How your investment mix should change with age

Asset allocation is the split between two jobs your money can do. Stocks grow your balance over time and lurch around in the short run. Bonds barely grow but hold steady and pay you a fixed return. How much of each you hold is the single biggest decision in your portfolio, bigger than which specific fund you pick. And the right mix turns on one thing: how long until you need the money.

At 23 with a paycheck and 40 years until retirement, you want mostly stocks. You have decades to ride out crashes. Near a goal, say a house in three years or retirement next year, you want more bonds, because a 30% drop right before you spend the money is a disaster you cannot wait out. That is the whole idea. Everything else is just setting the dial.

Stocks and bonds do opposite jobs

A stock is a share of a company. When the company and the market do well, your share is worth more. The U.S. stock market has returned roughly 10% a year on average over the long run, about 7% after inflation. The catch is the ride. The S&P 500 has fallen more than 30% in a single year and taken a few years to climb back. Stocks are the engine. They are also the part that keeps you up at night.

A bond is a loan you make to a government or company that pays you fixed interest and returns your money on a set date. High-quality bonds return far less than stocks over time, often in the low-to-mid single digits, but they do not crater the way stocks do. When stocks drop hard, bonds usually hold their value or fall much less, which steadies the whole portfolio. One thing to know: bond prices move opposite to interest rates, so they are not risk-free. See why bond prices fall when interest rates rise for the mechanics.

Time horizon is the deciding factor

Hold stocks for a year and you might be down 30%. Hold them for 20 years and a loss becomes very unlikely, because the good years swamp the bad ones. The longer your runway, the more crashes you can sit through without selling. That is why a 25-year-old can stomach an aggressive mix a 60-year-old cannot.

Two crashes show the recovery in real time. The S&P 500 lost about 37% in 2008. An investor who held on was back above the old peak within a few years and far ahead a decade later. In early 2020 the market dropped roughly 34% in about a month, then recovered the entire loss inside five months. If you had needed that money in March 2020, the drop was real and painful. If your timeline was 20 years out, it was a footnote. Time is the thing that turns a stock crash from a wipeout into a blip.

The starting heuristic: 110 or 120 minus your age

A common rule of thumb sets your stock percentage at 110 minus your age, or 120 minus your age if you want to be more aggressive. The rest goes to bonds. At 25, that points you to roughly 85% to 95% stocks. The rule is not precise and it is not a law. It is a sane starting point that tilts you heavily toward stocks when you are young and shifts you toward bonds as the years pass.

Here is that rule, roughly 110 to 120 minus your age, worked out at three ages and rounded to a clean number. Watch the stock share fall and the bond share rise as the goal gets closer.

At 25 you are almost all stocks, around 90%, because you have 40 years to recover from any drop. By 45 you trim toward 75% stocks, adding a real bond cushion while still keeping growth as the main job. At 65, near or at retirement, roughly 55% stocks keeps your money growing enough to last decades while bonds protect close to half the balance from a bad market year. The exact numbers vary by source. The shape is what matters: high stocks young, more bonds as the goal nears.

The shift over time is called the glide path

Moving from mostly stocks toward more bonds as you age is the glide path. Picture a plane easing down to the runway: aggressive and high early, gradually flattening as you approach the destination. You do not flip from 90% stocks to 55% overnight. You step down a little every few years so the portfolio gets more conservative right as your need for stability grows.

You can run this glide path yourself. Once a year you check your mix, compare it to your target for your age, and rebalance by selling a slice of whatever grew too big and buying what shrank. It takes 20 minutes and keeps your risk in line with your timeline. To see how your stock and bond balances fit into the bigger picture as they grow, track them in our net worth calculator, and read the investing guide for how allocation fits a full plan.

Target-date funds run the glide path for you

If managing the dial yourself sounds like a chore, a target-date fund does it automatically. You pick the fund with the year closest to your retirement, like a Target 2065 fund, and it holds a diversified mix of stock and bond funds that slowly shifts from aggressive to conservative on its own. No annual rebalancing, no math, no decisions. One fund, set for life. We cover the details in target-date funds, the one-fund retirement plan.

The trade-off is control and cost. A target-date fund uses one glide path for everyone retiring that year, which may be more or less aggressive than you want, and it can carry a slightly higher fee than building the mix from two cheap index funds yourself. For most people just starting out, the automatic version is worth it, because the biggest risk is not a slightly wrong allocation. It is doing nothing, or panic-selling in a crash. A target-date fund quietly prevents both.

How to set yours

• Pick a target stock percentage. Start with 110 or 120 minus your age. At 25 that is about 85% to 95% stocks.
• Fill it with broad funds.A total-market or S&P 500 stock fund for the stock slice, a total-bond fund for the bond slice. Two funds cover it.
• Rebalance once a year, or skip all of it and buy a target-date fund that does the rebalancing and the glide path for you.

That is the entire system. Heavy on stocks while you are young, a steady drift toward bonds as the goal approaches, checked once a year. Get the allocation roughly right and keep contributing. The exact split matters far less than staying invested through every drop along the way.

FAQ

Is the 110-minus-age rule any good?

It is a fine starting point, not a final answer. The rule gets the important thing right: more stocks when young, more bonds as you age. What it ignores is your personal situation. If you have a stable job, a long runway, and the nerve to hold through a 30% drop, you can run more aggressive, which is why many people use 120 minus age instead. If big swings make you sell at the bottom, dial it back. Use the formula to land in the right neighborhood, then adjust for how you actually behave when the market falls.

When should I start adding bonds?

Earlier than people expect, but not by much when you are young. In your 20s and 30s a small bond slice, somewhere around 0% to 15%, is plenty, and plenty of investors hold no bonds at all that early. The real shift begins as a goal moves within about 10 years. Approaching retirement, or roughly five years out from a house purchase or other big expense, you steadily add bonds so a bad market year cannot blow up your timeline. The closer the goal, the more bonds protect the money you are about to spend.

Do I need to do this if I own a target-date fund?

No. That is the entire point of a target-date fund. It holds stocks and bonds in the right mix for your age and walks the glide path down for you automatically, rebalancing as it goes. You do not pick percentages or adjust anything. If your retirement money sits in a single target-date fund matched to your retirement year, your allocation is already handled. Just keep contributing and leave it alone.

What counts as my time horizon if I have several goals?

Each goal gets its own horizon and its own allocation. Retirement money 40 years out can be almost all stocks. A house down payment three years out should be mostly cash or short-term bonds, even though both pots belong to the same young person. Do not apply one age-based number to every dollar. Match the mix to when you will spend that specific money, then let the long-term pots ride and keep the short-term pots safe.