We’re less than three months into 2026, but we’ve already seen some pretty massive movements in the S&P 500. While the index as a whole is down slightly since the start of the year, the same can’t be said for some of its constituents, with one already more than doubling!
Let’s explore the biggest winners of 2026 so far, and whether there might be even more growth on the horizon for the top contender.
Explosive returns
In order of share price gains since the start of January, the best performing S&P 500 stocks are:
- SanDisk Corp (NASDAQ:SNDK) – up 132%.
- Moderna – Up 83%.
- Texas Pacific Land Corp – Up 75%.
- Generac Holdings – Up 51%.
- Corning – Up 48%.
Delivering double-digit returns across an entire year can often be a challenge for many large-cap companies. So to see these businesses deliver such exceptional performance before the first quarter has even ended is undeniably impressive.
For reference, a £10,000 investment into an S&P 500 index fund at the beginning of 2026 is now worth around £9,880. But stock pickers smart enough to allocate this capital evenly across this basket of five US stocks are now sitting on roughly £17,780!
Of course, past performance doesn’t guarantee future returns. So blindly investing in these early winners, expecting them to continue outperforming, could backfire quite painfully.
With that in mind, let’s take a closer look at SanDisk.
Investigating SanDisk
SanDisk hasn’t been a public company for very long, having only joined the stock exchange in February 2025 following its spin-off from Western Digital.
However, despite its short tenure as a standalone business, the data storage device enterprise has delivered a jaw-dropping 1,600%+ return since its IPO.
The company specialises in NAND memory storage devices. Following a supply glut throughout 2024, SanDisk, along with Samsung and other NAND specialists, deliberately curtailed production capacity to stabilise prices.
However, skip ahead to late 2025, and demand’s skyrocketed. With hyperscalers drastically ramping up their artificial intelligence (AI) infrastructure spending and replacing traditional hard disk drives (HDDs) with faster NAND solid-state drives (SSDs) to handle AI workloads, the supply/demand dynamics have flipped.
As such, in its latest quarterly earnings report, SanDisk’s revenue jumped 61% year on year, gross margins expanded from 32.5% to 51.1%, and operating profits skyrocketed 386% from $233m to $1,133m.
With management guiding for even more gross margin expansion to as high as 67% in the next quarter, the growth journey for SanDisk shares looks far from over.
Taking a step back
As we’ve already seen in recent years, NAND memory pricing’s notoriously cyclical. And looking at its original parent company, Western Digital’s suffered multiple 50%+ multi-year declines.
If AI capex slows, the explosive momentum and excitement behind SanDisk shares could follow.
Alternatively, even if hyperscalers continue their spending spree, higher production volumes from rivals like Samsung could result in a supply surplus, sending NAND prices firmly in the wrong direction – something that’s happened multiple times in the past.
Overall, there’s a lot of understandable excitement surrounding this sector today. But with the share price already skyrocketing, it seems a lot of the anticipated future growth’s already priced in. As such, investors may be better off looking at other S&P 500 stocks for sustainable growth opportunities.
