Why it moved, October 22: Bloom Energy -13%, Coherent -13%, Lumentum -12%

On Thursday, October 22 the S&P 500 fell 1.2% and 336 of 502 member stocks finished higher. AI-infrastructure stocks fell 6.6% on average. Last year's 50 best performers fell 2.3% on average. These were the five biggest moves among S&P 500 stocks, and what was behind each.

The biggest S&P 500 moves, October 22

"vs usual day" compares the move with the stock's average daily move (up or down) over the past year. "Where it stands" is the distance from the 52-week high and the position against the 200-day average. Stocks with a one-day change over 60% (usually a spin-off or split) are left out.

What this means

• Bloom Energy (BE) fell 12.7% as Barron's reported “Bloom Energy Stock Drops Despite Strong Earnings”¹. That is about 2 times its usual daily move. It was not alone: electrical equipment stocks fell 4.6% on average (Vertiv -7.8%, Eaton -6.3%, Ametek -4.6%). It reported quarterly results; options had priced a move of about ±11%. It is part of the AI build-out trade, and the AI-infrastructure stocks Torvanta tracks fell 6.6% on average, the day Yahoo Finance reported “GE Vernova Sinks 11%, Vertiv 14%, Bloom Energy 15% in a Week as AI Power Stocks Slide”². It is one of the past year's 50 best S&P 500 performers (+139.5% this year), a group that sold off today as investors took profits.
• Coherent (COHR) fell 12.5%. That is about 3 times its usual daily move. It was not alone: electronic component stocks fell 7.8% on average (Corning -7.8%, Amphenol -7.7%). It is one of the past year's 50 best S&P 500 performers (+12.6% this year), part of the same profit-taking.
• Lumentum (LITE) fell 11.5% as Yahoo Finance reported “Optics Stocks Tumble as Tech Selloff Deepens Ahead of Earnings: Coherent Tumbles 12%, Applied…”³. That is about 2 times its usual daily move. It was not alone: networking stocks fell 2.2% on average (Ciena -10.6%, Arista Networks -6.8%, Motorola Solutions +2.2%). It is one of the past year's 50 best S&P 500 performers (+104.2% this year), part of the same profit-taking.
• Lam Research (LRCX) fell 11.5% after an analyst cut its price target⁴. That is about 4 times its usual daily move. It was not alone: chip-equipment stocks fell 9.3% on average (Teradyne -10.8%, Qnity Electronics -9.5%, KLA -9.0%), after Yahoo Finance reported “Applied Materials Sinks 7% on Lam’s Outlook: “A Bit Higher” Wasn’t Enough”⁵. It reported quarterly results. It is one of the past year's 50 best S&P 500 performers (+35.3% this year), part of the same profit-taking.
• Flex Ltd. (FLEX) fell 11.1%. That is about 4 times its usual daily move. It was not alone: electronic manufacturing services stocks fell 3.8% on average (Jabil -4.9%, TE Connectivity -2.7%).
• A big one-day move tells you what the market learned that day, not where the stock goes next: large moves partly reverse about as often as they continue.

Sources

1. Barron's, Oct 22, 2026: Bloom Energy Stock Drops Despite Strong Earnings
2. Yahoo Finance, Oct 22, 2026: GE Vernova Sinks 11%, Vertiv 14%, Bloom Energy 15% in a Week as AI Power Stocks Slide
3. Yahoo Finance, Oct 22, 2026: Optics Stocks Tumble as Tech Selloff Deepens Ahead of Earnings: Coherent Tumbles 12%, Applied Optoelectronics Drops 10%, Lumentum Falls 9%
4. Yahoo Finance, Oct 22, 2026: LRCX Stock Sinks As Analysts Trim Targets, See Supply Constraints – But Longer-Term Bull Case Remains
5. Yahoo Finance, Oct 22, 2026: Applied Materials Sinks 7% on Lam’s Outlook: “A Bit Higher” Wasn’t Enough

Prices from Torvanta's end-of-day data; filings from SEC EDGAR. News context is drawn from the coverage cited below and may not be the whole cause of a move. Research only, not investment advice or a recommendation to buy or sell any security. Rankings change as data changes and can be wrong. Torvanta and its founder may hold positions in securities discussed, and trade only after the information is published to all subscribers. Past performance does not guarantee future results.

More research

• Insider & Short-Selling Daily, October 22 2026-10-22
• Market brief, October 22: S&P 500 falls 1.2% as chip-equipment stocks slide 2026-10-22
• Fair Value Check: Apple is overvalued on our numbers 2026-10-22
• The Giants Monitor: the top 10 are 42.5% of the S&P 500 (week of October 19) 2026-10-22
• Insider & Short-Selling Daily, October 21 2026-10-21
• Market brief, October 21: S&P 500 rises 0.5% as computer hardware stocks rally 2026-10-21
• Why it moved, October 21: Supermicro +9%, Charles River Laboratories +9%, Bloom Energy +9% 2026-10-21
• Midweek Movers: where the model's view shifted this week 2026-10-21
• Insider & Short-Selling Daily, October 20 2026-10-20
• Market brief, October 20: S&P 500 rises 0.3% as biotech stocks rally 2026-10-20
• Why it moved, October 20: Supermicro +13%, Equifax +11%, Hasbro +11% 2026-10-20
• Dividend Watch, October 20: Vici Properties leads covered yields 2026-10-20

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