AI Stocks Down 16% From High: When Does It Become a Bubble Pop?

Pull up a chair, fans. The AI team is in a deep cold streak, and everyone in the stands is shouting "bubble." Before you join the chant, let's check the scoreboard and the rulebook.

Play 1: The scoreboard

Silicon Sideline News Network tracks the AI Economy Index. Think of it as one team's season record built from 143 publicly traded companies that make AI happen: the chipmakers, cloud giants, power suppliers, data center builders and the long-shot rookies. Our comparison is the NASDAQ Composite, the big tech-heavy league average. The NASDAQ is not part of our index.

How we keep score:

• Day one was 5 October 2026. The index started at 100 that day and set its high so far the next day, 6 October, at 101.09.
• Each company gets a weight, like minutes on the court. Bigger companies get more minutes, but no company gets more than 3% of the whole index. Weights come from stockanalysis.com market values as of 2 October 2026.
• Daily closing prices come from Yahoo Finance. NASDAQ closes are checked against Nasdaq's own page.
• Three squads:
• Major (40 companies, about 60% of the index): the stars, including Nvidia, Alphabet, Microsoft, Amazon, Meta, TSMC, Broadcom, Tesla, Micron, AMD, ASML, Intel, Oracle and Palantir.
• Minor (88 companies, about 40%): the supporting cast that powers and builds the stadium, including Caterpillar, Texas Instruments, Vertiv, Equinix, Constellation Energy, Lumentum, Cadence, Synopsys and CoreWeave.
• Frontier (15 companies, about 0.2%): the rookies on small contracts, like IonQ, Rigetti, AST SpaceMobile, Aurora, Pony AI, Planet Labs and Karman.

The full roster is at the end of this story.

The box score through Monday 2 November (our arithmetic, Yahoo Finance closes, and every drawdown is measured from the 6 October high close):

• AI Economy Index: 6 Oct high 101.09, 2 Nov close 84.65, Monday -2.6%, -16.3% from the 6 Oct high
• Major squad: 6 Oct high 100.38, 2 Nov close 83.27, Monday -2.6%, -17.1% from the 6 Oct high
• Minor squad: 6 Oct high 102.14, 2 Nov close 86.74, Monday -2.5%, -15.1% from the 6 Oct high
• Frontier squad: 6 Oct high 102.65, 2 Nov close 79.67, Monday -3.4%, -22.4% from the 6 Oct high
• NASDAQ Composite: 6 Oct high 27,599.79, 2 Nov close 25,164.32, Monday -1.1%, -8.8% from the 6 Oct high

Why our homepage shows a different number: the homepage's -15.4% is measured from day one, 5 October, when the index started at 100. Every figure in this story is measured from the 6 October high of 101.09.

Put simply: the AI team is falling nearly twice as fast as the league average. Why? Reuters (30 Oct) pointed to disappointing quarterly results from Alphabet and Amazon and a near-29% one-day drop in Intel. All of that fed questions about who pays for the AI building boom.

Play 2: What does a "bubble pop" actually mean?

Everyone's yelling "bubble." Let's look at the actual rulebook.

• Correction: a fall of 10% or more from a recent high (Fidelity Learning Center). Think of it as a cold streak.
• Bear market: a fall of 20% or more in a broad index. The SEC's Investor.gov glossary adds that it lasts "over at least a two-month period," with gloomy mood. Think of it as a down season.
• Bubble pop: there is no official line. Nobody blows a whistle. The label usually gets handed out afterward, once prices have fallen deep and stayed down, and the story everyone believed has broken.

The classic tape: the NASDAQ Composite closed at 5,048.62 on 10 March 2000 and hit 1,114.11 on 9 October 2002. That's a fall of about 78% over roughly two and a half years (Swoopr market history). It didn't close back above that 2000 level until 23 April 2015 (Swoopr market history). The internet itself kept growing. The prices people paid at the top were the problem.

