The S&P 500 rose 0.41% on Monday 19 October, which left it 1.49% lower over the five sessions since the 12 October close. Weekly figures below use that baseline. Most names in the sell-off bounced on lighter volume, and nearly all of the weekly losses had no company news behind them. Hot September CPI and worries about financing AI build-outs remain the common explanation.
Optics, Chip Equipment and Power Infrastructure
This is the third week of the slide in optical and chip names, and today's weekly numbers are a continuation. COHR (-19.44% wk) closed at $232.02 after a flat Monday (-0.38%). AMAT (-16.97% wk) closed at $413.11 after a 0.93% rebound. LITE (-16.16% wk) rose 1.26% to $834.51, its first gain since 9 October. CIEN (-15.01% wk) added 3.45% to $344.20 on 1.14x average volume.
The one company-linked trigger is at Applied Materials, where management declined to give a wafer fab equipment outlook at its 13 October investor day. Analysts cut targets there while consensus 2027 earnings estimates rose. The optical names have no company news, and their order books remain strong, with Lumentum's capacity booked into 2029.
The power and cooling names fell in line. VRT (-13.90% wk) closed at $206.08 after RBC, Mizuho and Morgan Stanley trimmed targets and kept positive ratings. BE (-13.75% wk) rose 2.22% to $226.22 ahead of Thursday's results, where options imply a move of about 9%.
Server and Storage Hardware After Barclays
The 14 October Barclays downgrades keep working through the group. DELL (-21.03% wk) closed at $455.44 and HPE (-20.56% wk) at $55.87, with Barclays arguing that memory pricing explains more of their revenue growth than enterprise AI demand does. NTAP (-13.30% wk) closed at $207.37 and still sits 96.80% higher this year. Dell is up 259.63% over the same span, so the drop has taken a fifth off a very large rally.
SMCI (-19.71% wk) closed at $32.10, after the contractor's guilty plea in the Nvidia-server export case and a CFO change, with the 16 October fall of 9.86% the steepest session. P (-18.17% wk) closed at $127.09 after a 2.48% bounce on Monday, and no sourced driver explains its last two sessions. All five rose on Monday, between 0.83% and 2.48%.
Memory and Storage Rebound
Memory and storage ended a losing run with the day's strongest gains. SNDK (+5.53%) closed at $1,371.12 on 0.79x average volume, and WDC (+6.09%) at $352.21 after Friday's 6.86% fall. The reports give no company cause for either. Sandisk remains 22.39% below its 21 September close, and Western Digital still carries the Toshiba capacity story, a Wells Fargo target cut and a CFO departure.
Software and Cybersecurity
Cybersecurity and infrastructure software, which joined the slide on 16 October, show a split. DDOG (+5.36%) closed at $260.36 after Bernstein upgraded it to Outperform with a $350 target, citing alternative data on AI lab token consumption. TWLO (+5.29%) recovered part of Friday's 10.62% drop as yields eased, and it sits 8.98% under its 12 October close.
The weekly losers recovered less. CRWD (-13.27% wk) rose 0.31% to $228.10, and PANW (-14.09% wk) rose 1.45% to $346.95. The Palo Alto PAN-OS flaw and the report of OpenAI talks to buy Trail of Bits hit both names, and sources disagree about what drove Palo Alto on 16 October. AKAM (-14.17% wk) closed at $87.25 with no company-specific cause, and investors still question how it will fund its Anthropic-related build-out.
Spin-Off and Warrant Stories
FLEX (-25.33% wk) closed at $87.54, the largest weekly fall of the group. The first leg on 13 October followed concern over financing for the Axiom spin-off, including a $2bn convertible preferred issue that Flex guarantees. The last two sessions have no sourced explanation.
SKYD (-25.76% wk) closed at $6.80. Almost all of the loss came on 14 October, when 470,746,773 warrants went ex-dividend. Bernstein then cut its target to $6 on leverage, with pro forma net debt of $78.9bn.
What to watch
- 22 October: Bloom Energy (BE) and Western Digital (WDC) report.
- 28 October: Flex (FLEX) and Vertiv (VRT) report.
- 29 October: Sandisk (SNDK) and Twilio (TWLO) report.
- 3 to 5 November: Super Micro (SMCI), Coherent (COHR), Datadog (DDOG), Lumentum (LITE) and Akamai (AKAM).
- 9 to 12 November: Skydance (SKYD), then Applied Materials (AMAT).
- 19 November: Palo Alto Networks (PANW) reports.
- 1 December: CrowdStrike (CRWD) reports.