The rising values of artificial intelligence stocks and their outperformance compared to other S&P 500 stocks in 2026 has former hedge fund manager Whitney Tilson sending a bubble warning. Here’s why.

Whitney Tilson Smells a Bubble

Tilson draws a parallel between today’s AI trade and the technology stocks that drove the dot-com bubble to its March 2000 peak.

Here are the top 10 best-performing stocks in the S&P 500, which is tracked by the SPDR S&P 500 ETF Trust (NYSE:SPY) (as of 8/14/26), as shared by Charlie Bilello, with their industry and year-to-date gains listed below:

  • Sandisk Corp (NASDAQ:SNDK): technology hardware, +591.3%
  • Dell Technologies (NASDAQ:DELL): technology hardware, +293.5%
  • Seagate Technology Holdings (NASDAQ:STX): technology hardware, +254.4%
  • Micron Technology (NASDAQ:MU): semiconductors, +240.7%
  • Western Digital Corp (NASDAQ:WDC): technology hardware, +195.6%
  • Intel Corp (NASDAQ:INTC): semiconductors, +177.8%
  • Marvell Technology (NASDAQ:MRVL): semiconductors, +161.6%
  • Lumentum Holdings (NASDAQ:LITE): communications equipment, +151.3%
  • Hewlett Packard Enterprise Co. (NYSE:HPE): technology hardware, +146.6%
  • Advanced Micro Devices (NASDAQ:AMD): semiconductors, +140.2%

All 10 stocks are AI-related names and benefiting from the AI trade, Tilson said in a newsletter Tuesday.

For comparison, Tilson asked AI chatbots about the top-performing stocks during the dot-com bubble. Tilson used March 10, 2000, as that was the day the Nasdaq Composite Index peaked.

"Give me the definitive historical-constituent top 10 S&P 500 stocks with exact December 31, 1999 to March 10, 2000 percentage gains," Tilson’s prompt reads.

ChatGPT was the only bot to return a close answer. Here are the 10 stocks that fit the criteria:

  1. NetApp
  2. Qualcomm
  3. Analog Devices
  4. Oracle
  5. Lam Research
  6. Teradyne
  7. Applied Materials
  8. Corning
  9. Adobe Systems
  10. Apple

Tilson highlights that all 10 of those stocks at the peak of the Nasdaq index before the dot-com bubble were technology related, "reflecting the Internet craze at the time."

"It reminds me of what Mark Twain is reputed to have said: ‘History doesn’t repeat itself, but it often rhymes.’"

Read Also: Nvidia Is the Best S&P 500 Stock of the Past 10, 15, 20 Years — but 4 Stocks Beat It Over the Past 5 Years

Jim Cramer’s Bubble Indicator

Another bubble indicator may have to do with television personality Jim Cramer, Tilson wrote recently.

"There’s little doubt in my mind that we’re in a similar AI bubble right now – but I’m much less certain how much further it will inflate and when exactly it will burst," Tilson said.

The latest indicator for Tilson was when Cramer visited an Idaho construction site for a Micron Technology semiconductor plant.

Cramer said at the time that "Micron’s stock is radically undervalued."

Tilson said this could put the bubble near its peak.

"This is significant because, for decades, Cramer has been a great contra-indicator."

Tilson highlighted a speech of the "Winners of the New World" from Cramer on Feb. 29, 2000 when he named 10 internet-related stocks.

"I wouldn’t own any other stocks in the year 2000," Cramer said at the time.

Tilson said that 15 months after Cramer’s speech, the 10 stocks had lost over 80% of their value. Nine years later, the 10 companies were all either bankrupt, delisted, or acquired at a lower price than their pre-bubble valuation.

"I think history is likely to repeat itself with the AI bubble."

Read Also: SpaceX Stock Overvalued By $1 Trillion: Former Hedge Funder Says ‘Most Overvalued Large Cap Stock of All Time’

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