Financial bubbles are notoriously difficult to define in real time — until the moment they burst. There are at least four ways to determine when a bubble is building in financial markets. Much like the 1980s Japanese bubble and the 1999-2001 dot-com bubble, the situation today may reflect a good, old-fashioned misallocation of capital, as everyone chases the new, shiny technology. Indicators to watchAssuming we are indeed in a bubble, the next question concerns when it will deflate or burst. Judging by current market sentiment and positioning, the AI story seems closer to the 1996-97 stage of the dot-com bubble than to 1999-2001.