Finance Matters Insights
What to know about the S&P500 and SpaceX IPO
If you're settling into the new tax year and still hoping to utilise your Stocks & Shares ISA to the best of your ability, here's a few things worth knowing about the markets right now.
📊 What actually makes up the S&P 500
You've probably heard of the S&P 500, even if you've never invested a penny. It's the index that tracks the 500 largest companies listed in the US and it's a popular way for people to invest in the American stock market through a single fund.
You buy the S&P500, you buy a slice of 500 different companies. It sounds like instant diversification (and it is, to a degree).
The reality however, is more concentrated than that.
As of early 2026, the top 10 companies make up roughly 38% of the entire index:
Top 10 companies:
- Nvidia (~7%)
- Alphabet, parent of google (~6.4%)
- Apple (~5.9%)
- Microsoft (~5.3%)
- Amazon (~4%)
- Broadcom (~2.5%)
- Meta (~2.5%)
- Berkshire Hathaway (~2%)
- Tesla (~2%)
- JPMorgan Chase (~1.5%)
* Data as of 22.05.26 - these percentages move week to week.
That means £4 of every £10 you invest in the S&P500 tracker is going into just 10 companies. The remaining £6 is spread across the other 490.
Eight of those are tech or tech-adjacent, and most are heavily tied to the AI landscape playing out right now. So if you're invested in the S&P 500 today, or planning to be, you're looking at significant exposure to a small handful of US tech giants.
It isn't a bad thing - these companies have driven enormous returns over the last decade but it's worth knowing because understanding your diversification spread helps you build your portfolio.
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🚀 SpaceX is heading to the public markets
Speaking of Tech and AI, one of the biggest stories right now is the potential SpaceX IPO.
As a reminder, an IPO (Initial Public Offering) is the moment a previously private company offers its shared to the public for the first time.
SpaceX is targeting a stock market listing early June with a valuation of up to $2trillion and a raise of around $75-$80billion. If it lands at those numbers. it'll be the largest IPO in history.
SpaceX isn't just a rocket company, it also owns Starlink (the satellite internet network with over 10 million users), X (previously Twitter) and Grok - it's effectively three businesses bundled into one.
For UK investors, you won't be able to buy SpaceX directly on the day it lists, but you'll likely gain exposure indirectly through global tracker funds and US-focused ETFs that will hold it once it becomes part of the major indices.
💡 What does any of this mean for you?
If you're already invested in an S&P500 tracker, you're more exposed to US tech than you might realise. A globally diversified fund (one that holds companies from the US, UK, Europe, Asia and emerging markets) would give you a broader spread.
If the SpaceX IPO catches your interest, you don't necessarily need to chase the listing day itself. Once it joins the major indices, global tracker funds will start holding it automatically and you'll get exposure without taking on a single-stock risk.
If none of this directly applies to you yet, hopefully it's still helpful insight to what's happening in the market, ahead of you becoming a confident investor.
F
Fisayo Martins
Founder at Finance Matters UK
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