Rebalancing

In short

I once watched a friend celebrate a technology stock that had climbed so high it crowded out every other holding in her account, and she did nothing until the fall erased most of what she thought she had gained. Rebalancing is the act of selling what has grown too large and buying what has shrunk too small, so your portfolio stays true to the percentages you chose at the start. You set a target, say sixty percent stocks and forty percent bonds, and when gains or losses push those shares five or ten points off course you trade back to the line. The work feels backward. You sell winners, buy losers. But it keeps risk steady and stops one good year from leaving you overexposed when the next year turns. You decide when to act based on what you can tolerate and what the trades will cost.

The whole of it

What it is

A neighbor once told me he let his account run for a decade without a single adjustment because everything was going up, and when I asked what he owned he said he did not really know anymore, just that it used to be balanced. Rebalancing is the discipline of returning your portfolio to the proportions you intended. You start with a plan: a certain percentage in domestic stocks, another in international, a third in bonds, perhaps a sliver in real estate or commodities. Markets move at different speeds. Stocks might double while bonds inch upward. Over time the portfolio you designed drifts into a shape you never chose. Rebalancing is the reset. You sell enough of what has grown and buy enough of what has lagged to restore the original weights. It is not about chasing performance. It is about controlling risk.

How it works

The idea rests on a truth most of us would rather ignore: what goes up usually becomes a larger danger. If stocks rise and you do nothing, stocks become a bigger portion of your account. You now have more money at risk in the same asset that just enjoyed a run. Rebalancing forces you to take some profit and move it to the part that has not run, which is often the part that is cheaper or less popular at that moment. You can rebalance on a calendar, say every six months or every December. You can rebalance by threshold, selling or buying only when an asset class wanders more than five percentage points from its target. Some people blend both rules: check quarterly, act only if a band is broken. The mechanics are simple. Suppose you want half in stocks. Stocks climb to sixty percent of your total. You sell enough shares to bring stocks back to fifty and use the proceeds to buy bonds or whatever is underweight. In a retirement account the trades trigger no tax. In a taxable account every sale can create a tax bill, so many investors rebalance by directing new contributions to the lagging slice instead of selling the leader.

The numbers, and where to find yours

There is no official rebalancing limit handed down by law. The thresholds are yours to set. Many advisors suggest acting when an asset class drifts five percentage points from its target, because smaller moves may cost more in trading or taxes than they save in risk reduction. Some use ten points for broad categories and tighter bands for volatile pieces. The key number is the target percentage you wrote down when you built the portfolio. If you never wrote one, you are guessing. Pull up your account statement and calculate what you own today as a percentage of the total. Compare that to what you meant to own. The difference is your drift. If you are using a target date fund or a managed account, the manager rebalances for you and publishes the policy in the prospectus. Read it. If you are building your own mix, you set the targets and the trigger points, and you do the arithmetic. Many brokerage websites will show your current allocation as a pie chart. Print it. Write your intended allocation beside it. The gap is your work.

A worked example

Consider a woman named Laura who starts the year with one hundred thousand dollars, sixty thousand in stock funds and forty thousand in a bond fund. Her target is sixty forty. By December stocks have returned fifteen percent and bonds have returned two percent. Her stock funds are now worth sixty nine thousand dollars. Her bond fund is worth forty thousand eight hundred dollars. Her total is one hundred nine thousand eight hundred dollars. Stocks are now sixty two point eight percent of the portfolio. Bonds are thirty seven point two percent. She has drifted two point eight points in stocks, two point eight points out of bonds. She decides her threshold is five points, so she does nothing yet. Another year passes. Stocks return another twelve percent. Bonds return three percent. Her stocks are now worth seventy seven thousand two hundred eighty dollars. Her bonds are worth forty two thousand twenty four dollars. Her total is one hundred nineteen thousand three hundred four dollars. Stocks are now sixty four point eight percent. Bonds are thirty five point two. She has drifted four point eight points. Still within her band, but close. One more year: stocks return twenty percent, bonds return one percent. Stocks are now ninety two thousand seven hundred thirty six dollars. Bonds are forty two thousand four hundred forty four dollars. Her total is one hundred thirty five thousand one hundred eighty dollars. Stocks are now sixty eight point six percent. She is eight point six points over target. She sells eleven thousand six hundred twenty eight dollars of stock and buys the same amount of bonds. Her new stock balance is eighty one thousand one hundred eight dollars, her bond balance is fifty four thousand seventy two dollars, her total unchanged at one hundred thirty five thousand one hundred eighty dollars. Stocks are back to sixty percent. Bonds are back to forty. She has rebalanced.

Where it goes wrong

I knew a man who rebalanced every Monday because he read that discipline wins, and by the end of the year he had traded himself into a tax problem that cost more than any risk he reduced. Rebalancing too often locks in small losses, racks up transaction fees if your broker charges them, and in a taxable account creates a taxable event each time you sell at a gain. Rebalancing too rarely lets risk creep beyond what you can stomach, and when the market turns you find yourself in a portfolio you would never have chosen on purpose. Some people rebalance by feel, selling what scares them after it has already fallen, which is the opposite of the plan. Others forget to check for years, then panic and reset at exactly the wrong moment. Another error is rebalancing inside silos. You own three accounts: a 401k, an IRA, a taxable brokerage account. You rebalance each one to sixty forty in isolation. But taken together your total stock exposure is seventy percent because your 401k is larger and drifted higher. You need to look at all accounts as one portfolio. If you hold assets with very different tax treatment, like municipal bonds in taxable and REITs in a retirement account, rebalancing without regard to location can waste the tax advantage. The mechanical mistake is using stale prices. You check your balance on a statement dated three weeks ago and rebalance to targets that no longer reflect today's values.

Questions to answer before you leave this page

What percentage of your total portfolio did you intend to hold in stocks when you started, and what percentage do you hold right now? How many percentage points of drift will you tolerate before you sell or buy to restore the target? Will you rebalance on a schedule, by threshold, or both, and have you written that rule in a place you will see it in six months? Do you own more than one account, and if so are you measuring drift across all of them combined or inside each one separately? If you rebalance in a taxable account by selling, have you estimated the tax on the gain, and would it be cheaper to rebalance by directing new contributions to the underweight asset instead? When did you last compare your current allocation to your written target, and if you have no written target, will you write one today?