Portfolio Rebalancing: When and How to Do It in 2026

Portfolio rebalancing brings your asset allocation back to target after market movements drift it away. Done correctly, it forces systematic buy-low-sell-high behavior. Done incorrectly, it creates unnecessary tax bills.

Why rebalancing matters

Starting at 70% stocks / 30% bonds. After a bull market, stocks become 85% of the portfolio. You now have more risk than planned — not through a decision, but through drift. A correction that should drop your portfolio 20% now drops it 30%. Rebalancing prevents risk from growing unchecked.

Two rebalancing approaches

Tax-efficient rebalancing methods (in order of preference)

1. Direct new contributions: Contribute new money to underweight asset classes. No selling, no taxes. Best method when you're still contributing.
2. Rebalance inside tax-advantaged accounts: Sell and buy freely inside 401(k), IRA, HSA — no tax consequences. Save taxable account for last.
3. Dividend reinvestment to underweight assets: Direct dividends to the underweight asset class instead of the source.
4. Tax-loss harvesting combined: Sell overweight losers, use the loss to offset gains from selling other overweight positions.
5. Sell in taxable account (last resort): Triggers capital gains. Hold 1+ year for long-term rates.

The evidence on rebalancing frequency

Vanguard research found that annual rebalancing provides essentially the same risk reduction as monthly rebalancing — with significantly lower transaction costs and tax drag. For most investors: rebalancing annually (or when drift exceeds 5%) is optimal.