Triple-Digit Club: A Wave of Stocks Have Seen Huge Gains in 2026

Key Takeaways

• The AI infrastructure boom has driven an outsized number of stocks to gains of 100% or more in the past year, Morningstar data shows.
• A few of these stocks, including SanDisk, have risen over 1,000% in the past 12 months.
• Morningstar analysts say all but a few of these “triple-digit” stocks are overvalued, and only a handful have durable competitive advantages.

Thanks to the artificial intelligence wave, the club of stocks surging more than 100% has become a little less exclusive.

In the past year, 42 stocks in the Morningstar US Large-Mid Market Index have more than doubled, attaining triple-digit-percentage gains as of June 8. That’s more than twice the ten-year average. In the past six months alone, 12 stocks are up over 100% each. The vast majority of these gains can be attributed to the AI infrastructure boom.

Leaders of the triple-digit club over the past year include semiconductor supplier SanDisk SNDK, which is up an off-the-charts 4,094.1%, an eyewatering early year after its February 2025 spinoff from parent company Western Digital WDC. Next is energy-server company Bloom Energy BE, up 1,064.2%. Bloom recently won a partnership with enterprise IT company Oracle to supply power to its AI data centers.

“The expansion of the ‘triple-digit club’ reflects massive capital expenditure on AI,” says Morningstar Indexes strategist Dan Lefkovitz. “Many of the big winners are suppliers of AI ‘picks and shovels,’ whether it’s chips, memory, or data centers.”

The triple-digit club is bigger than usual in terms of both quantity and magnitude. Tech and industrials make up the majority of the list. Morningstar analysts believe most of these stocks are overvalued and lack durable competitive advantages, with a few key exceptions. Should the market turn against AI, investors would be exposed to potentially heavy losses.

Stocks in the Triple-Digit Club

The latest count of 42 stocks passing the 100% performance threshold for the last year is higher than has typically been the case. On average over the past 10 years, just 19 stocks within the US Large-Mid Market Index’s list of over 500 passed in any given month.

But it’s not only the number of companies crossing into triple-digit territory that’s elevated; it’s also the scale of those gains. And it all comes from the common theme of AI infrastructure. The median gain among the 100%+ group stands at 182% for May 2026, 50 percentage points above where it stood ten years ago and 40 points above its 10-year average median.

Currently, six stocks in the index have risen over 500% in the past year: SanDisk, Bloom, hard-disk drive supplier Western Digital (up 851%), memory and storage chip specialist Micron Technology MU (up 774.9%), hard disk drive supplier Seagate Technology STX (up 592.8%), and high-speed optical provider Ciena CIEN (up 541.7%). The last time six or more stocks gained over 500% each was the 12 months leading up to September 2025. This was a less thematically unified assortment: independent power producer Oklo OKLO, aerospace and defense company Rocket Lab RKLB, advertising conglomerate AppLovin APP, retail trading platform Robinhood HOOD, and two tech stocks.

Technology and Industrials Sectors Drive Triple-Digit Gains

Technology stocks have long been highly concentrated in this realm, but the trend is even stronger now. Currently, 60% of all stocks in the triple-digit club (versus just 38% on average over the past 10 years, the highest of any sector) are part of the technology sector. The rest come from the industrials, communication services, energy, and basic materials sectors.

“Clearly, a rising AI tide is lifting all boats,” Lefkovitz says. “From a sector perspective, technology and tech-adjacent sectors like communication services have benefited most. From a style perspective, it’s a growth story.”

By industry, representation is heavy in semiconductors, semiconductor equipment and materials, electronic components, and computer hardware. Of the 42 triple-digit stocks, 12 are semiconductor or semiconductor equipment and materials companies. The group’s top performer is memory and storage chip specialist Micron, up 774.9% in the 12 months through June 8. Next is longtime chip giant Intel INTC, up 449.7% for the period.

Historically, sector representation among triple-digit performers has been wider. Take 2021, when stocks showed a strong recovery from their March 2020 covid-induced lows. Names from nine of the 11 Morningstar sectors made the triple-digit list, led by Tesla TSLA and Pinterest PINS.

Triple-Digit Stocks and Moats

Currently, none of the five top-performing triple-digit stocks has earned an economic moat rating. Among the top ten, just Ciena and Marvell have narrow moats, meaning Morningstar analysts think they can maintain a competitive edge for at least 10 years. Semiconductor testing equipment provider Teradyne carries a wide economic moat, meaning we expect it to outcompete its rivals over the next 20 years or more.

Among the 42 triple-digit stocks of May 2026, 17 have no moat, 11 have narrow moats, and eight have wide moats. The rest have not been evaluated.

Are These Triple-Digit Stocks Still Buys?

Currently, almost all the stocks on the triple-digit list are overvalued. Of the 29 triple-digit stocks of May 2026 covered by Morningstar, 18 (just over 60%) have two-star ratings, signifying moderate overvaluation. Three are significantly overvalued, and six are fairly valued.

Even after triple-digit runups, two stocks remain undervalued. The first is Google parent company Alphabet GOOG/GOOGL, which trades at a 16% discount to its Morningstar-assessed fair value estimate of $433 per share. Also undervalued is computer storage and networking company Hewlett Packard Enterprise HPE, trading at a 25% discount to its fair value estimate of $64 per share. Senior equity analyst Seth Goldstein wrote in a recent note on the company: “Hewlett Packard reported stellar second-quarter results that fundamentally shift the timeline of its formerly multiyear turnaround.” He says better revenue growth from strong GP server sales was a key driver, driven by the agentic AI trend.

Should Investors Be Worried?

Amid high-flying stocks in the triple-digit club, “Concentration risk in the US stock market has increased,” Lefkovitz says. The technology sector represents 37% of the US market as of May 2026, by his measure. “That surpasses Internet Bubble-era levels. The US stock market has become increasingly dependent on the AI theme. Lately, that dependence has benefitted investors.” But it can also be a source of volatility: “If sentiment or fundamentals turn against the AI theme, it exposes investors to potential losses.”

Which Stocks Are in the Triple-Digit Club Now?

Here is our full list of stocks in the triple-digit club: