Rebalancing is the disciplined act of selling what grew and buying what shrank to return a portfolio to its target allocation. It is mechanically simple and psychologically brutal — which is exactly why most investors skip it.

Why rebalance at all?

Over time, winners grow past their target weight and the portfolio drifts toward whatever recently performed. Unrebalanced portfolios quietly accumulate risk: the 20% tech sleeve becomes 45%, and the next tech drawdown hits like a concentrated bet you never chose to make. Rebalancing forces the one behavior that reliably sells high and buys low.

The two triggers

• Calendar: quarterly or annually. Simple, removes discretion, prevents over-trading. Annual is enough for most long-term investors.
• Threshold: rebalance when an asset class drifts more than 5 percentage points from target (a "5/25 rule" — 5 points for large sleeves, 25% relative for small ones). More responsive in volatile years.

Either works; the error is having neither and trusting instinct.

What to do with winners

Two honest options: trim back to target weight (sell high), or let a thesis-driven position run with an explicit plan — "I hold until the thesis breaks." What does not work is letting positions drift by default while telling yourself it was intentional.

Practical notes

• In taxable accounts, rebalance with new contributions first to defer capital gains.
• Rebalance across the whole portfolio, not per-account in isolation.
• After a big market move, run a full risk check — our portfolio analysis recomputes concentration and correlation so the rebalance is informed, not guesswork.

Key takeaways

• Drift accumulates risk silently; rebalancing is the correction.
• Calendar or threshold — pick one rule and automate the decision.
• Never let winners drift past target without an explicit plan.

This article is for informational purposes only and is not investment advice.