SK hynix at 1,443,000 Won, Down 10.09%: Bull 2,334,000,…

CXMT did not ship a 4F2 DRAM on Tuesday, and the 1,456,000 won on Naver’s screen was not the 15:30 cash close. That saved object was an after-market session, and the last on it was stamped 20:00 KST. The regular-session close is 1,443,000 won, down 162,000 won, or 10.09 percent, from Monday’s 1,605,000, with an open of 1,538,000 and a low of 1,425,000. The KOSPI closed at 6,035.35, down 5.46 percent, after a low of 5,911.11. That low is 7.41 percent under Monday’s 6,384.24. It is not a close at 5,914. A sell-side sidecar hit at 9:47:58 a.m. after KOSPI 200 futures fell 5.08 percent. With Tuesday set at 1,443,000, the day was 1.53 standard deviations of the last 90 sessions. To 31 December 2026 that maths is a bull of 2,334,000 won, a base of 1,064,000 won and a bear of 631,000 won.

The cash-session loss uses 162,000 won, not the gap from the later screen. Listed shares are 730,492,365. Times 162,000 won, the loss is 118.340 trillion won. At Hana Bank’s posted 1,341.50 won per dollar at 20:51 KST, that is $88.21 billion. At the Korea Times dollar close of 1,345.1, it is $87.98 billion. A round $85 billion matches neither rate, so it stays out of the headline.

Key facts

• SK hynix (KRX: 000660) regular-session close, 13 October 2026: 1,443,000 won, down 162,000, or 10.09 percent, from 1,605,000. Open 1,538,000, high 1,554,000, low 1,425,000, volume 5,431,079. Source: stockanalysis.com, marked “At close: Oct 13, 2026”.
• Listed shares 730,492,365. Cash market value 1,054.100 trillion won. The day’s mark-to-market loss is 118.340 trillion won, or $88.21 billion at Hana Bank’s 1,341.50 rate at 20:51:44 KST, up 5.50 won or 0.41 percent. Source: the Naver share count and Hana Bank dollar-won.
• KOSPI close 6,035.35, down 5.46 percent from 6,384.24. Open 6,186.08, high 6,198.46, low 5,911.11. Cash value 28.452 trillion won. Breadth: 630 fell, 247 rose, 41 unchanged. Source: Naver KOSPI.
• Korea Times: foreigners sold a net 4.51 trillion won, institutions bought 1.69 trillion and retail bought 2.23 trillion. On SK hynix, Naver shows foreigners net sold 1,613,929 shares, institutions net bought 414,821 and individuals net bought 782,218. The foreign ratio fell to 49.19 percent from 49.41 percent.
• Sell-side sidecar at 9:47:58 a.m. after KOSPI 200 futures fell 5.08 percent, the first since 19 August. A 10:40 a.m. print had the index at 5,996.16 and SK hynix at 1.468 million won. Not the closes. Source: Park Shin-won, Seoul Economic Daily.
• CXMT chief executive Cao Kanyu, in Shanghai on 9 and 10 October, said vertical surround gate transistors had laid groundwork for a 4F2 cell and that server DDR5 RDIMMs would follow by year-end. A 4F2 cell can cut area about 33 percent versus 6F2. A plan, not a shipment. Source: Park Si-jin, Seoul Economic Daily, 18:05 KST.
• Samsung Electronics closed at 232,000 won, down 7.39 percent. Source: the same-day FinanceFeeds Samsung note. Its bull and bear are not used here. KOSDAQ closed at 837.03, down 1.43 percent.
• Bull 2,334,000 won, base 1,064,000 won, bear 631,000 won. Mean and sample standard deviation of 90 daily log-returns, 1 June through 13 October 2026, with Tuesday at 1,443,000, over 57 weekdays to 31 December. The count includes 25 December because no 2026 holiday file was saved.

