SpaceX Is Worth $2 Trillion. Why Does Its Stock Swing Like a Small-Cap?

SpaceX Is Worth $2 Trillion. Why Does Its Stock Swing Like a Small-Cap?

Daragh Thomas

Thu, September 17, 2026 at 5:00 PM GMT+3 3 min read

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Elon Musk's SpaceX (NASDAQ:SPCX) has a market cap of about $2 trillion, but its stock doesn't trade like it.

Over the past 22 trading sessions, the gap between SpaceX's daily high and low averaged 4.53% of its closing price.

That compares with 4.52% for $38 billion Rocket Lab Corp. (NASDAQ:RKLB) and 1.89% for Microsoft Corp. (NASDAQ:MSFT), based on S&P Global Market Intelligence daily price data.

Three factors may help explain the gap: relatively little SpaceX stock is available to trade, investors are pricing several fast-changing businesses at once, and Musk has attracted an unusually committed retail shareholder base.

A Mega-Cap With a Small Float

SpaceX still has a relatively limited pool of stock available to trade. SpaceX has about 1.91 billion shares in its float, just 14% of its 13.57 billion shares outstanding, according to StockAnalysis.

Those shares turn over quickly. About 77 million SpaceX shares have changed hands on an average day over the past 20 sessions, equal to roughly 4% of its float. For Microsoft, the comparable figure is 0.27%.

That supply is expanding as post-IPO lockups expire. Up to 328.4 million additional SpaceX shares become eligible for sale Sept. 24, two days after the current target for Starship Flight 14.

S3 Partners estimated short interest, or bets against the stock, peaked at about 34% of SpaceX's tradable float in early August. It fell to roughly 11% within a week as shares rebounded and an Aug. 6 lockup expiration made about 912 million more shares eligible for sale.

S&P Global separately called SpaceX a "focal point for disagreement" and said it was July's largest single-stock securities-lending revenue generator, with nearly $29 billion worth of shares out on loan on average.

SpaceX Has More Than One Story

Investors are simultaneously valuing SpaceX as a reusable-rocket company, global broadband network, potential mobile carrier, frontier-AI lab, AI infrastructure provider and, further out, an orbital data-center operator.

Starship Flight 14 shows how those narratives can converge. SpaceX is targeting Sept. 22, pending regulatory approval, for Starship's first orbital flight and the deployment of 26 Starlink V3 satellites.

Traders on Polymarket give Flight 14 a 91% chance of launching by Sept. 30. Roughly $676,000 has traded across the broader Flight 14 market.

The 'Cult Stock' Factor

Steve Eisman called SpaceX a potential "retail cult stock" before its IPO and later said Musk has "believers, not investors."

Retail behavior has given that argument some backing. Vanda Research data cited by Reuters showed SpaceX recorded no day of net retail selling from its June 12 IPO through Aug. 5, including when shares fell as much as 12.9% after earnings.

SpaceX may already be worth $2 trillion, but investors are still deciding what kind of company they own. That leaves plenty of room for each new launch, AI announcement or Musk comment to move the stock like a much smaller company.

Image: Shutterstock

Read Also:Cathie Wood Says SpaceX Didn't Need an IPO—Until Data Centers in Space Came Along

This article SpaceX Is Worth $2 Trillion. Why Does Its Stock Swing Like a Small-Cap? originally appeared on Benzinga.com

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