My Self-Invested Personal Pension (SIPP) is no stranger to growth stocks. It contains many exciting names that I’m bullish about long term, including MercadoLibre, Shopify, Wise, and Rolls-Royce.

But SpaceX would be a unique addition, as it offers a chance to invest in cutting-edge rockets, a satellite mega-constellation, space exploration, and potentially AI data centres in space. I like the sound of that.

In a filing ahead of its IPO (expected 12 June), SpaceX said it will issue shares at $135 apiece (about £100). This would value it at roughly $1.75trn.

So, should I load up on SpaceX stock?

A three-legged business

The first thing to note is that we still don’t know for sure whether the price will be $135 per share, or how much SpaceX will ultimately raise (it’s aiming for at least $75bn). Demand will ultimately decide.

But turning to the underlying business, we know SpaceX has three divisions: the rocket launch unit, Starlink satellite internet, and the AI business.

The first includes the Falcon rocket, which flew 165 times last year, making SpaceX the world’s dominant launch provider. It recently bumped up the cost of a launch to $74m (still cheaper than rivals due to its reusability). The huge next-generation Starship is also housed here.

The second, Starlink, now has over 10m subscribers and is the fastest growing telecoms business ever. What I like here is that Starlink enjoys a massive moat (nobody can match its 10,000+ satellites and the barriers to entry are enormous). And Starlink has growing subscription revenues, which are recurring and high-margin.

Finally, there’s the AI bit made up of Grok AI tools and the X social media app. While SpaceX could one day make a fortune from AI data centres in space (to be powered by solar), this is the unit I’m less convinced about.

Cash incinerator

Why? Simply because it’s burning through cash and incurring huge losses, as we can see below.

I’m not too bothered about the rocket division’s loss, as Starlink’s dominance is being cemented due to a rapid satellite launch cadence. And while huge ongoing investments are needed to develop Starship, that thing would make SpaceX’s moat even wider, if it can reliably work.

But the losses associated with Grok, AI, and X turn me off here. It means we can’t even apply a basic earnings multiple, suggesting the stock’s going to be wildly overvalued this month.

I’m sticking with this one

I have exposure to SpaceX through Scottish Mortgage Investment Trust (LSE:SMT). The FTSE 100 fund has a meaty position in the firm, which it values at around £3bn.

It could be worth even more if SpaceX achieves a $1.75trn valuation. With IPO excitement building, Scottish Mortgage stock is up 44% in the past six months.

Now, the near-term risk here is that SpaceX bombs straight after the IPO, shredding the value of the trust’s holding before it has time to crystallise profits. And that could see Scottish Mortgage sell off heavily.

Were this to happen, however, I think the stock would be worth considering. Because beyond SpaceX, the trust also has large holdings in other world-class companies like Amazon, Nvidia, ASML, Anthropic, and Stripe.

For now, I’m sticking with Scottish Mortgage for my SpaceX exposure.

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Ben McPoland owns shares of MercadoLibre, Nvidia, Scottish Mortgage, Shopify, Wise, and Rolls-Royce.