What just happened, and why the obvious reading is wrong

The obvious reading of the index is that it closed down 7.4 percent near 5,914. The low, 5,911.11, is 7.41 percent under Monday. The close, 6,035.35, is 5.46 percent under Monday and 124.24 points, or 2.10 percent, off that low. WikiFX at 12:00 UTC put the intraday plunge at 7.4 percent, with Samsung down 7.7 percent and SK hynix down 8.8 percent. Those were scare prints, not the closes.

Session at 07:41 UTC had the index at 6,035.35, down 5.46 percent, SK hynix down 10.09 percent and Samsung down 7.39 percent. That stock pair is the cash close. The Korea Times and the same-day FinanceFeeds Samsung note use 1,443,000 won and 232,000 won. This note does not rewrite that piece and does not use its bull or its bear. The screen that disagreed was Naver’s after-market last, not those wires.

At 10:40 a.m. the stock was 1.468 million won and the index 5,996.16. The cash close, 1,443,000, is 18,000 won off the 1,425,000 low and still under that morning print, while the index close is above its 10:40 print. Tuesday’s log-return, -0.10640, is 1.53 standard deviations, against 2.41 on 13 July, when the close fell from 2,180,000 won to 1,845,000. Cao spoke on 9 and 10 October. Monday had already closed at 1,605,000.

Who is exposed

The line is 730,492,365 shares, worth 1,054.100 trillion won at the cash close. Foreigners’ ratio fell to 49.19 percent from 49.41. Their net sale of 1,613,929 shares, valued at 1,443,000 won, is 2.329 trillion won, about $1.74 billion at 1,341.50. That is not the $88.21 billion mark, which is every share times 162,000 won. Individuals net bought 782,218 shares and institutions 414,821. Across 6, 7, 8, 12 and 13 October, foreign net sales add to 4,317,956 shares.

Regular-session value was 7.982 trillion won, 28.1 percent of the KOSPI’s 28.452 trillion. The chart uses daily closes, with Tuesday set at the 15:30 print. Samsung finished at 232,000 won, down 7.39 percent, while KOSDAQ fell 1.43 percent. The Seoul Economic Daily says CXMT is a latecomer in high-bandwidth memory for Nvidia’s accelerators. A server DDR5 plan is not that product. See the Micron shortage note.

What the tape actually shows

The scenario maths uses only the 1,443,000 won cash close. The other rows are clocks, not substitutes.

From the 22 June close of 2,919,000 won, Tuesday is down 50.57 percent. The file’s high is 2,987,000 won on 25 June. From 15 April’s 1,136,000, Tuesday is still up 27.02 percent, and from 2 October’s 1,842,000 it is down 21.66 percent. ScalpingX at 08:12 UTC had the index close right, and the five-minute program pause. That part matches.

What the named companies and officials have said

“We expect there will still be a meaningful time gap between CXMT’s unveiling of a 4F2 product and its commercialization at profitable yields,” said Jing Zhewei, an analyst at Morningstar, as carried by the Seoul Economic Daily on Tuesday evening. The sentence before it matters as much. Leading memory makers and the equipment suppliers, he said, have described this transition in similar terms. He is not calling the cell impossible. He is separating an unveiling from a profitable yield.

Park Si-jin’s piece reports Cao Kanyu as told, not from a transcript fetched here. Cao, identified there as chief executive, said vertical surround gate transistors had dealt with current leakage and that CXMT would release server DDR5 RDIMMs on the design by year-end. The South China Morning Post, citing a company statement, has president Cao on the same year-end product. TrendForce, citing Yicai, puts the speech on 10 October and says Cao cited more than 300 published patent families. An unnamed CXMT official told the Seoul Economic Daily that a DDR5 RDIMM has to run 24 hours without transfer errors, and that picking it as the first 4F2 target means taking those barriers on. That is an ambition. The Korea Times says yields, qualification and shipments remain unconfirmed.

