SpaceX (NASDAQ: SPCX) could attract $15.5 billion in passive buying this month as a Nasdaq-100 rebalance forces index funds to increase holdings.

JPMorgan estimates the company's index weight could rise from 1.25% to 2.25%, with changes taking effect before the September 21 open. Passive funds are expected to adjust positions at the September 18 close.

Index Weighting Dynamics

SpaceX is currently the seventh-largest company in the Nasdaq-100 by market value, yet its 1.25% weighting places it only 19th in the index. This discrepancy stems from the limited public float following its June IPO. Nasdaq rules cap the weight of companies with low float availability, excluding much of SpaceX's roughly $2 trillion valuation from the index calculation.

The gap is expected to narrow as post-IPO lockup expirations proceed. Approximately 911.5 million shares became eligible for trading on August 6, followed by another 319 million on August 20. Both releases occurred before the Nasdaq's August 31 reference date for the September rebalance.

With roughly $1.7 trillion in exposure linked to the Nasdaq-100, even minor weighting adjustments compel index-tracking funds, such as the Invesco QQQ Trust (NASDAQ: QQQ), to purchase billions of dollars in stock. JPMorgan projects the move to a 2.25% weight would generate the estimated $15.5 billion in net buying. TD Securities suggests the potential for an even larger adjustment, projecting a weight above 3.5%.

Market Reaction and Supply Risks

Forced buying does not guarantee price appreciation. When SpaceX joined the Nasdaq-100 in July, JPMorgan estimated $4.3 billion in passive buying, yet the stock fell more than 6% on its first day in the index. Traders often position ahead of known changes and sell into passive fund demand.

Supply pressures remain significant. More than 1 billion additional shares are eligible for trading by the end of October, with roughly 1.3 billion more expected after third-quarter earnings, according to Bloomberg.

What the Numbers Show

The divergence between SpaceX's market rank and its index weighting highlights the structural impact of float restrictions. Despite being the seventh-largest company by value, its index influence is capped at the 19th position due to low tradable supply. The upcoming rebalance directly addresses this disconnect by allowing the index weight to reflect the expanded public float post-lockup expiry.

Future Catalysts

Prediction markets show divided sentiment on SpaceX's valuation. On Polymarket, the $1.75 trillion to $2 trillion range leads at 29%, narrowly ahead of $2.25 trillion or more at 28%. The $2 trillion to $2.25 trillion range sits at 24%.

Nasdaq's methodology allows low-float companies to be added "in multiple tranches over time" as shares become available. With billions more shares due to exit lockups, subsequent rebalances could further lift SpaceX's index weighting and trigger additional passive buying.

Elon Musk stated that establishing a lasting presence on the Moon and Mars requires moving unprecedented amounts of mass into space. He identified Space Exploration Technologies Corp.’s (NASDAQ: SPCX) Starship as the critical transport system to achieve this scale.

Payload Scale And Launch Cadence

Musk wrote on X on September 6, 2026, that extending consciousness to these destinations takes significant mass. This comment responded to an estimate citing more than 22,000 metric tons of usable payload placed in space since 1957. Musk referenced his August target of achieving 30-plus Starship launches per day by 2030. At a rate of 100 tons per launch, this cadence would equate to approximately 3,000 tons of payload daily.

SpaceX has not yet demonstrated launch rates close to this target. The company’s prospectus states that Starship V3 is designed to carry 100 metric tons to orbit in a fully reusable configuration. Future generations, potentially as early as Starship V4, could reach 200 metric tons. Orbital refueling is also cited as a method to extend cargo capacity beyond Earth orbit.

Development Milestones And Costs

Musk has adjusted his cadence ambitions over time. In February 2026, he suggested Starship could eventually launch every hour. By August, he set the specific 2030 target of 30-plus launches per day. To support thousands of flights annually, Musk has backed the development of new spaceports.

Starship development has cost SpaceX more than $15 billion. The vehicle recently completed Flight 13 in July, which briefly deployed 20 Starlink V3 satellites into suborbital space. Full reusability remains central to the business case, with SpaceX stating that both Starship and Super Heavy are designed to return and fly again without refurbishment.

What The Numbers Show

The gap between current capabilities and stated targets is substantial. With cumulative historical launch mass at 22,000 metric tons since 1957, the proposed 2030 cadence of 3,000 tons per day represents a theoretical acceleration in payload delivery orders of magnitude higher than all previous human spaceflight activity combined.