This is the week the chemicals cohort went fully below the line. The sector ETF ($XLB) crossed from 1.4% above its 200-day to 0.8% below it, and seven of the nine names now trade under that average — only LyondellBasell ($LYB, +1.0%) and Air Products ($APD, +0.1%) are above, and both cushions are nearly gone. All nine closed below their 20-day averages. The two most feedstock-exposed names took the worst single day: Dow ($DOW) fell 2.58% Friday and LyondellBasell 3.61%, the two biggest one-day declines in the cohort, in a week when US diesel hit record highs and Yahoo Finance reported (September 14) that Dow is rethinking its $20 billion Saudi chemicals bet. The one improvement is DuPont ($DD), which bounced out of oversold — RSI 29.2 to 40.5, +1.59% on the week — and holds the cohort's only strong long-horizon record: up 31.64% over the year with alpha of +16.63. Everything else is a cohort compressed into a narrow, weak RSI band with no leadership left.

Data as-of the 2026-09-18 close for all nine tickers, including the sector ETF ($XLB). All numbers from the pre-computed chemicals summary. Comparison scan: the September 11, 2026 close — a normal one-week gap.

The whole cohort now trades below its 20-day average, and the spread is wide: Air Products 4.9% under, PPG 4.6%, Dow 4.5%, XLB 3.9%, LyondellBasell 3.7%, Sherwin-Williams and Ecolab 3.5%, Linde 3.3%, DuPont 2.2%. RSI compressed into a narrow weak band — Linde 32.4, Air Products 33.5, PPG 33.5, XLB 35.4, Ecolab 36.4, Sherwin-Williams 36.5, Dow 40.3, DuPont 40.5, LyondellBasell 43.9 — which is the signature of a sector selling as one rather than a few broken names dragging an average.

The 200-day check is where the week's damage confirms. The sector ETF crossed from 1.4% above to 0.8% below, so the broad instrument no longer sits on the right side of its own trend. Air Products' cushion, already halved last week from 7.5% to 2.9%, is down to 0.1% — effectively on the line. LyondellBasell's fell from 4.6% above to 1.0% above. Below the line, Dow deepened from 8.2% to 9.6% under, PPG to 6.5%, DuPont to 6.0%, Linde from 3.2% to 4.7%, Sherwin-Williams from 3.2% to 3.8%, and Ecolab sits 1.3% under. That is seven of nine below, with the remaining two within a point of joining them.

Feedstock, not demand, is this sector's oil channel — Dow and LyondellBasell run the cohort's largest petrochemical and olefins operations and buy crude and natural-gas-liquids inputs directly — and those two took the cohort's worst Friday: Dow -2.58% and LyondellBasell -3.61%, against a broad index that was roughly flat (-0.12%). The week's energy backdrop is documented: US diesel hit record highs Tuesday as stockpiles ran low (Semafor, September 15), US oil topped $105 after Saudi Arabia closed its East-West pipeline and cancelled cargoes (CNBC, September 14 and 15), and prices eased only late in the week as ship-to-ship transfers were offered (CNBC, September 17). Dow is the one name with a company-specific item on the wire inside this window: Yahoo Finance reported September 14 that the company is rethinking its $20 billion Saudi chemicals bet. Dow's own news pull completed September 17 and returned only overview and quote pages — nothing naming a Friday event — so treat the Saudi item as documented context for the name, not a confirmed cause of Friday's 2.58% decline. The Fed raised its main rate a quarter point Wednesday citing stubborn inflation (Yahoo Finance and CNBC, September 16), its first hike in three years, which lifts the financing cost of a capital-heavy sector; no receipt in this corpus ties that decision to any individual name's move here.

DuPont is the exception worth naming precisely. Its RSI rose from 29.2 to 40.5, it gained 1.59% on the week while the other eight all fell, and its one-year return improved to 31.64% with alpha at +16.63 — the only genuinely market-beating record in the cohort, and more than double the next best. But it is still 6.0% below its own 200-day, down 9.87% over three months, and it now carries a death cross — so this is a bounce inside a name whose long record is strong and whose intermediate trend is not yet repaired.

