Rebalancing looks simple: set a target mix, monitor your portfolio, and correct when it drifts. Emotionally, rebalancing is difficult, especially when selling top-performing investments.
This tension is particularly visible in 401(k) plans and other long-term retirement accounts. For example, a 401(k) is a retirement plan from your employer that usually lets you choose from options such as mutual funds or target-date funds (Investor.gov). Since many people must select their own investments, they also have to decide when to trim back recent winners and bring their account back to its original risk level.
Rebalancing Is a Risk-Control Process
Investor.gov explains that rebalancing means returning your portfolio to its original investment mix. As some assets grow faster than others, you can end up with an unbalanced portfolio. The main goal is to avoid overconcentration and keep risk within your chosen zone (Investor.gov).
Vanguard notes that even without action, your portfolio can shift, resulting in unintended risk exposure. Rebalancing is about risk control—not market timing or chasing returns (Vanguard).
The key point: selling a winner through rebalancing is not a negative judgment. It prevents your portfolio from becoming concentrated in a single area and helps control risk.
Why Selling Winners Feels So Hard
Investor.gov gets that this is hard. Moving money out of something that’s doing great and into something that’s lagging doesn’t feel good (Investor.gov). That’s a big reason why people put off rebalancing, even when their portfolio is clearly out of balance.
One reason it’s tough: fear of regret. If you sell something that’s been winning, what if it keeps going up after you sell? Even if selling was the right move for your plan, it’s easy to focus on the gains you missed instead of the risk you avoided.
Recent-performance bias is another hurdle. Strong performers seem more attractive, lagging assets less so. But smart investors stick to target allocations and rebalance, not chase recent winners.
A third hurdle is the discomfort of acting against momentum. Rebalancing may require cutting back on current “winners” and adding more to current “losers,” which Investor.gov describes as a way of forcing investors to buy low and sell high (Investor.gov). That discipline can feel uncomfortable precisely because it goes against the emotional pull of recent returns.
The Disposition Effect and the Winner Problem
Behavioral-finance research has long documented the tendency of investors to sell investments that have gained in value too soon (winners), while holding on to investments that have lost value for too long (losers). This pattern is called the disposition effect. In their 1985 Journal of Finance paper, Hersh Shefrin and Meir Statman explore this tendency in "The Disposition to Sell Winners Too Early and Ride Losers Too Long: Theory and Evidence" (RePEc bibliographic record). Terrance Odean later tested the disposition effect using trading records for 10,000 accounts at a large discount brokerage house, finding that investors consistently preferred to realize gains on winning investments rather than sell losing ones (Odean paper).
At first glance, rebalancing and the disposition effect may seem unrelated. Rebalancing often requires selling recent winners, while the disposition effect describes the tendency to sell winners too soon and hold losers too long. The difference lies in the motivation.
Odean found that selling winners was typically not about rebalancing or better performance. In contrast, rebalancing is a planned, risk-management action—selling to maintain target allocations, not just to take profit.
For 401(k) investors, the practical lesson is that the same sale can mean very different things depending on the process behind it. Selling part of a winning fund because it now exceeds a target allocation may be disciplined rebalancing. Selling because the investor wants the emotional satisfaction of taking a profit may be behavioral decision-making.
How Fear Can Delay Necessary Rebalancing
Fear of selling a recent winner can delay rebalancing in several ways. First, the investor may keep raising the mental threshold for action. A portfolio that is five percentage points off target may be allowed to drift to seven, then ten, because selling still feels premature.
Second, the investor may reinterpret the target allocation after the fact. A participant who originally selected a moderate allocation may begin to describe the account as more aggressive simply because stocks have risen. That can turn market drift into an accidental shift in risk tolerance.
Waiting for the perfect moment to rebalance misplaces the focus. Rebalancing restores your target allocation by trimming overgrown positions and adding to underweighted positions.
