IPO Lockup Expiration: What Happens

An IPO lockup is a contractual ban on insiders selling their shares for a period after a listing — customarily around 180 days — agreed with the underwriters so a debut isn't buried under founder and venture-fund supply. While the lockup holds, the tradable float is roughly the shares sold in the offering; when it expires, the sellable share count can multiply overnight. That cliff is one of the most anticipated dates in any young stock's life — and, as this page's receipts show, one of the most misunderstood.

The mechanics, precisely

Lockups are contracts, not regulations: their length, coverage, and early-release triggers live in each deal's prospectus. Standard shape: insiders (founders, employees, pre-IPO investors) sign agreements with the underwriters not to sell for the stated window; some deals stagger releases in tranches, and underwriters can waive early. The arithmetic that makes expiry dramatic comes straight from how floats are built — the float guide measured H1 2026's IPOs floating a median of well under a third of their shares at listing, which means the locked majority often dwarfs everything trading. Expiry does not force anyone to sell; it makes selling possible, and markets spend the preceding weeks arguing about the difference.

The most famous expiry did the opposite of the script

The folk script says expiries crush stocks under insider supply. The most-watched lockup event in market history — Facebook's big November 2012 release, when hundreds of millions of shares came free — is on our tape:

SELECT
    round(toFloat64(argMaxIf(close, window_start, window_start < toDateTime('2012-11-14 00:00:00') AND (toHour(toTimeZone(window_start, 'America/New_York')) * 60 + toMinute(toTimeZone(window_start, 'America/New_York'))) BETWEEN 570 AND 959)), 2) AS prior_close,
    round(toFloat64(argMaxIf(close, window_start, window_start >= toDateTime('2012-11-14 00:00:00') AND (toHour(toTimeZone(window_start, 'America/New_York')) * 60 + toMinute(toTimeZone(window_start, 'America/New_York'))) BETWEEN 570 AND 959)), 2) AS expiry_day_close,
    round((toFloat64(argMaxIf(close, window_start, window_start >= toDateTime('2012-11-14 00:00:00') AND (toHour(toTimeZone(window_start, 'America/New_York')) * 60 + toMinute(toTimeZone(window_start, 'America/New_York'))) BETWEEN 570 AND 959))
         / toFloat64(argMaxIf(close, window_start, window_start < toDateTime('2012-11-14 00:00:00') AND (toHour(toTimeZone(window_start, 'America/New_York')) * 60 + toMinute(toTimeZone(window_start, 'America/New_York'))) BETWEEN 570 AND 959)) - 1) * 100, 1) AS expiry_day_change_pct,
    round(sumIf(toFloat64(volume), window_start >= toDateTime('2012-11-14 00:00:00')) / 1e6, 1) AS expiry_day_shares_m,
    round(sumIf(toFloat64(volume), window_start < toDateTime('2012-11-14 00:00:00')) / 1e6, 1) AS prior_day_shares_m,
    round(sumIf(toFloat64(volume), window_start >= toDateTime('2012-11-14 00:00:00'))
        / sumIf(toFloat64(volume), window_start < toDateTime('2012-11-14 00:00:00')), 1) AS volume_multiple
FROM global_markets.delayed_stocks_minute_aggs
WHERE ticker = 'FB'
  AND window_start >= toDateTime('2012-11-13 04:00:00') AND window_start < toDateTime('2012-11-15 00:00:00')

On the day roughly 800 million Facebook shares came unlocked, the stock rose 12.5% on 229.4 million shares — 3.2x the prior day's volume. The standard reading, offered as interpretation: the expiry was the most telegraphed event in the stock's young life, the fear had been sold for weeks in advance, and the date's arrival removed an uncertainty rather than adding supply — much of which insiders never sold anyway. The receipt's durable lesson: known dates get priced before they happen. The days that damage stocks are the ones nobody circled.

The live case on this site's watchlist

The next marquee expiry in our coverage universe belongs to SpaceX's June 12, 2026 listing. Applying the customary 180-day convention puts the window's end near early December 2026 — arithmetic on the receipted listing date, not a statement of the deal's actual terms, which live in its prospectus and may differ (tranches, waivers, and early releases are all common). What the tape will show, whenever it comes: whether the float actually grows (insider sales print as volume), what happens to the float-versus-outstanding gap that made the listing so top-heavy, and whether the FB pattern — priced in advance, non-event on arrival — repeats. The SK Hynix debut joins the same watchlist one month behind.

Reading any lockup date like the tape does

Three practitioner rules. The date is public from day one — it is in the prospectus, so by expiry week, everyone who wanted to sell ahead of it has had months. Watch volume, not just price: an expiry that passes on ordinary volume means the unlock was theoretical; insider supply shows up as tape. Staggered releases blunt cliffs: many modern deals unlock in tranches precisely so no single date carries the whole overhang — another reason single-date dread mostly misprices.

Lockup expiration FAQ

What is an IPO lockup period?

A contractual agreement barring company insiders from selling shares for a set period after the IPO — customarily around 180 days, with the exact terms in each deal's prospectus.

Do stocks always drop when the lockup expires?

No — the most famous large expiry on record, Facebook's November 2012 release, closed up 12.5% on 3.2x volume, receipted above. Expiries are scheduled, public dates, and markets price scheduled dates in advance.

When is the SpaceX lockup expiration?

The deal's actual terms live in its prospectus; the customary 180-day convention, applied to its June 12, 2026 listing date, points to early December 2026. Treat that as arithmetic, not a confirmed date.

Can insiders sell before the lockup expires?

Only with an underwriter waiver (which happens, and is usually disclosed), or via pre-existing trading plans where the deal's terms permit. Otherwise the contract holds until the stated date or tranche.

The receipt is a stored, versioned query over the 2012 tape — expand the SQL, or measure any expiry date's session on the Strasmore terminal.