The sector's deterioration broadened this week rather than concentrating in Dow, the name that confirmed a death cross two scans ago. Dow's own alpha flipped negative for the first time in this series (+4.48→-0.19), meaning it's now lagging the market on every horizon, not just structurally damaged short-term. PPG posted the sector's sharpest single-week decline (-6.25%), its RSI dropping from 47.0 to 34.4 and its one-year return flipping from +2.64% to -5.66%. Sherwin-Williams, Air Products, and Linde all crossed or deepened below their 200-day averages this week, each still carrying double-digit negative alpha. DuPont ($DD) remains the sector's clear long-term winner — up 29.77% over the year with the cohort's best alpha at +13.55 — even as its RSI dropped into oversold territory (29.2) on a further pullback below its 200-day. LyondellBasell ($LYB) is the steadiest name in the cohort, holding its "strong-up" trend tag and staying comfortably above its 200-day, though its alpha remains roughly flat versus the market.

Data as-of the 2026-09-11 close for all nine tickers, including the sector ETF ($XLB). All numbers from the pre-computed chemicals summary. Comparison scan: the September 4, 2026 close — a normal one-week gap.

Every name in the cohort eased on RSI this week except LyondellBasell, which held flat. Dow dropped from 42.0 to 40.2 and fell 2.06% on the day alone, still carrying its confirmed death cross from two scans ago. Air Products had the sharpest RSI drop in the sector (47.8→37.7), and DuPont's RSI fell into oversold territory for the first time this series (36.2→29.2). PPG's RSI dropped from 47.0 to 34.4 on the sector's worst weekly return (-6.25%, more than double the next-worst name), pushing it into the approaching-oversold band alongside DuPont. None of the sector's trend tags improved this scan; Ecolab's downgraded from strong-up to weak-down as its RSI eased from 47.2 to 45.3 and its 30-day return swung from -2.17% to +4.06% — still a mismatch between a constructive-sounding tag and a middling underlying number.

The 200-day check is where this week's real story sits. Sherwin-Williams flipped from 0.3% above its 200-day to 3.2% below it; Air Products eased from 7.5% above to 2.9% above (still positive but nearly half its prior cushion gone); Linde deepened from a fractional 0.6% breach to a full 3.2% below; PPG's breach deepened materially; and Dow, DuPont, and XLB all drifted further below or eased further from their 200-day lines than they were a week ago. Only LyondellBasell held its position (5.0%→4.6% above, essentially flat) and DuPont, despite its RSI hitting oversold, remains the sector's best on every long-run measure — up 29.77% over the year (was 35.94%) with the cohort's best alpha at +13.55 (was +17.29), both easing but still far ahead of the rest of the cohort. Dow's alpha crossing to negative (-0.19, was +4.48) is the sharpest single change in the cohort this scan — a name whose trailing year had stayed marginally ahead of the market even through its death cross now lags on every window, consistent with its weak 2-year (-42.78%) and 3-year (-45.91%) record. The sector ETF, XLB, also cooled — 4.7% above its 200-day two scans ago, now 1.4% above, RSI down to 39.1 from 49.5 — though it remains one of the few names in the cohort still net positive above its trend line.

Dow and LyondellBasell run the sector's largest petrochemical/olefins operations and are structurally the most exposed names in this cohort to crude-oil and natural-gas-liquids feedstock costs. Brent crude broke back above $100 a barrel this week (Bloomberg and CNBC, September 9, on continued US-Iran tanker strikes), and Bloomberg (September 9) tied the same spike to a broader Treasury-yield selloff — a real macro backdrop for rising input costs across the sector. But no company-specific news receipt for any of the nine names in this corpus falls inside the September 4–11 window (the freshest, Dow's, is dated August 28 and predates this move), and no stock-events entry sits in that window either — so the oil/feedstock-cost backdrop is documented macro context, not a confirmed driver of any single name's move this week. This lines up with the same oil-input exposure showing up in this week's airlines and cruise-line reads.

