The speculative tech bubbles of US artificial intelligence sector

This study identifies speculative bubbles in leading AI- US stocks from 2014 to 2025. By using the Generalized Supremum Augmented Dickey-Fuller methodology, multiple bubble episodes are detected during the pandemic-induced market exuberance from 2020 to 2022, and then after the excessive AI optimism post 2023. Interestingly, the panel analysis of all companies reveals synchronized speculative behavior that is found to be driven by liquidity, financial market stress and economic uncertainty. The investors’ sentiment is also found to influence bubble formation. These results highlight the importance of fundamentally assessing the longer-term prospects of the AI markets.