Micron stock closed at $989.04, down 3.88%, bull $1,761,…

The lazy reading of Tuesday’s Micron tape is that Seoul sold memory and New York has not had its turn. It has. Nasdaq’s historical file shows Micron Technology closed Monday, 12 October 2026, at $989.04, down $39.96, or 3.88%, from Friday’s $1,029.00. The Philadelphia Semiconductor Index, the SOX, closed at 12,236.79, down 335.63 points, or 2.67%. The Nasdaq Composite fell 0.44%, to 27,245.90. Monday was a memory session, not a broad Nasdaq break.

The missing clock is Tuesday morning. At 7:51 a.m. Eastern, Nasdaq’s quote page still had the shares in premarket at $951.40, down another $37.64, or 3.81%, and $27.10 under Monday’s low of $978.50. The regular session had not opened. That print is not a daily close, and it is not a bar on the chart. Monday’s Composite open was 27,352.51, about 0.05% under Friday’s close, so a 0.4% “open” is not this tape. The Korea follow-through is a second leg, still waiting on a cash print. Monday’s SOX decline is already a finished move.

Key facts

• Monday 12 October 2026 regular-session close $989.04, down $39.96, or 3.88%, from Friday’s $1,029.00. Open $1,002.445, high $1,002.67, low $978.50, volume 23,983,750. Source: Nasdaq historical prices for MU, downloaded 13 October 2026.
• SOX Monday close 12,236.79, down 2.67% from 12,572.42. Nasdaq Composite 27,245.90, down 0.44% from 27,366.17. Source: Nasdaq history for SOX and COMP.
• Tuesday 13 October, 7:51 a.m. Eastern, premarket last $951.40, down 3.81%, bid $951.40 and ask $951.54, market status premarket. That last was $27.10 under Monday’s low. Not a close. Source: Nasdaq’s MU quote page.
• Fiscal Q4 2026 revenue $54.229 billion, non-GAAP diluted EPS $33.42. Fiscal Q1 2027 guide: revenue $61.5 billion plus or minus $1.5 billion, non-GAAP gross margin about 86.25%. Source: Exhibit 99.1 to the 30 September 2026 Form 8-K.
• Same exhibit: cash, marketable investments, and restricted cash of $73.48 billion. Dividend $0.15, payable 29 October to holders of record on 14 October. Cloud Memory revenue $16.283 billion and Core Data Center $18.002 billion.
• Tuesday’s Korea close, as FinanceFeeds reported citing Naver Finance: Samsung 232,000 won, down 7.39%. SK hynix 1,443,000 won, down 10.09%. KOSPI 6,035.35, down 5.46%. This article did not re-download Naver.
• Nasdaq’s summary feed displayed a one-year target of $1,500. That is not the bull case below. The file’s intraday high is $1,255.00 on 25 June 2026, when the close was $1,213.56.
• SEC submissions for CIK 0000723125 show a Form 10-K on 9 October and no Form 8-K after 30 September.

What just happened, and why the obvious reading is wrong

Monday did not open at Friday’s close and drift. Micron opened at $1,002.445, already 2.58% under $1,029.00. The high was $1,002.67, 22 cents above that open. The low was $978.50, 4.91% under Friday. The close sat $13.41 under the open and $10.54 above the low. The session sold from the open. Volume was 23,983,750 shares, 20.4% above Friday and about 88.5% of the 27,087,010 average on Nasdaq’s summary feed. The 25 June day traded 83,040,960 shares. This was not a volume climax.

Nor was it day one. From the 7 October close of $1,088.00, Monday was down 9.10% across three sessions. The SOX fell from a 6 October close of 13,217.82 to Monday’s 12,236.79, down 7.42%. Thursday 8 October alone took the SOX from 13,066.15 to 12,623.71, down 3.39%. FinanceFeeds’ Nvidia note on that Thursday is a different catalyst inside the same week.