How far is each team from each line? (our arithmetic, highs are the 6 Oct closes)

• AI Economy Index: -16.3% from high, already past the correction line (-10%), bear line (-20%) at 80.87, about 4.5% more
• Major squad: -17.1% from high, already past the correction line (-10%), bear line (-20%) at 80.31, about 3.6% more
• Minor squad: -15.1% from high, already past the correction line (-10%), bear line (-20%) at 81.71, about 5.8% more
• Frontier squad: -22.4% from high, already past the correction line (-10%), bear line (-20%) at 82.12, already below it
• NASDAQ Composite: -8.8% from high, correction line (-10%) at 24,839.81, about 1.3% more, bear line (-20%) at 22,079.83, about 12.3% more

So ask yourself: Is a 16% slide from the high in four weeks a cold streak or the start of a down season? Does the two-month part of the SEC definition matter when the index is only 21 sessions old? If the rookies are already past the bear line, are they a warning sign or just the usual long-shot swings? And would anyone call it a bubble before the story breaks?

We aren't calling it. The scoreboard isn't either, not yet.

Final whistle

Four weeks, 21 sessions, and a 16.3% slide from the high. The stars and the supporting cast are past the cold-streak line. The rookies have already fallen more than 20% from their high. The full team is about 4.5% from down-season territory. Whether anyone ever calls it a bubble depends on what comes next, and that part hasn't been played yet.

What to watch:

• Does the AI Economy Index stay above 80.87, its 20% line?
• Does the NASDAQ cross its 10% line at 24,839.81?
• Do the Major squad's stars stay above their 20% line, or follow the rookies?

So which is it: a cold streak, or the start of a down season?

Full roster (143 companies, weights as of 2 Oct 2026)

Major (40): AMD, AMZN, AVGO, GOOGL, META, MSFT, MU, NVDA, SPCX, TSLA, TSM, ASML, INTC, CSCO, ORCL, LRCX, AMAT, PLTR, DELL, ARM, BABA, ANET, GEV, KLAC, SNDK, MRVL, CRWD, STX, APH, IBM, QCOM, BLK, ETN, WDC, NEE, GLW, NET, SNOW, ISRG, NOW

Minor (88): CAT, TXN, RTX, TM, TT, EQIX, PWR, ASX, ADI, VRT, JCI, CDNS, DE, CEG, HPE, LITE, BE, SNPS, DLR, NBIS, MPWR, AEP, TER, UMC, ALAB, LMT, NOK, COHR, D, HON, CIEN, CRWV, VST, CBRS, CLS, ECL, AMT, CMI, CRDO, NOC, BIDU, TEL, NXPI, MDB, SMCI, NVT, GFS, SYM, ROK, ENTG, TSEM, NRG, STM, MTSI, LHX, RKLB, MCHP, NTNX, MKSI, LSCC, SMTC, FN, IREN, TLN, ONTO, ON, AMKR, NVMI, TEM, RMBS, FORM, ESTC, AAOI, APLD, WIT, CAMT, GDS, AAON, BWXT, AXTI, VIAV, UCTT, OKLO, VECO, AEHR, CRUS, MTRN, PDFS

Frontier (15): AUR, ASTS, IONQ, CGNX, XPEV, QNT, PL, GSAT, VSAT, OUST, PONY, RGTI, HSAI, IRDM, KRMN

Sources

Our scoreboard

• Silicon Sideline AI Economy Index, 2 Nov 2026 session, published scoreboard: siliconsideline.com/ai-index
• Reuters via CNA, 30 Oct 2026, week ahead: channelnewsasia.com

Definitions and history

• SEC Investor.gov, 3 Nov 2026 (accessed), "Bear Market" glossary: investor.gov
• Fidelity Learning Center, 6 Apr 2026, "What is a market correction?": fidelity.com
• Swoopr, 17 Oct 2026, "The Dot-Com Bubble: A 78 Percent Fall and a 15-Year Recovery": getswoopr.com

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