Eye on the Market 2026 Outlook (J.P. Morgan, January 2026): 42 AI stocks drove up to 75% of S&P 500 profits

Michael Cembalest's annual outlook is this year a report on AI concentration. The market cap of four hyperscalers and the semiconductor companies they depend on grew from $3T to $18T in a few years, and a group of 42 AI-related companies has produced 65% to 75% of S&P 500 earnings, profits and capital spending since ChatGPT launched. Tech capital spending contributed 40% to 45% of US GDP growth over the prior three quarters, up from under 5% in early 2023. The report then stress-tests whether that moat holds, working through four medium-term risks: US power generation constraints, China scaling its own stack, Taiwan, and a possible metaverse moment in which $1.3T of capex and R&D fails to earn hyperscaler-level returns. For founders, the useful part is the capex math: it shows how dependent the startup ecosystem's compute supply and customer budgets are on a handful of balance sheets, and what would have to go wrong for that spending to pause.