Selling Stock: The Two Decisions That Carry the Cost

The Order Type Decides Your Price

A market order instructs your broker to sell at the best available price immediately. It will almost certainly execute. It says nothing about what you receive.

A limit order names a minimum price and will not fill below it. It guarantees the price and not the execution.

That is the entire trade-off, and which side of it you want depends on the security. In a heavily traded large-cap during the core session, the difference is usually pennies. In a thinly traded stock, or outside normal hours, a market order can execute somewhere you would not have chosen.

When the distinction actually bites

The SEC's guidance on extended-hours trading is explicit about the conditions: less liquidity, wider spreads, greater price volatility and less price competition. A market order sent into that environment accepts whatever the thin book offers.

The same applies during a volatility halt. Limit up-limit down bands prevent trades outside 5%, 10%, 20% or the lesser of $0.15 or 75% depending on the price tier, and the bands widen around the opening and closing auctions. A market order resting when trading pauses will fill at whatever price emerges on the reopening, which can sit well away from where the halt began.

Stop Orders Are Not Protection

A stop order becomes a market order once the stock trades at your stop price. A stop-limit order becomes a limit order instead.

The distinction matters in exactly the circumstances people set stops for. In a sharp decline, a stop order triggers and then executes at whatever the market offers, which in a fast-falling market may be far below the stop.

A stop-limit protects the price but may not execute at all, leaving you holding a position you intended to exit.

Neither is a safety net. A stop set below the market does not guarantee an exit at that level; it guarantees an attempt.

The Trade Date Governs Everything Tax

Settlement now completes one business day after execution, following the SEC's rule with a compliance date of May 28, 2024. But the date that matters for tax is the trade date, not the settlement date.

That single fact carries more financial consequence than the order type in most cases.

One year, and the cliff on either side of it

The IRS is unambiguous: hold an asset more than one year before disposing of it and the gain is long-term; hold it one year or less and it is short-term.

The gap between 37% and 15% on the same gain is not a rounding difference. On a $10,000 profit it is $2,200. An investor approaching the one-year mark has a concrete, quantifiable reason to check the purchase date before selling, and the boundary is a cliff rather than a slope: one day either side changes the entire treatment.

Losses Have Their Own Rules

Selling at a loss is not purely bad news. Capital losses offset capital gains, and beyond that the IRS permits deducting up to $3,000 of net capital losses against ordinary income each year, or $1,500 for married filing separately.

Excess losses are not forfeited. They carry forward to later years, so a large loss can shelter gains for a long time.

The wash sale rule closes the obvious loophole

Selling at a loss and immediately rebuying would let anyone harvest a deduction without changing their position. Publication 550 prevents it: if you acquire substantially identical stock or securities within 30 days before or after the sale — a 61-day window in total — the loss is not deductible in the year of sale.

The loss is deferred rather than destroyed. It is added to the cost basis of the replacement shares, so you recognize it when you eventually sell those without triggering another wash sale.

Two details catch people. The window extends backwards as well as forwards, so buying more shares shortly before selling at a loss can trigger it. And "substantially identical" requires judgement, so switching between two funds tracking the same index is not obviously safe.

Which Shares You Are Actually Selling

If you bought the same stock several times at different prices, the shares you sell are not automatically the ones you choose. Unless you specify otherwise, brokers generally default to selling the earliest-purchased lot first.

That default has consequences. The oldest shares usually have the lowest cost basis in a rising market, producing the largest taxable gain — though they are also most likely to qualify for long-term treatment. Specifying a different lot can reduce the gain, or realise a loss deliberately, but it must generally be done at the time of sale rather than reconstructed afterwards.

Selling Is Not the Same Decision as Buying

One asymmetry deserves stating. A purchase can be postponed indefinitely at no cost; there is always another opportunity. A sale of something you already hold cannot be postponed without continuing to carry the position, which is itself a decision.

This is why "I will sell when it recovers" is a weaker plan than it sounds. Holding to avoid realising a loss keeps capital committed to a company on the basis of the price you happened to pay, which the market has no knowledge of and no interest in.

The relevant question is whether you would buy the position today at today's price.

The tax rules cut across this in a specific way worth noticing. Realising a loss produces a deduction, offsetting gains and then up to $3,000 of ordinary income. Holding a losing position to avoid the discomfort of selling forfeits that benefit while keeping the exposure.

Timing Within the Session

The NYSE core session runs 9:30 a.m. to 4:00 p.m. Eastern, and conditions within it are not uniform.

Volume and volatility concentrate at both ends. The first half hour absorbs overnight news and the last carries the heaviest institutional flow, while the middle of the day is quieter with narrower ranges. For an ordinary sale, the calmer middle of the session generally offers better execution than the open.

Note also that the close is an auction rather than continuous trading, so the price recorded as the close is a single clearing price rather than the last trade. An order intended to capture the close behaves differently from one placed at 3:50 p.m.

Partial Sales and the Middle Ground

The decision is rarely binary, and treating it as such causes avoidable mistakes. A position can be reduced rather than closed.

Selling enough to recover the original investment leaves the remainder running with nothing of your own capital at risk, which changes the psychology of holding it considerably. Trimming a position that has grown to dominate a portfolio addresses concentration without requiring a view on whether the company is still a good business.

Partial sales also interact usefully with the tax rules. Splitting a large gain across two tax years can keep income below a threshold that would otherwise push the whole gain into a higher bracket, and realising part of a position in a year when you also hold losses lets the two offset each other.

What Selling Does Not Require

• A reason the market agrees with. You can sell for any reason or none; liquidity does not depend on your thesis being right.
• Selling the whole position. Partial sales are ordinary, and selling enough to recover the original stake is a common way to manage a large gain.
• Same-day cash. Proceeds settle one business day later, so the money is not immediately available for withdrawal.
• A market order. Nothing obliges you to accept whatever price exists, and in illiquid securities that acceptance is the expensive part.

The Bottom Line

Two decisions carry almost all the consequence. Choose a limit order unless the stock is highly liquid and you are trading in the core session, because the alternative accepts an unknown price. And check the purchase date before selling, because crossing one year changes the rate on the gain from as much as 37% to 15% or less.

Everything else is secondary but still useful: losses offset gains and then $3,000 of ordinary income annually with the remainder carried forward, the wash sale rule disallows a loss if you rebuy within 30 days either side, and the lot you sell is chosen at the time of sale or chosen for you.

For the session those orders land in, see trading hours; for what the spread costs on the way out, see bid and ask prices; for what happens after execution, see clearing and settlement.