ONGOING PORTFOLIO MANAGEMENT
Rebalancing a portfolio
The market moves your mix whether you touch anything or not. The question is what to do about it, and how often to even look.
What “out of balance” actually means
A target mix — say 70% stocks, 30% bonds — doesn't hold still on its own. If stocks grow faster than bonds over a year or two, that same portfolio can quietly drift to 78/22 without a single trade being made. Nothing went wrong; growth just doesn't happen at the same rate across every holding. Rebalancing is simply the act of nudging the mix back toward the original target.
One holding, no drift
Everything above applies to a portfolio built from more than one holding — a stock fund and a bond fund, for example — where each piece can grow at a different pace and pull the mix away from its target. A single multi-asset (sometimes called “all-in-one” or “asset-allocation”) ETF sidesteps the question entirely: the fund itself holds stocks and bonds together and adjusts the mix internally, so there's no drift between separate holdings for an investor to notice or correct.
For anyone still holding just the one fund from “Starting simple: one broad-market ETF,” this is one of the quieter benefits of that starting point — rebalancing isn't a task that's been made easy, it's a task that doesn't exist. Nothing here applies until a portfolio grows a second holding alongside it.
Two ways to bring it back
When to actually look
There are two common ways people decide it's time to check: on a calendar (every six months, or quarterly at the most frequent) or on a threshold — checking whenever a holding drifts more than a set amount from its target, 5 percentage points being a common example.
Checking more often than quarterly doesn't make a portfolio perform better — for most long-term, buy-and-hold approaches it mostly just adds noise, and more chances to second-guess a plan that was fine as it was.
The look-and-tinker trap
The look-and-tinker trap
When the market swings, checking a portfolio can create a pull to do something — trim what's up, add to what's down, or shift the mix outside a scheduled review. That instinct is normal, but it's usually the wrong prompt to act on: reacting to short-term moves outside a planned check tends to cost more in mistimed trades than it saves.
Between scheduled reviews, not touching the portfolio isn't neglect — it's usually the plan working as intended.
A closer look at why watching a portfolio creates this pull is covered in “Managing the urge to act.”
This is also why a scheduled check matters even in years with no new contributions at all — the market can do the drifting on its own, with no deposits involved.