SK hynix has not answered on the page that would count. Its English newsroom, opened Tuesday, had no item dated 13 October. The newest posts were a 2 October ventures note and a 1 October Solidigm clarification. The Korea Times says the company outlined a 4F2 platform in Japan in June last year and has not given a mass-production date. The Seoul Economic Daily says Samsung is aiming at 2028 for sub-10-nanometer DRAM, so on announced timelines alone CXMT would be about two years ahead. The Korea Times says Samsung has a working die and has not officially set a date. A post on 11 October caught the same split: Wccftech’s headline began “CXMT To Leapfrog Samsung By ~2 Years,” while Yicai’s report “says something smaller.”

The Seoul Economic Daily, citing Counterpoint, says CXMT’s DRAM share rose to 10 percent in the second quarter from 4 percent a year earlier. That is commodity share, not a qualified server module, and it is not a wafer that shipped on Tuesday.

The sidecar, the buyback and the won

The microstructure is tighter than the chip claim. The Seoul Economic Daily times the sell-side sidecar at 9:47:58 a.m., on a 5.08 percent drop in KOSPI 200 futures, the first since 19 August. The Korea Herald, which flags AI translation help, gives the futures print: 955.02, down 51.20 from a base of 1,006.22, after more than a minute under the 5 percent line. Program sell orders paused for five minutes. That is not a halt of the cash stock. Papers disagree on whether this was the 26th or the 50th trigger of the year, so the count is not used.

“The key reason why foreign selling on a scale similar (to August and September) has now triggered a sharp market decline is the disappearance of the buffer provided by share buybacks,” said Lee Kyoung-min, an analyst at Daishin Securities, in the Korea Times. That story says foreigners sold a net 31.7 trillion won in August and September, the KOSPI still rose 3.7 percent, and the two buybacks absorbed about 1.61 trillion won a day. Samsung’s program has ended. SK hynix’s, the paper says, is set to end this week. Lee also said valuations imply a 35 to 51 percent earnings decline versus forecasts. The index forward multiple in the story is a record-low 4.54, which this note did not recompute.

Chosunbiz, in a machine-translated piece, puts Samsung’s buyback at 15 trillion won inside a 110 trillion return plan, finished on 6 October, and SK hynix’s at 40 trillion won, to be cancelled in full. Other corporations bought a net 49 trillion won from 20 August to 13 October. On the Korea Times telling, the hynix bid is almost over. Hana’s notice was 1,341.50. The Korea Times dollar close is 1,345.1. An earlier FinanceFeeds note already had the index through 7,000 after Chuseok. Tuesday’s 6,035.35 is 33.8 percent under the highest close in the KOSPI file saved here, 9,114.55.

Bull, base and bear, with the maths

The last 90 log-returns, 1 June through 13 October, use 1,443,000 won as Tuesday’s close. The mean is -0.00533812 a day. The sample standard deviation is 0.06932036. The drift is negative because the window includes the fall from June. The horizon is 31 December 2026, 57 weekdays from 14 October, including 25 December because no holiday file was saved.

One standard deviation over 57 sessions is 0.06932036 times the square root of 57, or 0.523357. One and a half is 0.785036. The drift is -0.304273. The bull adds them: 0.480763 in log terms, times 1,443,000 won, is 2,333,776 won. The base, drift alone, is 1,064,443 won. The bear, drift minus one shock, is -0.827630 in log terms, or 630,712 won. Rounded to the nearest 1,000 won, the headline levels are 2,334,000, 1,064,000 and 631,000: plus 61.75 percent, minus 26.26 percent and minus 56.27 percent.

Friday 16 October is the nearer clock, three sessions away, the week the Korea Times says the buyback is set to end. Drift -0.016014, one three-session standard deviation 0.120066. Bull 1,700,308 won, rounded to 1,700,000, or plus 17.81 percent. Base 1,420,075, rounded to 1,420,000, or minus 1.59 percent. Bear 1,259,410, rounded to 1,259,000, or minus 12.75 percent. Those are a check, not the title pair.

