robo-advisor. When you sign up, you’ll answer a few questions about your goals and risk tolerance, then get matched with an expert-built ETF portfolio designed for that profile.

From there, Acorns handles the work of keeping your portfolio on track. Your portfolio is automatically diversified across ETFs, which hold hundreds of stocks and bonds. Dividends are reinvested. Your portfolio is rebalanced for you as your allocation drifts.

You can start investing with as little as $5, and also lean into automated tools like Real-Time Round-Ups® and Recurring Investments to invest consistently without having to think about it. If you also want to invest for retirement, Acorns Later adds a Traditional or Roth IRA to the automated approach.

Start investing with Acorns.

Frequently asked questions

What’s a good investment portfolio for a beginner?

A good investment portfolio for a beginner is usually a simple, diversified mix of low-cost index funds or ETFs across stocks, bonds, and cash, with the exact split determined by your age, goals, and risk tolerance. Many beginners can start with a robo-advisor to handle the allocations for them.

The advantage of starting with funds rather than individual stocks is built-in diversification. One ETF can give you exposure to hundreds of stocks and companies. That removes the pressure of trying to pick certain companies, which even professional investors struggle to do consistently.

How much money do I need to start an investment portfolio?

You don’t need a lot of money to start an investment portfolio. Some platforms let you start with as little as $5. Acorns Invest, for example, requires a $5 minimum to begin investing.

Fractional shares make this even more accessible. Instead of needing to buy a full share of an ETF, you can invest any dollar amount and own a small slice. Consistency over time typically matters more than the amount you start with.

What’s the difference between an investment portfolio and asset allocation?

Your investment portfolio is what you own: all your investments held together. Your asset allocation is how those investments are split across assets like stocks, bonds, and cash. You can think of your portfolio as the container and the allocation as the recipe.

Two people can have very different portfolios that share the same asset allocation, and the same investor’s portfolio can keep the same allocation over time even as specific holdings inside it change.

How often should I rebalance my investment portfolio?

Most financial experts recommend rebalancing every 6 to 12 months, or whenever your asset allocation drifts more than 5–10% from your target mix. Some robo-advisors, including Acorns, rebalance automatically as part of the service.

Rebalancing doesn’t always mean selling. You can also rebalance by directing new contributions toward the underweight side of your portfolio, which can be more tax-efficient in a taxable brokerage account.

What’s a balanced investment portfolio?

A balanced investment portfolio typically holds about 60% stocks and 40% bonds. It’s a mix designed to deliver moderate growth while reducing volatility. More aggressive portfolios lean heavier on stocks while more conservative portfolios lean heavier on bonds and cash.

While history can’t predict future results, the classic 60/40 portfolio has averaged historical returns between 8–9% annually. It’s often used as a default starting point for investors who want long-term growth but don’t want to take on too much risk compared to an all-stock portfolio.

Can I build an investment portfolio without a financial advisor?

Yes. Many beginners build their portfolios using a robo-advisor, which automates the asset allocation and rebalancing a financial advisor would handle. Robo-advisors can typically cost much less. Acorns Invest, for example, is available in all our plans, and is a common choice for both beginners and experienced investors.

Self-directed investing through a brokerage account is another option if you’d rather pick your own investments. The most important factor in either approach is starting and staying consistent, regardless of which path you choose.