A concentrated stock position is a single holding that makes up a large share of someone's investable net worth. There is no official threshold and no regulator publishes one. The practical question is simpler than a percentage: how much of your retirement income would depend on what happens to one company. When the answer is "most of it," what you own is a position, not a portfolio, and the two behave very differently once you stop earning a paycheck.
How People End Up With One Dominant Holding
Almost nobody chooses concentration deliberately. It accumulates, usually through one of three routes:
- Employer stock. Years of restricted stock units, an employee stock purchase plan, exercised options, or company stock inside a workplace retirement plan add up quietly, one grant at a time.
- Inherited shares. A position that was never selected, often held partly out of a sense that selling it would be disloyal to the person who left it.
- A long-held winner. A stock bought decades ago that did well enough to grow into the dominant line item without any additional purchases. The concentration is the result of success, which is what makes it awkward to address.
Each of those paths tends to produce the same tax situation: a very low cost basis relative to the current value, which means the position carries a large embedded capital gain that is only realized when shares are sold.
Why Concentration Risk Changes When Retirement Gets Close
During working years, a concentrated position that drops can be waited out. Income keeps arriving from the job, no shares have to be sold at the bottom, and time is available for a recovery that may or may not come. Retirement removes both of those cushions at once. The same compression shows up for anyone whose earning years are packed into a short window, which is often exactly how a concentrated position got built in the first place.
This is where concentration collides with sequence of returns risk, which is the danger that the order of returns, rather than the average, determines how long savings last. A retiree funding living expenses from a portfolio has to sell into whatever price exists on the day the money is needed. Selling more shares at depressed prices permanently reduces the base that participates in any later recovery. A concentrated position makes that dynamic sharper, because a single company can fall while the broad market does not, and it can stay down for reasons that have nothing to do with the economy: a failed product, a lost lawsuit, a regulatory action, a competitor. A diversified portfolio spreads that company-specific risk across many holdings. A concentrated one does not, and an individual company carries no obligation to recover at all.
Employer stock adds one more layer for anyone still working. Salary, health coverage, any pension, and the largest holding in the portfolio all depend on the same company's outcome. Those exposures are correlated by definition, and they tend to move together in exactly the scenario a retirement plan can least absorb.
Why the Tax Bill Is the Reason People Wait
The most common reason a concentrated position never gets addressed is not attachment. It is the tax bill on the way out.
Selling appreciated shares held longer than a year produces a long-term capital gain, taxed at 0%, 15%, or 20% federally depending on taxable income, per IRS Topic No. 409. For tax year 2026, Revenue Procedure 2025-32 puts the top of the 0% band at $98,900 of taxable income for joint filers and $49,450 for single filers, with the 15% band running to $613,700 and $545,500. A large one-year sale does not sit neatly in one band; it fills them from the bottom up, which is why the same total gain can be taxed very differently depending on how many calendar years it is spread across.
Two costs stack on top of that federal rate and both are frequently missed. The net investment income tax adds 3.8% on the lesser of net investment income or modified adjusted gross income above $250,000 for joint filers and $200,000 for single filers. And a large realized gain raises MAGI, which under the two-year Medicare lookback can raise Part B premiums two years later; for 2026, the first surcharge tier begins above $109,000 MAGI for single filers and $218,000 for joint filers. State income tax is separate again and varies widely, so a full picture is never federal-only.
Working in the other direction, capital losses offset capital gains first, then up to $3,000 of ordinary income per year ($1,500 married filing separately), with the remainder carried forward indefinitely (Topic No. 409). A loss banked in an earlier down year can shelter part of a later concentrated unwind. That only helps if the losses were harvested before the sale, which is the theme of this entire page.
Company stock held inside a workplace retirement plan follows a different set of rules than shares in a taxable brokerage account, and the two should not be planned as if they were the same asset. If old plan balances are part of the picture, the 401(k) rollover rules page covers how those accounts move.
What Structures Exist for Managing a Concentrated Position?
