Seraphim Space Investment Trust (LSE:SSIT) isn’t a well-known UK stock today. But according to data from AJ Bell, it was the most bought share on the FTSE 250 investment platform in the past week.

The fact that’s it’s up 809% since July 2023 clearly isn’t deterring these investors. For the record, that’s better than Nvidia (430%) and Rolls-Royce (670%) over this time frame.

There aren’t many UK shares — big or small — that can hold a candle to that type of performance. Let’s take a closer look at this surging stock to see what has got investors so excited.

Does it own any SpaceX shares?

As might be obvious, this is an investment trust focused on the space sector. It became the world’s first listed SpaceTech fund upon going public in 2021.

Seraphim Space Investment Trust targets early and growth stage SpaceTech companies, that have the potential to dominate globally and help tackle humanity’s most pressing challenges like climate change, communications, mobility and global security.
Seraphim Space.

Now, the way this £891m fund has performed, you’d be forgiven for thinking that it has a stake in SpaceX. Elon Musk’s rocket pioneer is gearing up for a potentially record-breaking stock market debut in a few weeks’ time.

However, it doesn’t own any SpaceX. Instead, it has chunky stakes in ICEYE (a radar satellite firm specialising in Earth observation), ALL.SPACE (satellite communication terminals), D-Orbit (space logistics), and HawkEye 360 (satellite intelligence).

ICEYE, the largest holding, is heavily integrated into the European defence and intelligence sector. Via a joint venture with defence giant Rheinmetall, it’s supplying reconnaissance data to the German Armed Forces.

But ICEYE also recently partnered with the Jane Goodall Institute to provide near real-time detection of illegal logging and mining in the Congo Basin and Tanzania.

Meanwhile, ALL.SPACE is being acquired by York Space Systems for $355m. Given this firm accounted for 15.9% of Seraphim’s net asset value (NAV), the trust should be getting a nice little cash boost soon.

Finally, HawkEye 360 is preparing for an IPO at a valuation of about $2.84bn.

Is this surging stock still worth a look?

As we can see then, the portfolio has been performing well. And the shares could do even better in the months ahead with the SpaceX IPO coming up.

A successful [SpaceX] listing could act as a bellwether for large technology and space-related IPOs, lifting broader investor appetite for the sector.
Seraphim Space.

I’ve been bullish on this trust for quite a while now (I first highlighted it when it was a 29p penny stock in July 2023). But the NAV has only gone from £222m at the end of 2022 to £337.5m in December 2025. Or from 92.74p to 142.3p.

But the current share price is 238p, implying a 63% premium to the last official NAV calculation. In other words, the stock might have got ahead of itself after basically doubling year to date.

Therefore, I think investors should consider avoiding this for now (or at least keeping it as a smaller speculative position). It may well keep going higher as SpaceX excitement builds, but there’s a large NAV premium to bear in mind.

If the SpaceX IPO bombs, or there’s a sharp market downturn, Seraphim Space could quickly lose altitude.

Ben McPoland has positions in Nvidia and Rolls-Royce. The Twelfth Magpie has recommended AJ Bell, Nvidia, and Rolls-Royce. Views expressed on the companies mentioned in this article are those of the writer and therefore may differ from the official recommendations we make in our subscription services such as Share Advisor and Hidden Winners.