• Dow: RSI 42.0→40.2 (dropped), trend strong-down unchanged, death cross still confirmed, price $29.44→$29.03, 7D -3.54%→-1.39% (improved), 30D -0.78%→-5.04% (worsened), vs 200-day -6.5%→-8.2% (deepened), 1Y +23.13%→+16.03% (worsened materially), alpha +4.48→-0.19 (flipped negative — now lagging the market on every horizon).
• LyondellBasell: RSI 50.0→49.9 (flat), trend strong-up unchanged, price $63.52→$63.69 (roughly flat), 7D -0.24%→+0.27%, 30D +7.61%→+1.42% (decelerated), vs 200-day +5.0%→+4.6% (roughly flat), 1Y +16.98%→+14.82% (eased), alpha -1.4 (roughly flat vs -1.67) — the steadiest name in the cohort.
• Sherwin-Williams: RSI 41.8→37.9 (dropped), trend down→weak-down (downgraded), price $333.71→$323.31, 7D -3.23%→-3.12% (roughly flat), 30D -9.52%→-10.24% (worsened), vs 200-day +0.3%→-3.2% (flipped negative), 1Y -8.77%→-12.31% (worsened), alpha -27.42→-28.52 (worsened, sector's worst).
• Air Products: RSI 47.8→37.7 (dropped sharply), trend weak-down unchanged, price $301.27→$291.43, 7D -2.21%→-3.27% (worsened), 30D +2.09%→-4.16% (turned negative), vs 200-day +7.5%→+2.9% (eased notably), 1Y +3.9%→-1.05% (flipped negative), alpha -14.75→-17.27 (worsened).
• Linde: RSI 38.5→34.5 (dropped), trend down unchanged, price $477.57→$466.22, 7D -2.46%→-2.38% (flat), 30D -2.75%→-2.76% (flat), vs 200-day -0.6%→-3.2% (deepened), 1Y +1.1%→-3.59% (flipped negative), alpha -17.55→-19.81 (worsened).
• Ecolab: RSI 47.2→45.3 (roughly flat), trend strong-up→weak-down (downgraded), price $279.28→$276.18, 7D -2.61%→-1.11% (improved), 30D -2.17%→+4.06% (swung positive), 1Y +1.58%→+0.47% (eased), alpha -17.07→-15.75 (slightly improved).
• PPG: RSI 47.0→34.4 (dropped sharply into approaching-oversold), trend down unchanged, price $112.53→$105.50, 7D -1.44%→-6.25% (the sector's sharpest weekly move), 30D -5.54%→-7.94% (worsened), 1Y +2.64%→-5.66% (flipped negative), alpha -16.02→-21.88 (worsened).
• DuPont: RSI 36.2→29.2 (dropped into oversold), trend down unchanged, price $131.59→$126.99, 7D -3.86%→-3.5% (roughly flat), 30D -10.71%→-12.04% (worsened), vs 200-day -3.7%→-7.3% (deepened), 1Y +35.94%→+29.77% (eased but still by far the sector's best), alpha +17.29→+13.55 (eased but remains the sector's best by a wide margin).
• XLB (ETF): RSI 49.5→39.1 (dropped), trend weak-down unchanged, price $52.44→$50.95, 7D -1.35%→-2.84% (worsened), 30D -0.38%→-3.10% (worsened), vs 200-day +4.7%→+1.4% (eased significantly), 1Y +14.85%→+10.02% (eased), still one of the few names in the cohort net positive above its 200-day.

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, and a "strong-up" tag can sit on top of a year that's actually lagging the market. 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: a name above its 200-day with a strong one-year gain and positive alpha is genuinely beating the market; a name that's flat-to-negative on the year with meaningfully negative alpha is quietly lagging no matter how constructive its short trend tag looks, and this scan several names (Sherwin-Williams, Air Products, Linde) crossed from the first camp into the second.

RSI < 25 (Oversold): None this scan.

RSI 25-40 (Approaching Oversold): DuPont (29.2), Linde (34.5), and PPG (34.4) sit here. DuPont's read is still the sector's best on the year despite the low RSI — a deep pullback in an intact trend. Linde and PPG are genuinely weak — both flipped to negative one-year returns with double-digit negative alpha this scan.

RSI 40+ (Neutral-to-Strong): The remaining six names sit here, but the multi-year check splits them sharply. Dow (40.2) confirmed alpha lagging the market for the first time this series. LyondellBasell (49.9) and XLB (39.1, technically in the band below but closest to it) both hold above their 200-days with solid one-year gains, though alpha stays roughly flat. Sherwin-Williams (37.9), Air Products (37.7), and Ecolab (45.3) all newly carry flat-to-negative one-year returns with meaningfully negative alpha — the sector's laggard cluster, now larger than two scans ago.

Does Dow's negative alpha flip prove temporary, or does it confirm the deeper multi-year decline the 2-3 year numbers already show? Does the deterioration that spread to Sherwin-Williams, Air Products, and Linde this week keep widening, or was this a one-week air pocket? And does DuPont's oversold RSI resolve as a buying opportunity inside its still-intact best-in-sector trend, or does the pullback deepen further below its 200-day.

• Tape data (price/RSI/SMA/returns/alpha/200-day): pre-computed summaries as of the 2026-09-11 close — chemicals.
• Comparison figures: 2026-09-04-chemicals (2026-09-04 close).
• Broad-market context (SPY, TLT, VIXY): market-pulse (same 2026-09-11 close).
• Cross-sector read: airlines, travel-leisure (same close).
• Oil/rate macro corpus: 2026-09-09-bloomberg-oil-tops-100-on-supply-fears-apple-faces-a-big-test-tl3y1mn3n0bb00, 2026-09-09-cnbc-brent-crude-nears-100-a-barrel-as-u-s-iran-tit-for-tat-strik-108360126, 2026-09-09-bloomberg-stocks-bonds-drop-as-oil-spike-boosts-fed-wagers-markets-wra-tl47jjkijh8t00.
• News/event check per ticker: stocks{DOW,LYB,SHW,APD,LIN,ECL,PPG,DD,XLB}/news/latest.json— all nine predate or fail to cover the September 4–11 window (Dow freshest at August 28; PPG and XLB pulls marked stale/failed);research/stock-events/` has no entry for any of the nine tickers in this window — driver unconfirmed at the ticker level from this data.