Since its IPO on June 12, SpaceX's stock has fallen for three consecutive days, with a cumulative decline exceeding 16%, before ending the streak with a 1% gain. Its inaugural bond offering received approximately 3.6x oversubscription, reflecting cautious market sentiment. Meanwhile, Tesla has bucked the trend with a strong performance, as the valuation arbitrage logic under the "Musk Empire merger" expectation reshapes investors' allocation strategies for "Musk-linked stocks."
"Sell SpaceX, Buy Tesla": The Math of Valuation Arbitrage
The valuation gap between SpaceX and Tesla creates a potential arbitrage opportunity:
| Metric | SpaceX | Tesla | Gap |
|---|---|---|---|
| Market Cap / Valuation | US$1.77T (IPO) | ~US$800B | 2.2x |
| Price-to-Sales Ratio | 100x+ | ~14x | 7x |
| Profitability | Net loss of US$4.94B in 2025 | Profitable | Loss vs. Profit |
| Business Maturity | Starlink cash flow + rocket launches + xAI burn | Mature auto + energy + robotics | Early-stage vs. Mature |
Analysts suggest that buying Tesla at a lower valuation may be a more cost-effective way to gain exposure to the merged "Musk Empire." The ~US$1.3 trillion "Musk premium" between SpaceX's US$2.1 trillion market cap (IPO debut) and Tesla's US$800 billion raises the question: Is this premium justified? It depends on whether xAI's AI business can achieve rapid commercialization and whether Starlink's cash flow can cover xAI's burn rate.
Masayoshi Son "Cold Water": Space Data Centers "Make No Sense"
SoftBank Chairman Masayoshi Son cast a shadow over SpaceX's "space vision" at the company's shareholder meeting. He bluntly stated that the space data center concept "makes little sense," arguing that launch costs, on-orbit maintenance, and communication latency far outweigh any energy advantages, and that the AI race will ultimately be decided by terrestrial computing power. He reaffirmed SoftBank's strategic focus on ground-based AI infrastructure, believing the next few years will be the decisive period.
This stands in direct conflict with Musk's grand narrative of becoming a "multi-planetary species." Son's skepticism highlights a core risk in SpaceX's valuation: how much of the US$1.75 trillion is "story premium" based on long-term visions like "space data centers," "lunar bases," and "Mars colonization"? If these visions are disproven or delayed, the valuation correction could be substantial.
Conclusion
SpaceX's post-IPO performance marks the capital market's first public vote on the "Musk narrative." The cumulative 16% decline suggests institutional investors are cautious about the US$1.75 trillion valuation—Starlink's cash flow is solid, but xAI's US$14 billion annual burn is a heavy burden; the "space data center" story is compelling, but Son's skepticism represents the pragmatic view.
The "sell SpaceX, buy Tesla" arbitrage logic is essentially a "de-risking" strategy—Tesla's earnings certainty, mature auto business, and Optimus robot mass-production prospects provide a more solid valuation foundation than SpaceX. If Musk does push forward with a merger between SpaceX and Tesla (a long-rumored market speculation), holding Tesla would be equivalent to gaining exposure to SpaceX at a discount. However, the risks lie in the merger timeline, regulatory hurdles, and Musk's control arrangements over both companies (he still holds over 50% voting power in SpaceX post-IPO), all of which make this arbitrage strategy highly uncertain.