When to sell concentrated stock is not a yes or no on the ticker. It is how many shares belong in this calendar year versus next, lot by lot.
A pile in one name is several clocks wearing one symbol. Vest income may already be on this year’s return. Older lots may be about to turn long-term. Unvested grants are not here yet and will still land. Treating “the position” as one sale is how those clocks get mixed.
The ticker is the wrong unit
“Diversify” is not a year map. “Hold because I earned it” is not a year map either.
If you would not buy the same dollar amount of this ticker today with cash, holding the whole pile is still a buy. That is a different question from whether you are allowed to sell, and from what the vest email already booked as wages.
Three lines that are not the same decision:
- Shares that just vested — ordinary income is already on the W-2 whether you sell or hold.
- Shares that vested last year — a different basis, a different holding-period clock.
- Shares that have not vested — they will add ordinary income later, often in this same calendar year.
Selling “the concentrated stock” as one pile is how people mix a short-term year with a long-term year and call it one answer.
This year versus next
Write two numbers:
- Shares to sell in this calendar year.
- Shares to leave for next year — or later, after a clock turns.
Those numbers have to sit next to wages and any vest still coming. A sale this month stacks on income already booked. State is part of the same year, not a footnote. Estimated tax in September is a year clock, not a reason to dump the pile.
Supplemental withholding on a vest is not your rate. Federal supplemental withhold is 22%, or 37% once supplemental wages from that employer pass $1 million in the year (IRS Pub. 15, 2026). The gap stays on this year’s return whether leftover shares are sold or held. Selling can still add capital gain or loss on top.
A same-day sale at vest fair value usually adds little extra tax beyond the ordinary income already booked (IRS Pub. 525). Waiting can change the character of the gain. It does not erase the vest.
Job plus the stock is two bets on one name. Unvested grants are a third. That triple exposure is a planning frame, not a rate.
Example (made-up numbers)
Example only. Not a real person and not a Lakefolio result.
Sam’s employer stock is most of what they hold.
- W-2 wages: $205,000
- Vest this month: 900 shares at $160. That is $144,000 of ordinary income already, sold or not. After share-withhold, 580 shares sit in the account. Basis $160.
- Older lot: 1,400 shares from a vest last winter, basis $128. Those lots turn long-term in a few weeks. Price now $160.
- Another vest in November, about 700 shares, not here yet.
One “should I diversify” question. Three clocks.
- Sell the whole leftover this month. Vest income is already on the year. The 580 new shares add little extra if the price is still near $160. The 1,400 older shares, if sold before the clock turns, add short-term gain of $32 a share on top of wages and the vest. November still arrives. Concentration falls. This calendar year still stacks wages, vest ordinary income, and short-term capital gain taxed at ordinary rates — not a third vest.
- Split the years. Sell 300 of the new shares this month (cash and a smaller fresh pile). Wait on the winter lot until it is long-term, then sell part of it this year or park it for January. Leave room for November. Same ticker. Different tax year. Different leftover risk.
The point is not which map is right. The point is that “sell the concentrated stock” does not pick the map. Lots, then years.
Sam’s actual wages, state, and lot dates will differ. The method does not.
What to put on paper
- List lots, basis, and clocks. Not “the position.”
- Write a this-year share number and a next-year share number.
- Put wages and remaining vests on the same page before you add another sale.
- Then decide whether this week is the place to execute the this-year number.
If the question is still “should I diversify,” you do not have a number yet.
Run the years
Load the sample or upload an equity statement and pick the years. That is the first analysis: a tax-aware, year-by-year sell plan from the lots you actually hold.
Run the sample or upload a statement
Internal links: When to sell RSUs · RSU tax if I sell this year · Lockup expiration: what to do
Lakefolio is educational software, not tax, legal, or investment advice.