Micron sinks 17.5% in its worst session since 2020

Micron Technology shares lost 17.46% on Nov 5. They closed at US$656.39 on the Nasdaq, down from US$795.23 the session before. No single trading day had cost the memory maker more since March 2020.

The whole chip group fell that day, but Micron fell harder. The PHLX Semiconductor Index, a gauge of US-listed chip stocks, declined 12.25% over the same session. Micron’s loss was about five percentage points deeper than the index’s.

The deepest one-day loss in over five years

The last time Micron dropped as much in one session was March 16, 2020, when the stock gave up 19.8%. That day came 1,669 trading sessions before this one. No session in between matched the Nov 5 decline.

The drop added to a slide that was already under way. From Oct 16 through the Nov 5 close, Micron shares lost 25.31%. Pacific Tape covered Micron’s earlier moves on Nov 5 in a separate story.

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Barron’s points to lost market share

Barron’s linked the renewed slump to Micron’s shrinking share of its market. The same Barron’s piece also argued that the decline offers an opportunity. That is the outlet’s opinion, not a finding, and the market-share explanation is Barron’s own reading of the move.

A slump weeks after a six-quarter profit high

The sell-down came about a month after Micron filed its 10-K, the annual report US companies submit to securities regulators, on Oct 9. The report covered a quarter of rapid growth.

In the fiscal fourth quarter, which ended September 3, 2026, Micron’s revenue reached US$54.229 billion. That was 30.81% more than in the quarter before and 379.27% more than a year earlier.

Fiscal Q4 2026	Amount	vs prior quarter	vs year earlier
Revenue	US$54.229 billion	+30.81%	+379.27%
Operating profit	US$43.751 billion	+31.31%	+1,097.35%
Net income	US$37.701 billion

Operating profit, the earnings from the core business before interest and taxes, rose to US$43.751 billion. It was the highest in at least six quarters. It rose 31.31% from the prior quarter and 1,097.35% from the same quarter a year earlier. Net income came to US$37.701 billion.

Those figures describe a quarter that closed in early September. They do not explain the Nov 5 decline, and no outlet tied the drop to the results.

Seoul and Taipei open in the red

The losses carried into Asian trading on Nov 6. CNBC reported that the Nasdaq rout hit chip shares across Asia, naming SK hynix and Samsung Electronics among the decliners.

The Korea Herald gave a different reason for the drop in Korea’s two big memory makers. It connected their slide to widening worries about AI data centers. Those are the large computing sites whose spending has driven demand for memory chips.

In Taiwan, Focus Taiwan reported that TSMC shares fell to their daily price limit in early Taipei trading on Nov 6. The limit is the furthest a stock may fall in one session under exchange rules.

For investors in Samsung and SK hynix, the US session is the first signal each morning. Micron and the two Korean companies are the main makers of DRAM, the working memory used in servers and phones. A drop in Micron is therefore read closely in Seoul. On Nov 6, the Korean pair opened lower, and the outlets that reported it gave different explanations. Barron’s pointed to Micron’s market share. The Korea Herald pointed to concern over data center spending.

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Information only, not investment advice.