SpaceX is already a momentum stock. It jumped again on Monday, only its second day of trading.

On Monday, shares of Elon Musk’s rocket company closed up almost 20%, at $192.50. That beat their 19% day-one gain on Friday.

The broader market helped SpaceX, too. The S&P 500 gained 1.7%, boosted by the deal to end the Iran war.

Also lending a hand to the stock: SpaceX’s underwriters exercised the overallotment option to sell an additional 83.3 million shares, raising another $11 billion. It’s more cash for the company and a sign that demand for shares is strong.

Overallotments are a typical part of IPOs that help brokers balance supply and demand for a new stock.

Musk did his part, too. In a post on X over the weekend, he said SpaceX’s revenue might be able to top $1 trillion in 2030.

Musk’s number was three times as high as a revenue forecast by Morgan Stanley and would be a 66-fold rise compared with 2025, working out to an average annual growth well north of 100%. No one ever accused Musk of having small goals.

Key to growing sales will be orbital AI data centers, which SpaceX plans to start deploying in 2028. SpaceX’s terrestrial data centers, which were owned by xAI before it was merged with SpaceX in February, are renting out computing space to Anthropic and Google for billions of dollars a month.

Musk is helping, but so is the broader market, which rallied after the U.S. and Iran said they had agreed an interim peace deal to end fighting in the Middle East.

SpaceX isn’t a member of the S&P 500 yet because newly public companies have to wait at least 12 months before being considered for inclusion in S&P Dow Jones Indices’ indexes.

It would have been the S&P 500’s second-best performer in most of Monday’s premarket, trailing only memory-chip maker Micron Technology. Hard-disk drive makers Seagate Technology and Western Digital were also up by more than 5%.

All three of those have emerged as momentum stocks this year, rising amid high trading volume, a signal to traders that more gains are ahead.

SpaceX, of course, only has one day of history, but it traded more than 500 million shares on Friday. IPOs typically trade big volumes on day one.

ARK Invest’s Cathie Wood is one investor who bought into SpaceX on Friday. Her investment management firm ARK Invest bought about 3.3 million shares across four exchange-traded funds, a daily trade notification showed.

The position was valued at $534 million as of Friday’s close. That’s small potatoes compared with founder Elon Musk’s stake. SpaceX’s IPO made him a trillionaire.

SpaceX remains an expensive stock, trading for about 33 times estimated 2027 sales and 93 times estimated 2027 earnings before interest, taxes, depreciation, and amortization, or Ebitda.