US retail investors are increasingly delegating stock-market decisions to AI agents, with brokerages including Robinhood and Webull allowing customers to connect tools such as Claude and Codex to analyze signals and execute trades. The shift lowers the technical barrier to algorithmic trading: users can issue natural-language instructions for tasks ranging from screening data and placing orders to trading around oil prices, options returns or presidential social-media activity. Moomoo opened agent trading in April, and CEO of Moomoo's US operations Neil McDonald expects AI agents to account for roughly 20% of platform trading volume by year-end. Early users report substantial gains, although the National Bureau of Economic Research has found that AI-designed strategies tend to favor concentrated portfolios of high-valuation and heavily covered companies without outperforming simple index strategies. Researchers and market specialists also warn that agents using similar public data could crowd into the same positions and amplify volatility. Robinhood says it segregates AI-managed portfolios and notifies users whenever trades occur. The development was also discussed in the daily What’s News newsletter, which is offered free by email to subscribers.