Say you organize your closet so it's 70% hoodies and 30% sneakers by value. A year later, sneaker prices exploded and now your closet is worth 85% sneakers. Your collection has drifted from your original plan without you doing anything. Investment portfolios drift the same way — and rebalancing is how you fix it.
Why Portfolios Drift
Say you start with a portfolio that's 80% stocks and 20% bonds. If stocks have a great year and grow a lot while bonds barely move, your mix might shift to 88% stocks and 12% bonds — without you buying or selling anything.
That drift happens because different investments grow at different speeds. The problem? Your portfolio is now riskier than you originally planned, since stocks swing more than bonds. You didn't decide to take on more risk — it just happened quietly in the background.
What Rebalancing Actually Means
Rebalancing means adjusting your portfolio back to your target mix. In the example above, you'd sell some stock (or just invest new money into bonds) until you're back to that 80/20 split you originally wanted.
There are two common ways to rebalance:
- Sell high, buy low: Trim the part that grew the most, and add to the part that lagged behind.
- New money method: Instead of selling anything, just direct new deposits toward whatever is underweighted until things even out.
Most teens and young investors prefer the second method since it avoids extra taxes and fees from selling.
How Often Should You Rebalance?
There's no single magic schedule, but two common approaches are:
- Calendar-based: Check your portfolio once or twice a year, like every January and July.
- Threshold-based: Rebalance whenever an allocation drifts more than 5-10% from your target.
Rebalancing too often (like every week) just adds fees and stress for no real benefit. Remember, in a taxable account selling investments that gained value can trigger taxes (rules change yearly, so check current guidelines). A simple annual check-in is plenty for most people, especially teens just starting out.
Rebalancing Forces Good Habits
Here's the hidden superpower of rebalancing: it automatically makes you sell high and buy low, which is exactly what smart investors try to do — but it's hard emotionally. When stocks are soaring, it feels wrong to trim them. When they're down, it feels scary to buy more. Rebalancing takes the emotion out and replaces it with a simple rule.
This pairs really well with diversification: you pick a mix you're comfortable with, then rebalancing keeps that mix on track no matter what the market does.
Try It: Set a Rebalancing Reminder
Pick a target mix in the simulator — maybe 80% stocks, 20% bonds — and simulate a year where stocks jump 20%. Calculate how far your portfolio drifted and figure out exactly what you'd need to buy or sell to get back on target.
In real life, set a calendar reminder for every 6-12 months to check your actual allocation. It takes five minutes and keeps your risk level exactly where you want it.