Evidence of Speculative Excess in AI-Related Semiconductor Stocks: A Comparative Analysis of Valuation Multiples and Fundamental Performance (2021-2026)

This study investigates whether the rapid valuation expansion observed in AI-related semiconductor equities during the 2021-2026 generative AI boom represents a speculative asset bubble or a fundamentally backed structural expansion. Utilizing a quantitative comparative design, financial metrics—including Price-to-Earnings (P/E), Price-to-Sales (P/S), revenue growth, EPS growth, and operating margins—were analyzed across six industry-leading semiconductor firms: Nvidia, AMD, Broadcom, TSMC, ASML, and Micron. The empirical findings reject the broad hypothesis of a universal speculative bubble for core industry leaders, while revealing localized speculative spillover in secondary market peers. Market leader NVIDIA demonstrated unprecedented operational growth (revenue growth exceeding 114-125% and EPS growth over 600%), which resulted in multiple compression (P/E compressing from 119.77x to 38.30x) rather than unbacked price inflation. Conversely, fabless competitors such as AMD and Broadcom exhibited signs of speculative excess, with valuation multiples expanding significantly ahead of realized revenue growth. Critical supply chain monopolies (TSMC and ASML) maintained grounded valuations throughout the period. The study concludes that investor evaluation during technological shifts requires granular, firm-level fundamental tracking rather than generalized sector-wide assumptions.