The split inside Monday is the other correction. SanDisk fell 5.97%, Intel 3.20%, Broadcom 1.88%, Nvidia 1.29%, and the VanEck Semiconductor ETF, SMH, 2.05%. SBS matched the Micron, Intel, Broadcom, and SOX percentages and said SK hynix’s US depositary receipts fell 4.02%, the Dow rose 0.38%, and the S&P 500 fell 0.06%. Memory did the work. The Composite did not.

Who is exposed

Micron is a Nasdaq-100 name on the quote page saved Tuesday morning. The SOX and SMH are the listed wrappers. SanDisk’s larger drop is the NAND print in the same file. FinanceFeeds’ SanDisk note is the NAND companion, not Monday’s tape.

The customers are in the 30 September exhibit. Cloud Memory did $16.283 billion of fiscal Q4 revenue and Core Data Center did $18.002 billion. Together that is $34.285 billion, 63.2% of the $54.229 billion quarter. Mobile and Client was $13.114 billion, 24.2%. Automotive and Embedded was $6.824 billion, 12.6%. Holders are long a data-center memory supplier first. Samsung and SK hynix are the competitors.

From the 31 December 2025 close of $285.41, Monday’s $989.04 is up 246.5%. From 1 October 2025, at $182.15, it is up 443%. From the 25 June 2026 close of $1,213.56 it is down 18.5%. A December holder is not in a drawdown. A June holder is. The book at risk chased the high.

What the tape shows

The rows are the Nasdaq daily file saved for this article. Change is versus the prior close in that file. Nothing here is a Tuesday print.

Monday’s cross-section, same files:

The 30 September close, the day of the earnings release, was $1,065.11. The next session closed at $1,097.39. Monday is 7.1% under the release-day close. The record quarter did not stop the give-back, and a two-week-old release did not cause Monday by itself.

What Micron has said, and what it has not

“Micron delivered record fiscal 2026 results, and we expect an even stronger fiscal 2027,” said Sanjay Mehrotra, chairman and chief executive, in the 30 September exhibit. He added: “AI is becoming Super Intelligence (SI), and memory enhances this intelligence and the competitiveness of our customers’ platforms. We are increasing our investments in technology, products and manufacturing to help drive SI forward with our customers, and our Strategic Customer Agreements provide added confidence in the durability of Micron’s financial performance.” That is a supply-and-contract claim. It is not a comment on a Chinese cell design.

A 3.88% day does not rewrite the year. Full-year revenue was $133.188 billion, against $37.378 billion the year before. Fourth-quarter operating cash flow was $43.97 billion and adjusted free cash flow was $33.20 billion. Long-term debt was $4.688 billion at 3 September, against $14.017 billion a year earlier. Receivables were $36.197 billion and inventories $10.372 billion.

The guide is the live fundamental number. Revenue of $61.5 billion plus or minus $1.5 billion is a 13.4% step up from $54.229 billion at the midpoint. Non-GAAP gross margin of about 86.25% is 0.75 points under the 87.0% just reported. FinanceFeeds’ note on that print used a $1,540 bull and an $880 bear off a different spot. Those levels are not these. The margin dip was public on 30 September.

The company has not answered the CXMT headline in a filing. Submissions show no 8-K on 12 or 13 October. On X, @MicronTech’s posts from 6 October ran through 9 October and did not mention the selloff. One, on 8 October, said the company plans to invest up to $50 million to support the Genesis Mission graduate fellowship and national lab research. A fellowship is not a response to a memory-cell claim. Silence is not a denial. Monday’s tape had no new company number on it.

The Korea read-through, and what it is not

The China claim was already public before Monday’s US open. A 12 October Seoul Economic Daily report, as carried by NiftyTrader, said CXMT plans a server DDR5 registered module on a 4F2 cell before the end of 2026. FinanceFeeds, citing Investing.com via Yahoo Finance, reported that CXMT president Cao Kanyu said the company plans DDR5 RDIMM server modules on a 4F2 structure by the end of 2026, without detailed specifications or a launch date. Mainstream DRAM is a 6F2 cell. A 4F2 design is a density claim. A year-end plan is not a shipped, qualified module.

