Early backers of SpaceX are in line to share a windfall of up to $1trillion when a curb on selling their stakes in Elon Musk’s rockets-to-artificial intelligence enterprise is lifted.

In what is set to be one of the biggest payouts in stock market history, investors and insiders who bought or owned SpaceX shares before they were listed on the US stock market can cash in their holdings from this Thursday when a 180-day ‘lock-up’ expires.

They will hit the jackpot despite a dramatic slump in the share price since SpaceX went public in the biggest flotation ever.

Offered at $135 apiece, the heavily oversubscribed shares briefly topped $200 before crashing to their current low of $108, valuing SpaceX at $1.5trillion. 

But the firm was worth about $400billion in a private share sale to investors just a year ago, meaning anyone who bought then still stands to almost quadruple their money.

That sale was before the company bought artificial intelligence start-up xAI earlier this year in a deal that boosted SpaceX’s valuation to $1trillion. 

The xAI deal also minted billions for investors and rewarded them with stakes in the now-public company worth many times their initial outlay.

SpaceX shares have slumped in recent weeks as traders turn away from AI stocks and after SpaceX aborted a launch of its Starship rocket due to an engine issue.

‘SpaceX’s price since listing has been bumpier than a ride in one of its rockets re-entering the atmosphere,’ said Russ Mould, investment director at broker AJ Bell.

Unusually, SpaceX phased the release dates for early investors to sell their shares to avoid a ‘cliff-edge’ after the 180-day lock-up ended. 

Certain early investors will only get a chance to exit by early December, when billions more shares will be available to trade.

Musk, who owns the vast majority of SpaceX and briefly became the first dollar trillionaire, cannot sell his stake until June next year.

This week’s ‘lock-up’ expiry has raised fears of SpaceX shares flooding the market, depressing the share price further.

A big test will come two days earlier when the heavily loss-making company releases its first set of results since listing on the Nasdaq exchange on June 12.

These are expected to show sales of just under $7billion in the last quarter. But break-even remains years away because of the sums needed to build and run Musk’s data centres that power its AI.

SpaceX lost a staggering $4.3billion in the previous quarter on sales of $4.7billion.

The sell-off in SpaceX shares means they are close to a level that implies investors give no value to its AI business, say analysts at Morgan Stanley – only valuing its Starlink low earth orbit satellite business powering mobile phone networks.

Nevertheless, the investment bank’s analyst Adam Jonas is still a fan. 

He said: ‘We believe the current disconnect between increasingly bearish investor sentiment and largely unchanged fundamentals creates an attractive entry point in SpaceX shares.’

Jonas reckons SpaceX shares could hit $300, with half of that value coming from its AI unit.