Sitting on one big stock? How to diversify without a tax shock
When one stock is most of your net worth, you’re carrying two risks: the concentration and the tax bill. The answer is rarely a single sale — it’s a schedule.
Key takeaways
- Diversifying a low-basis position is rarely an all-at-once decision; a written, multi-year schedule is usually the better frame.
- Map your lots first — basis, holding period and tax character decide what each sale costs.
- Loss harvesting, gifts of shares, exchange funds and hedging each have a place, and each has conditions and a clock.
- Timing does much of the work: vest dates, the one-year mark, trading windows and December 31.
The short answer
Rarely all at once. Most people diversify a concentrated, low-basis position on a written, multi-year schedule: selling long-term lots in planned tranches, offsetting gains with harvested losses, giving appreciated shares instead of cash and, where suitable, using an exchange fund or a hedge. The tax doesn’t disappear, but you choose the pace and which year each gain lands in.
When to act
Years ahead
Write the diversification glidepath: how much to sell each year, which lots go first and the tax cost you’ll accept. Exchange funds and QSBS both run on multi-year clocks.
Months before a sale
If you’re an insider, set up a 10b5-1 trading plan. New plans have a cooling-off period before the first sale.
Past the one-year mark
Sell long-term lots first. Shares from an RSU vest start their holding period on the vest date.
Before December 31
Choose which tax year each tranche lands in, harvest losses to offset it, and give appreciated shares before you sell — not the proceeds after.
Two risks, one decision
Once a single stock becomes a large share of your net worth, you carry two risks at once. The first is concentration: one company’s bad year becomes your bad year. The second is the embedded gain: the lower your cost basis, the bigger the tax bill waiting for you when you sell.
Most people freeze because the choice looks binary. Sell everything and hand over a large share of the gain in one year. Or hold everything and hope. A plan replaces that with a middle path — a schedule that reduces both risks, at a pace and a tax cost you choose.
In California the stakes are higher. The state taxes capital gains as ordinary income, with no lower rate for long-term gains, so the size of each year’s gain, and the year it lands in, matter even more.
Start with a map of your lots
A position is rarely one block of stock. It’s a set of lots, each with its own purchase date, cost basis and tax character. Mapping them shows what each sale would actually cost.
- Long-term or short-term. Lots held more than a year qualify for lower federal long-term rates, though the 3.8% net investment income tax may still apply.
- Highest basis first. Selling high-basis lots buys the most diversification for the least gain.
- RSU shares. Your basis is the value at vest, so recent vests often carry little gain.
- ISO shares. Selling within two years of grant or one year of exercise turns part of the gain into ordinary income.
- Founder or early-employee stock. Check the QSBS clock before selling anything. A few more months can change the answer.
The tools, and what each one does
No single tool fits everyone. Most plans combine a few, and each comes with its own conditions.
- Staged sales. Trim the position in tranches across several tax years instead of one, keeping each year’s gain at a level you’ve chosen.
- Loss harvesting. Invest the proceeds in a direct-indexed portfolio of individual stocks. When some fall, sell them to realize losses and use those losses to offset gains from the next tranche.
- Giving shares, not cash. Appreciated shares held more than a year and given to a donor-advised fund generally avoid the capital gain on what you give and can earn a deduction at market value, within income limits. A charitable remainder trust can sell contributed shares without immediate tax at the trust level and pay you an income stream, with the remainder going to charity. Since 2026, federal rules trim the value of itemized charitable deductions for many high earners, so we model the benefit rather than assume it.
- Exchange funds. You contribute your shares to a private partnership alongside other investors’ stock and receive a diversified interest in return, generally without recognizing the gain. To keep the deferral you typically stay in about seven years, your low basis carries over, and access is limited to qualified investors.
- Hedging. A collar or similar hedge can limit the downside while you wait out a holding period or a trading window. It has to be structured carefully: some hedges are treated as a “constructive sale” that triggers the gain anyway.
An illustrative example
Consider a hypothetical engineer holding $2 million of her employer’s stock, with a cost basis of about $200,000 and most of her net worth in that one name. Selling it all this year would put the whole gain on a single federal and California return. Instead, her plan sells roughly a fifth of the position each year for five years, starting with the highest-basis long-term lots, and the first tranche is split across December and January. New RSU vests are sold as they arrive. The proceeds go into a direct-indexed portfolio whose harvested losses offset part of later tranches, and in her highest-income year she gives shares, not cash, to a donor-advised fund. The tax isn’t eliminated; it’s spread, partly offset and timed. Figures are hypothetical and for illustration only; every situation differs and no result is guaranteed.
Hypothetical and simplified, for illustration only — not a prediction or a guarantee. Real outcomes depend on your facts and on current law, which can change.
Timing does much of the work
The tools matter. The calendar matters as much. The same sale can cost very different amounts depending on when it happens.
- Stop the position growing. If you still receive RSUs, selling new shares at vest usually adds little gain, because your basis is the value on the vest date.
- Split across December and January. A tranche divided between two tax years spreads the gain over two returns.
- Wait for the one-year mark on lots that are close to it — unless the risk of holding outweighs the tax difference.
- Mind the wash-sale window. A loss is disallowed if you buy the same or a substantially identical security within 30 days before or after the sale.
- Plan around trading windows. Insiders can usually sell only in open windows or under a 10b5-1 plan, and a new plan must wait out a cooling-off period before its first sale.
- Pay the estimated tax for the quarter you sell, so a large gain doesn’t bring an underpayment penalty.
Decide the pace in advance
The hardest part of diversifying is usually not the tax. It’s deciding while the price moves. A written glidepath sets the rules before emotions do: how much to sell each year, which lots go first, what you’ll do if the price jumps or drops, and what tax cost you’ll accept in exchange for less risk.
For some holders, keeping a slice makes sense. Under current law, assets held until death generally receive a step-up in basis, and the federal estate and gift exemption is $15 million per person in 2026, indexed for inflation after that — see Estate, Legacy & Inheritance. For others, the risk of waiting outweighs the tax saved. The plan weighs both, and we coordinate it with your CPA and attorney, so every sale is a choice rather than a reaction.
Common questions
Should I just sell everything and pay the tax?
Sometimes that’s the right call — if the gain is small, the company’s risk is high or the position is a modest share of your wealth. For many large, low-basis positions, spreading sales over several years and pairing them with harvested losses or charitable gifts can lower the total tax while still cutting the risk. We model both paths so you can compare.
How long does it take to diversify a concentrated position?
There’s no standard answer. It depends on the size of the gain, your income each year, how much risk you can live with and which tools you use. Many plans run over several years, and an exchange fund is a longer commitment. The glidepath sets the pace in writing, and we revisit it as your situation and the tax law change.
Can I harvest a loss and buy the same stock back?
Not within 30 days. The wash-sale rule disallows a loss if you buy the same or a substantially identical security within 30 days before or after the sale; the loss is added to the new shares’ basis instead. Direct indexing works within the rule by replacing a sold stock with a similar, not identical, holding.
See your diversification schedule.
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Educational only. This article is general information based on current law as of September 2026, which is subject to change. It is not tax, legal or investment advice, and not a recommendation to buy or sell any security. Examples are hypothetical and illustrative, and no result is guaranteed. Exchange funds, charitable trusts and hedging strategies carry eligibility requirements, costs and risks. Please consult your CPA and attorney before acting.