The Eerie Parallels Between AI Mania and the Dot-Com Bubble
Bulls deny that there’s a 1990s-style bubble in AI. There are a few striking similarities, and some notable differences.
By James Mackintosh, The Wall Street Journal, Dec. 13, 2025
Valuation
There are lots of ways of valuing stocks, and pretty much all of them make U.S. shares look the most expensive since the dot-com bubble. The forward price-to-earnings ratio, price to cash flow, the “Fed model” calculation of the extra reward offered by stocks compared with bonds and the cyclically adjusted PE ratio all scream that stocks are expensive.
…
Investment
…
The [fiber optic buildout] numbers in 2000 were immense, with well over $100 billion being sunk into new telecom networks in the late 1990s. There was so much fiber that much of it ended up mothballed for a decade before internet traffic expanded enough to justify using it.
The race to build data centers is even more extreme, with investment figures in the trillions thrown around by leading AI developers. Spending is so large that economists say it’s making up a significant share of gross domestic product growth…
Retail trading
Individuals are dominating stock trading, again betting big on tiny loss-making companies. In both the 2000 bubble and the 2021 bubble in SPACs, clean tech, crypto and cannabis, loss-making small stocks far and away beat profitable small stocks, which are much less exciting.
… [end quote]
I have discussed the high valuations and over-investment before but the last point is new to me. I didn’t know that there is an S&P 600, a small-cap index which requires companies to show profits before being included.
The point is that retail traders are being influenced by exciting stories and speculating on stocks without caring whether they are profitable. This carries over from the larger AI story to smaller speculations.
The record amount of margin debt that is driving the stock market continues to rise rapidly. (These are debit balances in customers’ securities accounts. I made a nifty chart but it wouldn’t copy into this post.)
| 09/01/20 | 654,324 |
|---|---|
| 10/01/20 | 659,313 |
| 11/01/20 | 722,118 |
| 12/01/20 | 778,037 |
| 01/01/21 | 798,605 |
| 02/01/21 | 813,680 |
| 03/01/21 | 822,551 |
| 04/01/21 | 847,186 |
| 05/01/21 | 861,626 |
| 06/01/21 | 882,103 |
| 07/01/21 | 844,324 |
| 08/01/21 | 911,545 |
| 09/01/21 | 903,117 |
| 10/01/21 | 935,862 |
| 11/01/21 | 918,598 |
| 12/01/21 | 910,021 |
| 01/01/22 | 829,637 |
| 02/01/22 | 835,255 |
| 03/01/22 | 799,660 |
| 04/01/22 | 772,940 |
| 05/01/22 | 752,944 |
| 06/01/22 | 683,445 |
| 07/01/22 | 696,781 |
| 08/01/22 | 687,787 |
| 09/01/22 | 664,009 |
| 10/01/22 | 649,618 |
| 11/01/22 | 643,783 |
| 12/01/22 | 606,659 |
| 01/01/23 | 641,228 |
| 02/01/23 | 624,379 |
| 03/01/23 | 645,429 |
| 04/01/23 | 631,949 |
| 05/01/23 | 644,170 |
| 06/01/23 | 681,228 |
| 07/01/23 | 709,834 |
| 08/01/23 | 689,185 |
| 09/01/23 | 680,846 |
| 10/01/23 | 635,276 |
| 11/01/23 | 660,887 |
| 12/01/23 | 700,774 |
| 01/01/24 | 701,975 |
| 02/01/24 | 742,963 |
| 03/01/24 | 784,136 |
| 04/01/24 | 775,464 |
| 05/01/24 | 809,431 |
| 06/01/24 | 809,322 |
| 07/01/24 | 810,835 |
| 08/01/24 | 797,162 |
| 09/01/24 | 813,211 |
| 10/01/24 | 815,369 |
| 11/01/24 | 890,852 |
| 12/01/24 | 899,168 |
| 01/01/25 | 937,253 |
| 02/01/25 | 918,144 |
| 03/01/25 | 880,316 |
| 04/01/25 | 850,558 |
| 05/01/25 | 920,960 |
| 06/01/25 | 1,007,961 |
| 07/01/25 | 1,022,548 |
| 08/01/25 | 1,059,723 |
| 09/01/25 | 1,126,494 |
| 10/01/25 | 1,183,654 |
| 11/01/25 | 1,214,321 |
When a bubble bursts the margin calls often force the sale of all assets, both good and bad. The baby gets thrown out with the bath water. This is what makes bursting bubbles so dangerous to stock investors.
The Price-to- earnings ratio based on average inflation-adjusted earnings from the previous 10 years, known as the Cyclically Adjusted PE Ratio (CAPE Ratio), is 40 compared with the long-term median of 16. This aligns with the other valuation metrics discussed above.
The stock indexes are continuing their rising trend despite some noise. VIX is low. The Fear & Greed Index is still in Fear but it is rising. The trade is risk-on as stocks and junk bonds have been rising relative to the 10 year Treasury.
USD has stabilized (with noise) at the lower level it reached in April 2025. Gold, silver and copper are rising strongly. Bitcoin has stabilized after a steep drop.
The Federal Reserve cut the fed funds rate by 0.25% as expected last week. There was lack of unanimity since the economy is still growing strongly and inflation is rising faster than the Fed’s target.
The Atlanta Fed’s GDPNow model estimate for real GDP growth (seasonally adjusted annual rate) in the third quarter of 2025 was 3.6 percent on December 11. That is a strong growth reading. The Cleveland Fed’s inflation forecast is over 3% for the CPI which feeds into TIPS, I-Bonds and the adjustment for Social Security.
The Treasury yield curve shows an important pushback from the bond market. Even though the fed funds (overnight) rate dropped the longer maturity yields rose. This shows that the bond market is pricing in higher uncertainty regarding inflation and the overwhelming borrowing needs of the government. The bond market isn’t following the Fed in cutting yields.
The Chicago Fed’s National Financial Conditions Index (NFCI), which provides a comprehensive weekly update on U.S. financial conditions in money markets, debt and equity markets, and the traditional and “shadow” banking systems, shows that already loose conditions are getting looser.
However, financial stress has been increasing. As a result, the Federal Reserve announced that it will start buying $40 billion per month of short-term Treasuries to increase liquidity in the banking system. They say that this isn’t Quantitative Easing, but if it walks like a duck and quacks like a duck…This will reverse the oh-so-gradual decline of their prior gigantic QE assets.
Whatever it’s called, pumping more money into banks will increase asset prices.
There are no dramatic news stories that will shift the markets this week.
The METAR for next week is sunny.
Wendy


