Artificial intelligence (AI) has been one of the most powerful investing themes of the decade. And for shareholders of Arm Holdings (NASDAQ:ARM) and Marvell Technology (NASDAQ:MRVL), the rewards have been extraordinary. Both stocks have delivered gains of more than 250% this year, making them among the top stocks to buy for 2026 to date.
The obvious question now is whether investors have missed the opportunity. After such huge gains, can these AI leaders continue climbing, or has too much optimism already been priced into their shares?
Let’s take a look at the numbers.
How much could this winning AI investment have made?
The scale of the AI rally has been remarkable.
An investor who bought £10,000 of both stocks at the start of the year would be sitting on a chunky pot worth £36,200. And considering we are still in the first half of 2026, that is truly incredible.
That’s the kind of return that can dramatically alter a Stocks and Shares ISA or SIPP portfolio.
These kinds of returns used to be limited to tiny high-risk penny stocks. But Arm Holdings and Marvell Technology are technology giants worth $447b and $253b respectively.
The reason behind these gains is straightforward. AI infrastructure spending has exploded. Technology giants are investing billions in data centres, networking equipment, and chips that run increasingly sophisticated AI models.
Arm and Marvell may not be household names, but they both occupy important positions in the AI ecosystem. Arm is actually a British chip designer based in Cambridge.
Meanwhile, Marvell provides the networking and connectivity solutions needed to move vast amounts of data around AI infrastructure.
Still the top stocks to buy today?
Nvidia’s CEO Jensen Huang recently declared Marvell as the “next trillion-dollar company”. If his projection proves to be correct, investors would see a fourfold return if they were to invest in Marvell shares today.
Marvell focuses on the infrastructure behind AI. What I find particularly attractive about Marvell is its exposure to multiple AI growth drivers. For instance, it benefits not only from AI training, but also the networking requirements needed to support future AI technology.
It’s a business with strong sales and profits. With its return on capital employed of 17% and healthy profit margin, I would consider it to be a high-quality share.
Can high expectations be met?
But expectations for future growth are high. If AI spending growth slows or if customer demand fails to meet lofty expectations, the highly valued shares could experience significant volatility.
The same risks apply to ARM. In fact, I would argue that ARM is the slightly riskier proposition with an even loftier valuation. Also, a large proportion of Arm’s licencing sales come from a relatively small group of customers. If key partners reduce orders or develop alternative technologies, future sales growth could be affected.
For investors looking at AI and wondering if they’ve missed the boat, I think AI adoption still appears to be in its early stages.
All things considered, I’m optimistic. I already have enough exposure to the sector, but with careful position sizing and diversification, investors should consider adding both to their stocks-to-buy list.
Should you invest £5,000 in Arm Holdings right now?
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Harshil Patel does not hold positions in the companies mentioned.
