Thus far, 2025 has been another good year for the stock market. The last month in particular has been especially strong, with the S&P 500 now up just over 15% year-to-date. While double-digit gains in the broader indexes are always welcome, what really grabs investor attention are the individual stocks delivering outsized returns.

Using the Zacks platform has been a fantastic way to identify some of these market leaders. In fact, every one of the stocks I’ll cover today has been highlighted on Zacks’ website numerous times over the course of this year. To narrow the list, I looked specifically at companies with a market capitalization over $10 billion and then filtered for both year-to-date performance and strong one-month returns.

Why add the one-month filter? Because many investors naturally hesitate to buy stocks at all-time highs, preferring to hunt for bargains. But history shows that buying strength, especially names consistently making new highs, can be one of the most powerful strategies. Trailing one-month returns are a strong bullish signal, often pointing to continued momentum ahead.

Of course, the highest-flying stocks often come with higher volatility, and these names are no exception. Additionally, each of these stocks have notably lofty valuations. But for investors looking for powerful momentum trading opportunities, these may fit into your portfolio.

Three stocks that stood out as 2025’s best performers so far are Oklo Inc. ((OKLO Quick QuoteOKLO - Free Report) ),IREN Limited ((IREN Quick QuoteIREN - Free Report) ), and Nebius Group N.V. ((NBIS Quick QuoteNBIS - Free Report) ). Unsurprisingly, each is firmly positioned in the heart of the artificial intelligence boom. Below, I’ll break down their performance and why they’re capturing investor enthusiasm.

Image Source: Zacks Investment Research

IREN Limited Stock Rallies Amid AI Pivot

IREN Limited is a vertically integrated data center company that built its reputation on powering cryptocurrency mining but has more recently pivoted aggressively into the AI infrastructure sector. A key differentiator for the company is that all of its facilities run entirely on renewable energy, giving IREN both a sustainable profile and a major cost advantage through some of the lowest power costs in the industry.

One of the most notable recent developments came in the last few weeks when IREN purchased 12,000 GPUs from NVIDIA in a deal worth over $600 million, bringing its GPU fleet to approximately 23,000 units. This is a massive step toward positioning the company as a major AI compute player, and it has been a key driver of the stock’s strong performance in 2025.

Unlike the other stocks I am sharing here, IREN Limited is actually earnings positive. That said, its earnings revisions have been volatile, with large swings higher and lower over the past two months, though the stock still currently carries a Zacks Rank #3 (Hold).

The growth outlook, however, is very strong. Sales are projected to grow 122% this year and another 64% next year. On the bottom line, earnings are expected to soar by nearly 1,600% this year, followed by an additional 34% increase next year.

Valuation is lofty, trading at about 66.9x forward earnings, but that’s actually the most reasonable multiple of the group I’ll be highlighting. Looking at the price action, IREN is essentially on the verge of making a new record high, pushing against the $48.80 level. A breakout above that resistance could open the door for another bull run. On the other hand, if shares slip below $43, momentum traders may prefer to wait for a better entry point.

Image Source: TradingView

Shares of Oklo Inc. Gain on Nuclear For AI Plans

Oklo Inc. is an advanced nuclear technology company focused on designing and deploying compact nuclear fission reactors that aim to deliver clean, reliable, and affordable power at scale. Its Aurora reactor is engineered with inherent safety features and is designed to operate for 10 years or more without refueling, which is a major potential advantage if the technology proves successful. This type of power is exactly what will be required as the data center boom progresses.

That said, this is easily the most speculative stock in the group. Despite boasting a nearly $20 billion market cap, Oklo currently has no sales or earnings, underscoring just how high-risk and future-oriented the story really is. The stock carries a Zacks Rank #3 (Hold), but has had some volatile earnings revisions.

On the positive side, Oklo recently broke ground on its first Aurora reactor at Idaho National Laboratory, a milestone that demonstrates progress toward commercialization. Still, any meaningful revenue stream is likely years away.

From a technical perspective, the stock experienced a minor correction over the last two weeks but has since broken out of a bull flag formation. As long as shares hold above the $119 level, momentum traders may expect the uptrend to continue. However, with speculative names like Oklo, once momentum breaks, downside can be swift, so risk management must be tight.

Image Source: TradingView

Nebius Group Stock Rockets Higher on Microsoft Partnership

Nebius is an AI infrastructure company that operates a “NeoCloud,” a specialized cloud computing platform designed for high-performance GPU and AI workloads. The company’s services leverage NVIDIA hardware and software to provide scalable AI compute infrastructure, putting it right at the center of the most powerful tech trend of the decade.

Nebius is still a net negative earnings company, making it a more speculative story. But the scale of its recent contract win underscores why investors are so excited. Nebius just announced a $17.5 billion deal with Microsoft, set to begin later this year, which validates its platform and highlights how quickly massive AI infrastructure deals can materialize.

Growth forecasts are eye-popping. Sales are expected to grow 220% next year, though profitability remains out of reach in the near term. The company’s earnings revisions trend has been volatile, but the stock currently carries a Zacks Rank #3 (Hold).

Price action has been nothing short of spectacular. Shares are making new record highs, breaking out of multiple bull flag patterns, and momentum remains firmly to the upside. For pattern traders, waiting for consolidation may provide a cleaner entry point. But for those comfortable buying strength, Nebius represents one of the purest momentum trades in the market right now. Position sizing and risk management are critical, as these high-octane names can move both ways quickly. That being said, Nebius is arguably the strongest stock in the market today, and it’s likely to remain a magnet for investor attention in the weeks ahead.

Image Source: TradingView

Should Investors Buy Shares in NBIS, IREN and OKLO?

There’s no question these are high-risk, high-reward names. Each of these stocks carries lofty valuations, volatile earnings trends, and in some cases, no revenue at all. But they also represent some of the most compelling themes in the market today—artificial intelligence, data center infrastructure, and next-generation power solutions.

For investors who are comfortable with volatility and know how to manage risk, the near-term momentum in these names could continue to drive outsized gains. With the market heading into year-end and investors chasing performance, it’s not hard to imagine these leaders attracting even more attention.

That said, these stocks are best suited for traders and aggressive growth investors. They’re not steady compounders, and they’re not cheap. But in markets like this, the strongest stocks often keep getting stronger. If momentum remains intact, NBIS, IREN, and OKLO may continue to be some of the best performing stocks in 2025.