Finally, the investor may avoid looking at the allocation altogether. Fidelity cautions that monitoring investments too closely can tempt investors to trade too much, but it also recommends a balanced approach. Finally, the investor may avoid looking at the allocation. Fidelity cautions that monitoring investments too closely can tempt investors to trade too much. However, it also recommends a balanced approach. This approach keeps allocations reasonably on course while considering taxes, transaction fees, and mental bandwidth (Fidelity), including reviewing on a set schedule, rebalancing when allocations drift by a predetermined amount, or combining both methods (Fidelity). Investor.gov similarly explains that investors can rebalance based on the calendar or when the relative weight of an asset class changes by more than a percentage identified in advance (Investor.gov).
A rules-based rebalancing plan shifts the focus from feelings for current holdings to a simple question: Has my portfolio moved outside my agreed limits?
Another way to address the fear is to use contributions when possible. Investor.gov says investors who make continuous contributions can adjust their contributions to direct more money to underwriting. Another way to address the fear is to use contributions when possible. Investor.gov says investors who make regular contributions can adjust the amounts. More can go to underweighted categories until the portfolio is balanced (Investor.gov). Fidelity also notes that new contributions may let investors restore target allocations without selling positions. They do this by buying more of categories that have shrunk in percentage terms (Fidelity).iods (Investor.gov rebalancing commentary). Smaller moves may be easier for investors who understand the need to rebalance but are uncomfortable with selling a strong performer all at once.
Reframing helps: rather than say "sell the winner," say "stick to the plan." The focus is on realigning the portfolio with its intended risk level.
A Practical Checklist for 401(k) Investors
A simple checklist can make rebalancing less emotional:
· Identify the target allocation: The target should reflect goals, time horizon, and risk tolerance rather than recent performance (Investor.gov).
· Measure current allocation: Fidelity recommends comparing actual allocation with target allocation and looking for categories that are over target or under target (Fidelity).
· Use a predetermined rule: Calendar, threshold, or hybrid methods can help decide when to act before emotions take over (Fidelity).
· Consider contributions first: Ongoing contributions may help rebalance toward underweighted categories without selling current holdings (Investor.gov).
· Check plan rules and costs: Fidelity notes that rebalancing in a tax-advantaged account such as a 401(k) does not generate tax consequences, but investors should still consider fees, fund restrictions, and plan rules (Fidelity).
· Document the reason: Writing down “to return to target allocation” can help separate disciplined rebalancing from emotional profit-taking.
The Bottom Line
Rebalancing is uncomfortable because it often asks you to reduce recent winners and add to laggards. This emotional discomfort causes a delay.
Don't ignore your feelings—design a process to reduce their impact. Clear targets, preset review periods, and documenting your rationale help keep rebalancing focused on risk rather than past performance.
Source URLs
· Investor.gov, Beginners’ Guide to Asset Allocation, Diversification, and Rebalancing
· Investor.gov, Is It Time to Rebalance Your Investment Portfolio?
· Vanguard, Rebalancing Your Portfolio
· Fidelity, Rebalancing Your Portfolio
· Terrance Odean, Are Investors Reluctant to Realize Their Losses?
· RePEc, Shefrin and Statman, The Disposition to Sell Winners Too Early and Ride Losers Too Long
This material is provided for informational and educational purposes only and should not be construed as individualized investment, tax, legal, behavioral-finance, or retirement-plan advice. Rebalancing does not assure a profit, improve returns, or protect against loss in declining markets. Investing involves risk, including the possible loss of principal. Asset allocation and diversification do not ensure a profit or guarantee against loss. Rebalancing may involve transaction costs, fund restrictions, plan limitations, or tax consequences outside tax-advantaged accounts. 401(k) plan investment options, fees, automatic rebalancing features, and target date fund glide paths vary by plan and by fund. Investors should review plan documents, fund fact sheets, prospectuses, account statements, and their personal financial circumstances and consult their financial advisor, tax professional, or plan provider before making investment or rebalancing decisions.
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