Nebius Group vs. Amazon: Which AI Cloud Stock Has More Room to Run?

Nebius Group (NBIS) reported a ninefold surge in AI cloud revenue to $105.1 million in Q2 2025 and raised its ARR outlook to $900M-$1.1B, signaling rapid growth but also facing significant capital expenditure and intense competition. Conversely, Amazon's AWS, a dominant force in AI cloud infrastructure, achieved $33 billion in Q3 2025 revenue, up 20.2%, driven by proprietary AI chips and substantial infrastructure expansion. While both benefit from the expanding AI market, the analysis highlights NBIS's overvaluation and higher risk profile compared to AMZN's strong market position and more favorable valuation, resulting in a Zacks Rank of #4 (Sell) for NBIS versus #2 (Buy) for AMZN.

Analysis

The AI cloud infrastructure market is projected to exceed $200 billion by 2028, driving significant growth for key players like Nebius Group (NBIS) and Amazon Web Services (AWS). NBIS, an emerging challenger, reported a ninefold surge in AI cloud revenue to $105.1 million in Q2 2025, while AWS, the established leader, achieved $33 billion in Q3 2025 revenue, marking 20.2% year-over-year growth. Both companies are expanding capacity, with NBIS raising its ARR outlook to $900M-$1.1B and AWS projecting Q4 2025 net sales between $206.0B and $213.0B.

Nebius's rapid expansion, evidenced by a 625% total revenue increase and new product launches, positions it as a fast-growing AI-native provider. However, its aggressive growth strategy entails substantial capital expenditure, with a reaffirmed 2025 capex guidance of $2 billion, posing execution risk amidst intense competition. The company also faces valuation concerns, trading at a Price/Book of 7.75X and receiving a Zacks Value Score of 'F' and a Zacks Rank #4 (Sell).

Amazon's AWS maintains market dominance through vast data center capacity and proprietary silicon, including Trainium and Graviton chips, with Trainium2 revenue growing 150% quarter-over-quarter. AWS is undertaking one of the largest infrastructure expansions, adding 3.8 gigawatts of power in the past year, supporting its comprehensive AI software ecosystem like Bedrock and SageMaker. This robust position is reflected in its 'A' Value Score and Zacks Rank #2 (Buy), despite a P/B of 7.12X.

Key Decisions for Investors

• Investors should exercise caution with Nebius (NBIS) due to its high capital intensity, significant competitive pressures, and current 'Sell' rating, closely monitoring its ability to sustain revenue growth against substantial capex and valuation concerns.
• Amazon (AMZN) presents a more stable investment opportunity in the AI cloud sector, supported by AWS's dominant market share, proprietary technology, aggressive infrastructure expansion, and favorable 'Buy' rating and valuation.
• Consider the differing risk-reward profiles inherent in established leaders versus high-growth challengers within the rapidly expanding AI infrastructure market, prioritizing companies with strong fundamentals and clear competitive advantages.