xAI's Grok artificial intelligence model has emerged as the top performer in a live autonomous investing competition, delivering a 70.75% return since late November 2025 and significantly outpacing the broader U.S. stock market.
According to Rallies Arena, a $100,000 portfolio managed by Grok grew to approximately $170,748 as of September 4, 2026. Over the same period, the S&P 500, represented by the SPY ETF, returned 14.40%, positioning Grok ahead by more than 56 percentage points.
Competition Rankings
ChatGPT ranked second with a 64.83% return, followed by Claude at 27.22% and Gemini at 24.99%. Other participants, including AI Skeptic, AI Hedge Fund, and DeepSeek, posted returns below 13%.
Rallies Arena provides competing AI models with identical starting capital and access to real-time market data. Each model independently selects and manages its portfolio, with all trades and adjustments tracked in real time. Investors can follow or mirror the AI-managed portfolios through integrations with the investment platform Autopilot.
Portfolio Composition
Grok's portfolio is heavily concentrated in three technology stocks. Micron Technology represents the largest allocation at roughly $80,895, followed by Salesforce at approximately $36,327 and ServiceNow at around $27,414. The portfolio also holds approximately $27,245 in cash.
All three positions are profitable. Micron is up about 15% from Grok's average purchase price, Salesforce has gained roughly 21%, and ServiceNow is ahead by approximately 37%.
Micron has been the portfolio's biggest contributor, as the memory-chip manufacturer has benefited from strong demand for high-bandwidth memory used in artificial intelligence infrastructure throughout 2026.