Selling everything at once is not the only mechanism that exists. Several structures are used in practice for managing concentration without an immediate full liquidation. Each is described below at an educational level only. None of these is a recommendation, none is appropriate for everyone, and every one of them carries cost, complexity, eligibility limits, and tax consequences that require professional review before anyone acts.
- Staged or scheduled selling. Selling a set portion on a defined schedule over multiple years rather than in one transaction, which spreads realized gains across several tax years and removes the temptation to time a price.
- Rule 10b5-1 trading plans (for corporate insiders). A written plan for future trades, adopted at a time when the insider is not aware of material nonpublic information and subject to the conditions in SEC Rule 10b5-1, including a mandatory cooling-off period before trading can begin. Insiders need securities counsel and their company's own policy on this one, not general web content.
- Exchange funds. Pooled vehicles in which investors contribute concentrated shares in return for an interest in a diversified pool, generally with a multi-year commitment, accredited investor eligibility requirements, and their own fee structure.
- Protective collars and other hedges. Options positions that bracket a range of outcomes, typically limiting downside and upside together for a defined period. The constructive sale rules under IRC section 1259 can treat a hedge that eliminates substantially all risk as a taxable sale, so the tax treatment here is genuinely technical.
- Charitable remainder trusts and gifts of appreciated stock. An irrevocable trust funded with shares that pays an income stream for a term or for life and leaves the remainder to charity, or an outright gift of appreciated shares to a qualifying charity. Both route charitable intent through the shares themselves rather than through cash raised by selling them.
- Direct indexing around the position. Holding a separately managed set of individual stocks built to track an index while under-weighting the concentrated holding and its sector, which also creates opportunities to harvest losses among the individual positions. The wash sale rule in IRS Publication 550 applies to any such harvesting, and it reaches 30 days before and after a sale, including purchases in a spouse's account.
What that list is really showing is that "sell it" and "keep it" are not the only two options, and that the interesting choices are structural rather than directional.
Why the Structure Has to Exist Before the Sale, Not After
This is the part that decides whether any of the above is available at all. Nearly every mechanism in that list has to be in place before the shares are sold, because the moment of sale is the moment the gain is realized and the options collapse.
- A charitable remainder trust funded after a sale receives cash that has already been taxed, which is a materially different transaction than funding it with the appreciated shares.
- A hedge is only useful while the position is still held.
- An insider cannot adopt a 10b5-1 plan while holding material nonpublic information or during a company blackout window, and the cooling-off period means the plan cannot start trading immediately after adoption.
- Loss carryforwards have to already exist to offset a gain; they cannot be created retroactively.
- Spreading gains across tax years takes years by definition. A schedule that begins the same month someone retires has no runway left.
There is also a timing problem nobody controls. Acquisitions, tender offers, lockup expirations, and forced retirement dates arrive on someone else's schedule. A plan built in advance survives that. A plan started after the event is a reaction, and reactions in this area are expensive.
What This Looks Like as an Actual Conversation
Three professionals typically share this work, and it is worth knowing which does what before any of them are hired. A financial advisor models the position against the rest of the retirement picture: how much income the household needs, how many years of spending sit outside the concentrated holding, what an unwind schedule would look like across calendar years, and where each year's realized gain would land. A CPA or enrolled agent handles the return-level consequences and the specific tax positions. For corporate insiders, securities counsel handles the trading rules. None of that is optional overhead; it is the difference between a structure that works and one that is discovered to be unavailable at the worst possible time.
The broader 2026 tax context these decisions land in, including the capital gains bands, Medicare surcharges, and the rules on charitable routing, is covered on the retirement tax planning in 2026 page. To see how a portfolio holds up against different market and spending assumptions, the retirement income stress test and the retirement savings calculator are reasonable starting points, though neither can model an individual company's risk.
PlanVault connects you with a trusted, licensed financial advisor, at no cost to you. No free report to download, no calculator held hostage for your email address, just a straight, no-obligation review of where your retirement plan actually stands.