That clock is why Tuesday is only half the story. Monday’s US session could already trade the 12 October report. Tuesday’s Korea session was the larger local print, after a sell-side sidecar FinanceFeeds placed at 9:47 a.m. Seoul. SBS, at 9:17 a.m., had the KOSPI at 6,094.96, down 4.53%. That is not the close. KED Global later said the KOSPI ended down 5.5%. FinanceFeeds’ Naver-cited close is 6,035.35, down 5.46%. Saxo’s morning note had the index down 6.12% at 5,993.62. The wires disagree because the clocks disagree.

“The domestic stock market will likely see continued weakness in early trading due to the sluggishness of the semiconductor sector and foreign supply-demand burdens,” said Seo Sang-young, managing director at Mirae Asset Securities, in the SBS English story. He added that ChangXin Memory’s progress “does not immediately imply an increase in supply or a drop in memory prices.” SBS says the English was translated by AI and may contain errors, so this is the translation on the page, not a Korean transcript. His point matches the US file. The Korea close after that 9:17 a.m. snapshot did not deliver the bargain hunting he still thought likely.

Chey Tae-won, chairperson of SK Group, is on the other side of the same race. In an 11 October post he is quoted saying, “If Chinese companies or U.S. Micron expand faster, Korea’s market share will shrink,” and, “There is huge demand, but if we can’t expand plants, that’s the problem.” The same post has him saying “CXMT and YMTC are continuing to advance at a terrifying pace.” That is a capacity comment from before Tuesday’s crash, not evidence a module shipped. A Tuesday post citing TrendForce and Yicai put Micron at $951, down 3.8% premarket, next to this article’s $951.40, and said CXMT had disclosed no capacity, yield, wafer starts, or customer qualification.

A dividend, a holiday, and oil

The $0.15 dividend cannot explain a 3.88% day. Against Monday’s $989.04 it is 0.015% of the price. Nasdaq’s summary feed showed a 0.06% yield on a $0.60 annualized dividend. The decline is roughly 256 times the quarterly cash. The exhibit’s record date is 14 October, and the quote page listed an ex-dividend date of 14 October. SBS called Monday relatively quiet Columbus Day trading. The equity file does not show a closed session. Micron’s volume was above Friday’s.

Oil is the macro SBS numbered. Brent for December finished up 1.84% at $106.65, and WTI for November finished up 2.06% at $93.74, which SBS tied to Houthi attacks on Saudi Arabia. The same story said September CPI and PPI, plus a week of bank results, sat on the US calendar. Those can pressure a multiple. They do not turn a 4F2 plan into wafers. Saxo rounded Micron to about 4% and the SOX to 2.7%. The file is 3.88% and 2.67%.

Bull, base, and bear

These levels are not a street target and not a prior FinanceFeeds pair. They are a volatility band around Monday’s $989.04 close. Take the last 90 daily log-returns in the Nasdaq file, from the 3 June 2026 close of $1,079.57 through 12 October. The sample mean is -0.000973 a day. The sample standard deviation, using the n-minus-1 divisor, is 0.056273, or 5.627% a day. That width is why the band is wide.

Carry the path to 31 December 2026. Weekday sessions from 13 October through 31 December, dropping Thanksgiving Day on 26 November and Christmas Day on 25 December, come to 56. No other holiday was removed. The mean path is $936.58, rounded here to $937, 5.26% under the Monday close. One standard deviation either side is about $1,427 and $615. The bull and the bear use 1.5 standard deviations: $1,761.48 and $497.99 before rounding, $1,761 and $498 in the title, up 78.05% and down 49.65%. Drift is only slightly negative, which is why the base sits close to spot. Nasdaq’s displayed one-year target of $1,500, 51.7% above Monday, sits between the base and the bull and is not this calculation.

