Deciding when to rebalance is just as important as knowing how to do it. If you rebalance too often, you may eat away at your returns through fees and taxes. If you wait too long, your portfolio may drift so far that your risk level becomes unrecognizable. Investors generally use three primary "triggers" to decide it is time to act: calendar-based, percentage-based, or a hybrid of both .

Calendar Rebalancing: The Simple Schedule

Calendar rebalancing is the most straightforward approach, making it ideal for beginners. With this method, you pick a specific date or frequency—such as once a quarter or once a year—to review your portfolio and make adjustments .

Annual Review: Many long-term investors find that rebalancing once a year is sufficient . This frequency is often enough to catch significant drift without incurring excessive costs.
Quarterly Review: Some investors prefer a more "hands-on" approach and check every three months. This can be useful in highly volatile markets but requires more time and potentially more transaction fees .
The Advantage: It is easy to remember and requires very little monitoring in between the set dates. It prevents you from obsessing over daily market moves .
The Disadvantage: The market doesn't follow a calendar. A massive market shift could happen in February, but if your rebalance date isn't until December, you might be exposed to high risk for months .

Percentage-of-Portfolio Rebalancing: The Tolerance Band

Also known as "threshold" or "corridor" rebalancing, this method ignores the calendar and focuses entirely on how much your assets have moved . You set a "tolerance band" (usually around 5%) for each asset class. If an asset moves outside that band, you rebalance .

How the 5% Rule Works

Imagine your target is 60% stocks and 40% bonds. You decide on a 5% tolerance band.

Upper Limit: If stocks grow to 65% of your portfolio, you sell the extra 5% and buy bonds.
Lower Limit: If stocks drop to 55% of your portfolio, you sell bonds and buy more stocks to get back to 60%.

Asset Class	Target Weight	Tolerance Band (+/- 5%)	Rebalance Trigger
Stocks	60%	55% to 65%	Below 55% or Above 65%
Bonds	40%	35% to 45%	Below 35% or Above 45%

This method is highly responsive to market conditions. It ensures that you are always "buying the dip" or "trimming the top" exactly when it happens . However, it requires you to monitor your portfolio more frequently, which can be stressful for some investors .

Hybrid Rebalancing: The Best of Both Worlds

The hybrid approach combines the calendar and the threshold methods. You might check your portfolio on a set schedule (e.g., every six months), but you only execute a trade if an asset has drifted by more than a certain percentage (e.g., 5%) . This prevents you from making tiny, expensive trades for a 1% drift while ensuring you don't ignore a major 10% drift just because it's not "rebalancing day" yet.

Constant Proportion Portfolio Insurance (CPPI): The Advanced Trigger

For investors who want to protect a specific "floor" of wealth—perhaps for a child's tuition or a house down payment—the CPPI strategy offers a more mathematical trigger . This strategy assumes that as your wealth increases, your ability to take risks also increases.

The formula for CPPI is:
$ Stock Investment = M × (Total Assets - Floor)

The Floor: The minimum amount of money you are unwilling to lose (e.g., $150,000 for tuition).
The Cushion: The difference between your current total assets and that floor.
The Multiplier (M): A number representing your risk tolerance (usually between 3 and 6) .

As the market goes up, your "cushion" grows, and the formula tells you to move more money into stocks. If the market crashes and your total assets approach the "floor," the formula forces you to move everything into safe assets like cash or Treasuries to protect that minimum balance . While powerful, CPPI can lead to high turnover (lots of trading) and might "lock you out" of the market if you hit your floor during a temporary dip .

Step-by-Step Guide to Your First Rebalance

Identify Current Allocation: Calculate the current percentage of your portfolio in US stocks, international stocks, bonds, and cash .
Compare to Target: Look at your original plan. Which categories are "overweight" (too big) and which are "underweight" (too small)?
Calculate the Trade: Determine exactly how many dollars need to move from the overweight category to the underweight one .
Execute: Sell the winners and buy the laggards. Remember, you may need to sell first to generate the cash for the buy order .

Rebalancing Trigger Comparison Table

Strategy	Frequency	Effort Level	Best For...
Calendar	Fixed (e.g., Annually)	Low	Beginners who want a "set it and forget it" feel.
Threshold	As needed (based on drift)	High	Investors who want tight control over risk.
Hybrid	Scheduled check, conditional trade	Medium	Most balanced investors.
CPPI	Continuous/Frequent	Very High	Protecting a specific minimum dollar amount.