• Dow: RSI 40.2→40.3 (flat), trend strong-down unchanged, death cross still confirmed, price $29.03→$28.73, 1D -2.58% (the cohort's second-worst day), 7D -1.39%→-1.03% (roughly flat), 30D -5.04%→-9.51% (worsened), vs 200-day -8.2%→-9.6% (deepened, cohort's widest breach), 1Y +16.03%→+19.16% (improved), alpha -0.19→+4.15 (flipped back positive after last scan's flip negative).
• LyondellBasell: RSI 49.9→43.9 (dropped), trend strong-up→weak-down (downgraded), price $63.69→$61.93, 1D -3.61% (the cohort's worst day), 7D +0.27%→-2.76% (turned negative), 30D +1.42%→-6.25% (turned negative), vs 200-day +4.6%→+1.0% (cushion nearly gone), 1Y +14.82%→+17.54% (improved), alpha -1.4→+2.52 (flipped positive).
• Sherwin-Williams: RSI 37.9→36.5 (eased), trend weak-down→down, price $323.31→$320.73, 7D -3.12%→-0.8% (improved), 30D -10.24%→-9.29% (roughly flat), vs 200-day -3.2%→-3.8% (deepened), 1Y -12.31%→-8.25% (improved from a negative base), alpha -28.52→-23.26 (improved but still the cohort's worst).
• Air Products: RSI 37.7→33.5 (dropped), trend weak-down unchanged, price $291.43→$284.18, 7D -3.27%→-2.49% (still negative), 30D -4.16%→-6.28% (worsened), vs 200-day +2.9%→+0.1% (cushion effectively gone — on the line), 1Y -1.05%→-2.83% (worsened), alpha -17.27→-17.84 (roughly flat).
• Linde: RSI 34.5→32.4 (dropped, cohort's lowest), trend down unchanged, price $466.22→$460.40, 7D -2.38%→-1.25% (improved), 30D -2.76%→-4.31% (worsened), vs 200-day -3.2%→-4.7% (deepened), 1Y -3.59%→-3.28% (flat), alpha -19.81→-18.29 (roughly flat).
• Ecolab: RSI 45.3→36.4 (dropped sharply), trend weak-down→down, price $276.18→$269.46, 7D -1.11%→-2.43% (worsened), 30D +4.06%→-5.66% (swung negative), vs 200-day now -1.3%, 1Y +0.47%→+1.75% (flat), alpha -15.75→-13.27 (improved slightly).
• PPG: RSI 34.4→33.5 (eased), trend down unchanged, price $105.50→$104.52, 7D -6.25%→-0.93% (improved sharply after last scan's worst-in-sector week), 30D -7.94%→-8.25% (flat), vs 200-day now -6.5%, 1Y -5.66%→-4.13% (roughly flat), alpha -21.88→-19.14 (improved slightly, still deeply negative).
• DuPont: RSI 29.2→40.5 (bounced out of oversold), trend down→strong-down (the short tag downgraded even as price rose), price $126.99→$129.01, 7D -3.5%→+1.59% (the cohort's best week), 30D -12.04%→-7.64% (improved), vs 200-day -7.3%→-6.0% (narrowed), 1Y +29.77%→+31.64% (improved, cohort's best), alpha +13.55→+16.63 (improved, cohort's best by a wide margin).
• XLB (ETF): RSI 39.1→35.4 (dropped), trend weak-down→down, price $50.95→$49.99, 7D -2.84%→-1.88% (improved), 30D -3.10%→-4.82% (worsened), vs 200-day +1.4%→-0.8% (flipped negative — the sector instrument lost its trend line this scan), 1Y +10.02%→+10.01% (flat), alpha -5.0.

