Rebalance when your mix drifts from its target or when your scheduled check arrives, and adjust by selling overweight assets and buying underweight ones. Rebalancing means restoring your original target mix to keep risk at the level you planned. The U.S.
Securities and Exchange Commission describes this as selling overweight holdings and adding to underweight ones to return to the intended allocation. Drift happens fast after a rally. A 60% stock and 40% bond mix can shift toward 70% stocks, a shift that leaves you with more equity risk than planned, according to the FINRA investor guide.
Table of Contents
- Why portfolios drift off target
- Should you rebalance by calendar or by trigger?
- How do you adjust with fewer taxes and trades?
- What limits keep risk and costs in balance?
Why portfolios drift off target
Stocks and bonds rarely grow at the same pace. When stocks rise faster, they take up a larger share of the portfolio. The same shift works in reverse after a bond rally or a stock decline.
That drift changes risk, not just numbers. A portfolio built for moderate swings starts to behave like a stock-heavy portfolio. The owner then faces larger losses in the next downturn without having chosen that risk.
Should you rebalance by calendar or by trigger?
Calendar rebalancing uses a fixed date. You check annually or semiannually, then reset each asset class to target, a method summarized in Vanguard research on rebalancing. It is simple and easy to maintain.
Threshold rebalancing waits for movement. You act only when an asset class moves about 5 percentage points from target, such as stocks rising from 60% to 65% or falling to 55%. Many investors combine the two: check on schedule, but trade only when drift passes the threshold.
How do you adjust with fewer taxes and trades?
Start with cash flows before selling. Direct new contributions, dividends, interest, or withdrawals toward the underweight asset, an approach Morningstar highlights for cutting trades and taxes in its tax-efficient rebalancing strategies.
This keeps more positions untouched. Sales in a taxable brokerage account can create transaction costs and capital-gains tax. Charles Schwab warns investors to weigh that tax liability and consult a tax adviser before trading, as explained in its tax-efficient investing guide.
- Send new cash to the lagging asset class.
- Reinvest dividends into the underweight fund.
- Take withdrawals from the overweight holding.
- Sell only for the remaining gap.
What limits keep risk and costs in balance?
There is no single best frequency for every portfolio. Vanguard concluded that annual or semiannual monitoring with roughly 5% thresholds balances risk control against costs for most diversified stock-bond portfolios.
Tighter controls suit funds with daily flows. Vanguard's target-date approach uses a 200-basis-point trigger and rebalances back toward 175 basis points, holding drift near 2% versus about 7% under monthly calendar checks. Pick one schedule, write down the threshold, and trade only when the rule says so.