Is It Normal to Not Understand What Rebalancing a Portfolio Means?
“Just make sure you’re rebalancing” is one of those pieces of advice that gets repeated everywhere without ever slowing down to explain what it actually means in practice. If it never quite clicked, that’s a very common gap, not a sign of being behind.
At a glance
Rebalancing means periodically adjusting a portfolio’s holdings back toward its original target mix, such as a chosen split between stocks and bonds, after market movements have shifted that mix away from the plan. It’s not about picking new investments or reacting to news; it’s a maintenance step that keeps a portfolio’s risk level roughly where it was originally intended to be.
Why a portfolio drifts on its own
Different types of investments grow at different rates over time, which means a portfolio that started at a specific target mix won’t stay there without intervention. If stocks perform well over a stretch of time, they can grow to represent a larger share of the total portfolio than originally intended, quietly increasing the overall risk level without anyone making an active decision to take on more risk. Rebalancing is the process of noticing that drift and trimming the overgrown portion while adding to the underweighted one, restoring the original balance.
A simplified illustration
Say a hypothetical portfolio starts at a 70/30 split between stocks and bonds. After a strong run in stock markets, that same portfolio might drift to something like 80/20, without any deposits or withdrawals happening at all, purely from stocks growing faster than bonds. Rebalancing in that case would mean selling a portion of the stock holdings and using it to buy bonds, bringing the mix back toward 70/30. The numbers here are illustrative only, not a suggestion for what any actual portfolio should look like.
The different ways rebalancing gets done
There are a few general approaches people and fund managers use:
- Calendar-based rebalancing. Reviewing and adjusting the portfolio on a fixed schedule, such as once a year, regardless of how far it’s drifted.
- Threshold-based rebalancing. Adjusting only when a portfolio drifts beyond a set percentage away from its target mix, regardless of how much time has passed.
- Automatic rebalancing. Many retirement accounts and target-date funds handle this process automatically in the background, without the account holder needing to take any action, which is one reason putting money into a Roth IRA doesn’t automatically mean someone has to manage rebalancing themselves.
Why it matters even though it sounds minor
Skipping rebalancing doesn’t cause immediate harm, but over years it can leave a portfolio meaningfully riskier, or more conservative, than originally intended, simply through the compounding effect of uneven growth across asset types. This is one reason the concept comes up so often alongside broader conversations about why index funds get recommended so frequently and how long-term investing differs from more reactive trading: rebalancing is a structural habit, not a market-timing decision.
What to weigh
Not understanding rebalancing at first is extremely common, since it’s rarely explained clearly even in material aimed at beginners. The core idea is simple once it’s laid out: a portfolio’s mix drifts over time due to uneven growth, and rebalancing is the periodic act of nudging it back toward the original plan. Many retirement and brokerage accounts offer automatic rebalancing as a feature, which is worth checking before assuming it needs to be done manually.