RSI (Relative Strength Index) gauges how aggressively a stock has been bought or sold over roughly the past two weeks, on a 0-100 scale — under 30 signals an oversold, potentially undervalued stretch; over 70 signals overbought, extended risk; readings in between are neutral. Trend reflects a stock's structural direction based on its moving averages over the past several weeks — it is a short-window read, not a verdict on the multi-year story, which is why DuPont can carry the sector's best one-year record and its weakest short trend tag in the same row. vs SMA shows how far price sits above or below its 20-day average. The one-year change, alpha and distance from the 200-day average are the longer-horizon check, and this scan they say something blunt: seven of nine names are below their 200-day, six of nine carry negative alpha, and only DuPont has both an intact long record and a positive alpha worth calling a trend. Note that several alpha readings improved this week while prices fell — the broad index's own one-year window moved too, so read the level, not the direction. Nothing here is a setup; these are screen conditions.

Capitulation, RSI under 25: None this scan.

Oversold, RSI 25-40: Linde (32.4), Air Products (33.5), PPG (33.5), XLB (35.4), Ecolab (36.4) and Sherwin-Williams (36.5) — six of the nine, the widest oversold cluster this series has shown. None of them has a long-horizon record that turns a low RSI into an opportunity: all six carry negative alpha, five are below their 200-day and the sixth (Air Products) is on it. This is a sector being sold, not a set of individually stretched names.

Neutral to strong, RSI 40+: Dow (40.3), DuPont (40.5) and LyondellBasell (43.9). Only DuPont's is backed by a long record worth the name — up 31.64% on the year with +16.63 alpha. Dow's one-year return improved to +19.16% and its alpha flipped back positive at +4.15, but it holds the cohort's widest 200-day breach and a -44.36% two-year record. LyondellBasell's trend tag was downgraded from strong-up to weak-down this week and its 200-day cushion is down to a single point.

Does Air Products hold the 200-day it is now sitting on, or does the cohort go eight-of-nine below the line? Does LyondellBasell's remaining one-point cushion survive another week of feedstock cost pressure? Does XLB's cross below its 200-day confirm, which would make this a sector-level trend break rather than a collection of single-name breakdowns? And does DuPont's bounce carry far enough to reclaim the 6.0% sitting between it and its own 200-day, or does the cohort's only intact long record get pulled under with the rest?

• Tape data (price/RSI/SMA/returns/alpha/200-day/2-year/3-month): pre-computed summaries as of the 2026-09-18 close — chemicals.
• Comparison figures: 2026-09-11-chemicals (2026-09-11 close).
• Broad-market context (SPY, USO, XLB): market-pulse (same 2026-09-18 close).
• Cross-sector read: airlines, travel-leisure (same close).
• Energy, policy and company corpus: 2026-09-15-semafor-us-diesel-hits-record-highs-as-oil-supply-fears-mount-pply-fears-mount, 2026-09-14-cnbc-oil-prices-rise-after-saudi-arabia-shuts-down-critical-pipel-108362194, 2026-09-15-cnbc-u-s-oil-tops-105-as-saudi-arabia-reportedly-cancels-some-cru-108362801, 2026-09-17-cnbc-oil-extends-losses-as-saudi-arabia-reportedly-offers-ship-to-108364169, 2026-09-14-yahoofinance-dow-rethinks-its-20-billion-saudi-chemicals-bet-i-144104986-html, 2026-09-16-yahoofinance-fed-hikes-main-interest-rate-by-quarter-point-citing-stubbor-e-135731525-html, 2026-09-16-cnbc-fed-delivers-its-first-hike-in-3-years-plus-what-s-moving-st-108363844.
• News/event check per ticker: stocks{DOW,LYB,SHW,APD,LIN,ECL,PPG,DD,XLB}/news/latest.json— only Dow's (September 17) and DuPont's (September 11) pulls are current, and Dow's returned overview and quote pages with no Friday event; PPG's and XLB's are marked failed and stale (June 21 and April 29), which is not evidence of no news.research/stock-events/` has no entry for any of the nine in the September 11–18 window. Drivers unestablished at the ticker level from this data.