Stocks moving after hours: Amazon, Apple, Steel Dynamics and more

After the bell, several high-profile names led trading activity as Amazon’s expanded deal with Anthropic, Apple’s announced leadership transition and mixed results from Steel Dynamics grabbed investor attention. These developments pushed volatility in extended trading sessions across US equities.

Amazon said it will invest $5 billion immediately in Anthropic and could provide up to an additional $20 billion tied to commercial milestones, while Anthropic committed to spending more than $100 billion on Amazon’s cloud technologies over the next decade. The announcement—part of a broader strategic partnership that includes access to Trainium chips—prompted a positive after-hours response in Amazon shares as markets reassessed AWS demand and long-term capital expenditure implications.

Apple confirmed that Tim Cook will become executive chairman effective September 1, 2026, and John Ternus, currently senior vice president of Hardware Engineering, will assume the company’s chief executive role. The succession plan, published on Apple’s newsroom, triggered modest after-hours weakness in the stock as investors weighed governance and product roadmap continuity implications.

Steel Dynamics reported a mixed first-quarter picture with revenue slightly above consensus while EPS came in roughly in line with estimates. That kind of mixed print typically leaves industrial names sensitive to follow‑on guidance, scrap and aluminum price moves and macro demand signals; Steel Dynamics’ shares showed movement in extended trading as traders digested the details.

Market strategists say the cluster of headlines highlights two persistent themes for investors: the strategic premium being placed on AI infrastructure and cloud partnerships, and the continued vulnerability of cyclicals to input‑price swings and demand visibility. Traders will watch intraday prints and company conference calls for further clarity, with after‑hours reactions likely feeding into next day’s opening price discovery.