As AI bubble fears circulate, remember the railroad bust of 1873

AI stock bubble talk is percolating again as Nvidia (NVDA), AMD (AMD), and Micron (MU) push to record highs. While the pundits love comparing what we are witnessing with Big Tech stocks to the lead-up to the dot-com crash in the early 2000s, don't overlook how this moment is also creeping up on the railroad bust in the late 1800s. As the chart below from Bank of America strategist Michael Hartnett shows, peak concentration for most asset bubbles in history has been capped around the 40% level, except for during the railroad boom.Bubble tracking. The railroad bust of 1873 was a massive financial collapse driven by speculation in railroad construction. This ultimately led to the Panic of 1873.