What happens next

Tuesday, 13 October 2026, after 4:00 p.m. Eastern, is the first cash close that can confirm or fade the Korea leg. The 7:51 a.m. last, $951.40, is under Monday’s low. If the official close finishes under $978.50, the break is a cash fact. If it gets back inside $978.50 to $1,002.67, the second leg failed and Monday remains the US move. A futures post at that same minute described Nasdaq futures as down 0.7% and rounded Micron to 4%. This article did not save a futures series. The quote page said $951.40, down 3.81%.

Wednesday, 14 October, is the dividend record date, and the date the quote page labeled ex-dividend. The cash is $0.15. A multi-percent print that day needs a memory or a macro cause. Bank results and the inflation prints SBS flagged can move the multiple. They are not a DRAM shipment.

Through 31 December 2026 the checkpoint is the band, $498 to $1,761, around a $937 mean path, and inside it the guide of $61.5 billion plus or minus $1.5 billion. A qualified CXMT server DDR5 module would give the bear side a fundamental companion. A year that ends with the same plan, and no yield or qualification, would leave Monday plus the Tuesday premarket as a headline gap in a stock still up 246.5% from December 2025. The guide, not the cell diagram, is what changes the base.

Frequently asked questions

Is Tuesday’s setup a Korea spillover, or is Monday’s SOX decline already the move?

Monday’s cash close was already the first US leg, and Tuesday’s 7:51 a.m. premarket print is a second leg the cash session had not confirmed. Micron closed Monday at $989.04, down 3.88%, and the SOX closed at 12,236.79, down 2.67%, while the Nasdaq Composite fell 0.44%. The premarket last of $951.40 was down another 3.81% and under Monday’s low. Korea explains the second leg. It does not make Monday disappear, and it is not yet a Tuesday close.

What did Micron stock do on Monday 12 October 2026?

It closed at $989.04, down $39.96, or 3.88%, from Friday’s $1,029.00, on 23,983,750 shares. The open was $1,002.445 and the high was $1,002.67, so the session sold from the open down to a $978.50 low. The close was $10.54 above that low. Volume was 20.4% above Friday and below the 27,087,010 average on Nasdaq’s summary feed. The day was a memory selloff, not a Composite break.

What was the Tuesday premarket print, and is it a close?

No. At 7:51 a.m. Eastern on 13 October, Nasdaq’s quote page showed a premarket last of $951.40, down $37.64, or 3.81%, from Monday’s close, with the market status still premarket. That last was $27.10 under Monday’s low. The regular session had not opened, so the figure is not an official open and not a daily bar. A later cash print replaces it only when the exchange has produced one.

Did CXMT ship a DRAM product that competes with Micron this week?

Not on the pages read here. The fetched accounts describe a plan for server DDR5 modules on a 4F2 cell by the end of 2026, attributed to CXMT president Cao Kanyu, without detailed specifications or a launch date. A 4F2 cell is a density claim against today’s 6F2 mainstream cell. An X post citing TrendForce said CXMT had not disclosed capacity, yield, wafer starts, or a customer qualification. A plan is not a shipment.

Where do the $1,761 bull and the $498 bear come from?

They are 1.5 sample standard deviations around the mean path of the last 90 daily log-returns, carried 56 weekday sessions to 31 December 2026, from Monday’s $989.04 close. The base on that mean path is $937. Daily volatility in the window was 5.627%, so the band is wide. Nasdaq’s displayed one-year target of $1,500 is a different number. This is not a reused FinanceFeeds pair, and it is not financial advice.

Does the $61.5 billion guide still sit behind the stock?

Yes. The 30 September exhibit guides fiscal Q1 2027 revenue to $61.5 billion plus or minus $1.5 billion, with non-GAAP gross margin about 86.25%, a 0.75 point dip from the 87.0% just reported. No later 8-K in the Tuesday morning submissions list changed that guide. Monday’s drop and Tuesday’s premarket print can change the multiple. They do not, by themselves, change the revenue range. The next cash close is the test of the multiple, not of the exhibit.

This is not financial advice.