Naver’s mean target, dated 12 October, is 3,257,727 won, 125.8 percent above the cash close and 39.6 percent above the bull. It is not an input. On the June EPS of 224,313 won, 1,443,000 is 6.43 times. Estimated EPS of 354,541 won is 4.07 times. Book value of 368,998 won is 3.91 times. The stated dividend is 3,000 won, yield 0.21 percent, dated February 2026, separate from a 375 won distribution that went ex on 28 August. FinanceFeeds reported Samsung’s third-quarter operating-profit guide at 107.4 trillion won. A record guide and a down day can sit together when the seller has lost a buyback bid.

Scenario table

This is not financial advice.

What happens next

Friday 16 October tests the buyback, not a new wafer. If that bid is absent for the three sessions and the stock only realizes the recent drift, the base is 1,420,000 won. One further three-session standard deviation of downside is 1,259,000 won. The chain is a missing corporate buyer plus the net sale already on the tape. It does not require CXMT to publish a yield.

Wednesday 14 October is the first chance for the sidecar rule to fire again: futures down at least 5 percent for a minute, then a five-minute pause on program sells. That would not qualify a 4F2 module. By 31 December the band is 2,334,000, 1,064,000 and 631,000 won. The bull still sits under the 3,257,727 won target. A named customer, a yield and a shipment date were not in the pages saved Tuesday. Until one is, the work was the foreign sale and the 9:47 a.m. sidecar.

Frequently asked questions

Did CXMT’s 4F2 claim reprice SK hynix, or did foreign selling and the sidecar?

Foreign selling and the 9:47 a.m. sidecar did more of the work than a chip that has not shipped. The cash close is 1,443,000 won, down 10.09 percent, a 1.53-standard-deviation day on the last 90 sessions. Cao Kanyu’s 4F2 remarks were made on 9 and 10 October, and they describe a year-end server DDR5 plan. Foreigners were already net sellers last week. The sidecar paused program sell orders for five minutes. It did not halt the stock.

What did SK hynix stock close at on 13 October 2026?

The regular-session close is 1,443,000 won, down 162,000 won, or 10.09 percent, from 1,605,000. The open was 1,538,000 won and the low was 1,425,000 won, on volume of 5,431,079 shares. Naver’s later screen was an after-market last at 20:00 KST, which is why that screen and the 15:30 print differ. Stockanalysis.com marks the cash print at close.

What is a 4F2 DRAM cell, and did CXMT ship one?

No. A 4F2 cell takes about four squares of the minimum line width, against about six for the mainstream 6F2 cell, which is roughly 33 percent less area and room for about 50 percent more cells. CXMT has said it plans server DDR5 RDIMMs on that design by the end of 2026. Yields, customers and shipments were unconfirmed in the pages saved Tuesday. SK hynix has published a road map and no mass-production date.

How were the bull of 2,334,000 won and the bear of 631,000 won calculated?

They are not a broker target. The last 90 daily log-returns, from 1 June through 13 October, with Tuesday at 1,443,000 won, have a mean of -0.00533812 and a sample standard deviation of 0.06932036. Over 57 weekdays to 31 December, the bull is the drift plus 1.5 standard deviations, the base is the drift, and the bear is the drift minus one standard deviation. Unrounded, those are 2,333,776, 1,064,443 and 630,712 won.

Did SK hynix lose $85 billion of market value?

Not on the cash close and the rates saved here. The loss is 730,492,365 shares times 162,000 won, or 118.340 trillion won. At Hana Bank’s 1,341.50 won per dollar that is $88.21 billion. At the 1,345.1 close the Korea Times reported, it is $87.98 billion. The $85 billion figure matches neither rate, so it is not used.

Why do other reports still say the KOSPI fell 7.4 percent?

Because that is the low, not the close. The intraday low of 5,911.11 is 7.41 percent under Monday’s 6,384.24, which is how a 7.4 percent headline and a roughly 5,914 print got written. The close is 6,035.35, down 5.46 percent, and 2.10 percent off the low. ScalpingX carried the close. Other posts carried the scare. Both can be on the same day if the clock is named.