Reason: Memory broke in the week to Friday, October 16. $WDC (down 16.43%) and $STX (down 18.39%) now sit 19.1% and 5.3% under their 200-days on years of +163.66% and +182.71%: long trends under test. $SNDK (down 17.86%), $SIMO (down 19.93%) and $MU (down 14.59%) still hold theirs, but the cushions shrank to 7.3%, 0.8% and 22.4% from 33.9%, 28.0% and 46.6% a week earlier. CNBC tied the lane's slide to China's CXMT memory progress and feared oversupply into 2029 (October 13 and 15), and reports of Toshiba expanding hard-drive output hit the drive makers; Friday's single-name moves have no cause on file.

Price/RSI Table

As of 2026-10-16. Status reads the 200-day trend first and RSI second; Action is a trend-hold lens: a pullback inside an intact trend is a flag to wait for, not an entry, and a name below its 200-day with a negative year is not a dip.

What Changed Since 2026-10-09

• STX: down 18.39% on the week (7.5% on Friday), RSI 27.6, now 5.3% under its 200-day ($674.45) from 18.0% above, 44.19% under its high, on a +182.71% year: a long trend under test. The October 15 market brief records its 3.19% fall that day on reports that Toshiba will expand hard-drive production and on pressure from CXMT (StockAnalysis; a media report, not a Toshiba release). Scheduled to report October 27 (provider date).
• WDC: down 16.43% (6.86% on Friday), RSI 27.0, 19.1% under its 200-day ($410.52) from 2.1% under, 58.49% under its high, on a +163.66% year. UBS cut its price target from $525 to $470 while keeping a Neutral rating, citing near-term hard-drive supply and competition (StockAnalysis summary, October 15). Listed to report October 22 (provider estimate).
• MU: down 14.59% (5.63% on Friday), RSI 34.0, 22.4% above its 200-day ($717.84) from 46.6% above, on a +333.93% year; it closed at $878.84, under both shelves the October 12–13 briefs named ($965.55 and $921.02). CNBC's October 15 piece on memory stocks "getting hammered" names China and a 2029 oversupply as the worries, and The Buildout relayed on October 12 an X post saying a German court issued a sales injunction against Micron NAND over a YMTC patent (single source). No dated Micron event is in the event files for the coming weeks.
• SNDK: down 17.86% (6.85% on Friday), RSI 29.7, 44.81% under its high but 7.3% above its 200-day ($1,210.71) on a +800.6% year: the cushion was 33.9% a week ago. Listed to report October 29 (provider estimate).
• SIMO: down 19.93% to RSI 29.9, 0.8% above its 200-day ($209.68) on a +128.78% year, from 28.0% above. A 6-K filed October 16 is on file, contents unread; news was last pulled September 15, so not pulled for this move. Report listed October 28 (provider estimate; an October 29 entry was superseded).
• Group read: the October 13 market brief had memory 0 of 10 up and CNBC tied the chip rout to reports that China's CXMT has made progress on new memory designs; the October 15 brief had memory 2 of 10 up. The AI scan has the semiconductor fund down 10.53% on the week. The memory-supercycle and nearline-storage campaign frames were last refreshed September 6, before this week's break. Roster unchanged since October 9.

Watch

The 200-days are the lines: STX $674.45 and WDC $410.52 to reclaim, SNDK $1,210.71, SIMO $209.68 and MU $717.84 to hold. The dated tests are the drive makers' reports (Western Digital October 22, Seagate October 27) and Sandisk (October 29), all provider dates.

Sources

• Tape data (price, RSI, returns, one-year change, distance to the 200-day): pre-computed summaries as of the 2026-10-16 settled close, summaries (Massive/Polygon; Schwab for WDC).
• Prior edition (format and roster only): 2026-10-09-memory; campaign refresh dates from ACTIVE.
• Event checks: research/stock-events/ (Western Digital October 22, Seagate October 27, Silicon Motion October 28, Sandisk October 29; superseded entries ignored), the 2026-10-12 through 2026-10-15 market briefs under research/issues/, research/capture/ for October 12–16 (Silicon Motion 6-K stub of October 16; Micron Form 4 filings of October 15); news receipts under stocks/news/latest.json` (MU, STX, WDC and SNDK pulled 2026-10-16; SIMO 2026-09-15).
• Primary links: CNBC, Micron, Seagate, Western Digital sink as chip sell-off deepens, October 13 — https://www.cnbc.com/2026/10/13/sk-hynix-softbank-samsung-electronics-shares-tech-stocks-fall.html; CNBC, Memory stocks are getting hammered, October 15 — https://www.cnbc.com/2026/10/15/memory-stocks-micron-sk-hynix-samsung-china.html; StockAnalysis, Seagate and Western Digital overview pages (aggregator) — https://stockanalysis.com/stocks/stx/ and https://stockanalysis.com/stocks/wdc/; The Buildout, German court Micron NAND injunction (relayed X post) — https://x.com/mindmoon_108/status/2109570507972784227.