Advanced Micro Devices (AMD) shares tumbled in New York trading on Monday, dragging down UK-listed technology stocks after a Wall Street broker downgrade reignited fears about a slowdown in the semiconductor market.
The stock dropped more than 4% to $138.50 after Morgan Stanley lowered its rating on the chipmaker from 'overweight' to 'equal-weight', citing a softening outlook for non-artificial intelligence chips and a possible pause in enterprise spending. The move erased roughly $8bn from AMD's market value and sent ripples through the tech sector on both sides of the Atlantic.
In London, shares in IQE, the Cardiff-based semiconductor wafer supplier, fell 2.8%, while Scottish Mortgage Investment Trust, which holds a significant position in AMD, declined 1.1%. The broader FTSE 100 edged down 0.3% to 8,212, with the technology sub-index among the worst performers.
Analysts at Morgan Stanley argued that while AMD's AI chip business remains strong, the company's traditional PC and server chip segments face headwinds from a normalising demand cycle and intensifying competition from Intel and Nvidia. 'The near-term risk-reward looks less favourable given the lack of catalysts and potential for further earnings estimate cuts,' the broker wrote in a note to clients.
For UK investors and pension holders with exposure to global tech funds, the AMD weakness serves as a reminder of the sector's sensitivity to shifts in demand. The Philadelphia Semiconductor Index, a benchmark for chip stocks, fell 1.8% on the day, reflecting a broader reassessment of valuations after a strong rally in the first half of 2026.