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UMC — structural market context

United Microelectronic Corp.

Structural market context from public regulatory and market data, shown with its as-of dates. Descriptive only: nothing on this page is a recommendation, a prediction, or advice to buy or sell any security.

What changed

As of the close on Oct 21. Each line shows the earlier value, the later value and their dates.

Price

Close $19.82 (Oct 21) vs $19.67 (Oct 20): +0.76%.

Volume

0.78× its 20-session average (10.6M) on Oct 21.

Includes pre- and post-market trading.

Short interest

Short interest 27.8M shares (settlement Sep 30) vs 38.4M (Sep 15).

No new publication in this window. Latest: settlement Sep 30, published Oct 10.

Fails-to-deliver

Latest file (settlements Sep 15–Sep 30, published Oct 16): 6 days with fails, largest 285K shares on Sep 21.

Previous file (settlements Sep 1–Sep 14, published Sep 30): 9 days with fails, largest 585K shares on Sep 3.

No new publication in this window.

Insider filings (Form 4)

None recorded in this window.

UMC events and their magnitude

Latest SEC filing in the event study

Form 4 · sale · filed 2026-09-22 · View on sec.gov ↗

…

Open the Event Study →

UMC short interest & days to cover

SHARES SHORT
27.8M
% OF FLOAT
1.3%
DAYS TO COVER
2.4
CHANGE VS PRIOR
-27.6%

FINRA consolidated short interest, reported twice a month and published ~2 weeks after each settlement date. % of float uses reported free float. · as of 2026-09-30 (22d ago)

UMC fails-to-deliver (FTD)

Settlement dateFailed sharesPrice
2026-09-30 · 22d3K$24.72
2026-09-29 · 23d608$23.85
2026-09-21 · 31d285K$24.61

SEC fails-to-deliver files, published twice a month with ~6 weeks of delay.

UMC insider buying and selling (Form 4)

Last 12 months, Form 4 codes P and S: 0 purchases · 0 sales · 2 filings not counted

InsiderTypeSharesValueFiled
LIN JEN-TSUNG · officer: Vice PresidentSale (S)10K—*2026-09-22
Liu Chitung · officer: CFO & SVPSale (S)400K—*2026-09-17
Liu Chitung · officer: CFO & SVPSale (S)1.2M—*2026-09-17

*Value not shown: the filed price could not be checked against the U.S. listing.

SEC Form 4 filings: purchases and sales reported on Form 4 (transaction codes P and S) only; grants and option exercises excluded. Attributed public records.

Frequently asked questions

What is UMC's short interest?
As of the FINRA settlement date 2026-09-30, UMC had 27.8M shares sold short — 1.3% of its float, with 2.4 days to cover at average volume. FINRA publishes this data roughly two weeks after each twice-monthly settlement, so it is inherently delayed. A short-interest figure describes an aggregate position; it does not predict what the stock will do.
Are insiders buying UMC?
In the last 12 months of SEC Form 4 filings, UMC recorded 0 insider purchases and 0 sales reported on Form 4 (transaction codes P and S; grants and option exercises excluded). 2 filings not counted: the filed price could not be checked against the U.S. listing. These are attributed public records — information, not instruction.
Is this page telling me to buy or sell UMC?
No. Everything on this page is descriptive, structural market context from public data, shown with its as-of dates. TradeAI News does not issue directional recommendations, price predictions, or buy/sell advice — for any ticker.
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UMC: the full history

Latest rows shown. Full history, market-wide screens, cluster detection and the context journal live in the dashboard.

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Not financial advice. Trading involves risk. Descriptive structural context, never a recommendation.