---
title: "United Microelectronics CFO's stake fell 28.4% in September; insiders sold $526 million and bought nothing"
description: "The foundry's Form 6-K, filed October 23, 2026, shows chief financial officer Chitung Liu's stake fell 28.4% in September, inside a twelve-month stretch where insiders sold $526.4 million and bought nothing. On October 28 the market finds out whether the AI-power story can carry a multiple already 52% above its own five-year median."
publisher: "The Inference"
section: "Chips"
published: 2026-10-23T14:13:25.644Z
modified: 2026-10-23T14:13:25.644Z
canonical: https://theinference.org/article/united-microelectronics-cfo-s-stake-fell-28-4-in-september-insiders-sold-526-million-and-bought-nothing
language: en
keywords: "Insider Trades, Semiconductors, Foundries, Earnings, AI Chips"
---

# United Microelectronics CFO's stake fell 28.4% in September; insiders sold $526 million and bought nothing

> The foundry's Form 6-K, filed October 23, 2026, shows chief financial officer Chitung Liu's stake fell 28.4% in September, inside a twelve-month stretch where insiders sold $526.4 million and bought nothing. On October 28 the market finds out whether the AI-power story can carry a multiple already 52% above its own five-year median.

The filing landed this morning with almost no noise around it: [a Form 6-K](https://www.sec.gov/Archives/edgar/data/1033767/000119312526429369/0001193125-26-429369-index.htm) from [United Microelectronics](https://theinference.org/markets/companies/united-microelectronics), the Taiwanese chip foundry whose New York shares have more than doubled in a year [3]. Inside it, in a monthly insider table, is the September book of the company's own finance chief. [Chitung Liu](https://theinference.org/markets/people/chitung-liu), who signs the 6-K as CFO, held 2,112,917 UMC common shares on August 31 [1]. On September 30 the table shows 1,512,917 [1]. That is 600,000 shares gone in one month, 28.4% of the stake [1].

A vice president, JT Lin, trimmed 10,000 shares in the same window [1]. The filing carries no prices and no proceeds, only the before-and-after counts [1].

## The sale sits five days in front of the number that tests it

UMC reports third-quarter earnings on October 28, before the open [4]. [MarketBeat's consensus](https://www.marketbeat.com/instant-alerts/upcoming-united-microelectronics-umc-set-to-announce-quarterly-earnings-on-wednesday-2026-10-21/) puts the print at $0.23 of earnings per share on $2.33 billion of revenue, against $0.53 and $2.16 billion last quarter [4]. The headline drop looks like a collapse. It is mostly arithmetic: in the June quarter, CFO Liu told investors that investment and dividend income of roughly TWD 30 billion arrived as non-operating income, which is why net income hit TWD 42.26 billion, a 61.5% net margin on a business whose operating margin was 21.8% [9].

Strip that windfall and the consensus quarter is a normalization, not a verdict. What remains unexplained is everything else: why the stock still trades at $18.53, 100.5% above [GuruFocus's $9.24 value estimate](https://www.gurufocus.com/news/9138244/a-look-at-united-microelectronics-corp-umc-after-65-decline-gf-value-924-vs-price-1853), with a trailing P/E of 17.7x against a five-year median of 11.7x [2].

*Chart: **UMC revenue climbed back to 2.16 billion dollars by mid-2026** Column chart of UMC quarterly revenue in USD billions from Q1 2024 through Q2 2026, rising from about 1.7 to about 2.16 billion dollars.*

*Consolidated quarterly revenue, USD billions, from UMC's SEC filings as compiled on October 23, 2026. [10]*

*Chart: **Q2 2026 net income spiked to 1.33 billion on investment gains, not wafers** Column chart of UMC quarterly net income in USD billions, mostly 0.2 to 0.5 billion, spiking to 1.33 billion in Q2 2026.*

*Quarterly net income, USD billions, from UMC's SEC filings as compiled on October 23, 2026; the June 2026 quarter includes roughly TWD 30 billion of non-operating investment and dividend income per the CFO's earnings-call remarks. [10]*

## The AI story is real, early, and already priced

The rally has a narrative. On October 22, UMC and AP Memory [announced a partnership on deep-trench capacitor silicon](https://www.prnewswire.com/news-releases/umc-and-ap-memory-collaborate-to-enable-advanced-power-delivery-solutions-for-ai-and-hpc-systems-302916408.html), the components that carry stable voltage into AI chips inside the package rather than across the board; AP Memory's Gen2D designs taped out in the third quarter [5].

On the July earnings call, CEO Jason Wang put 2026 AI-related revenue near $300 million and said it would exceed $1 billion within three years [9]. The company raised its 2026 capital budget to $2 billion from $1.5 billion, and financed the build with [$1.8 billion of zero-coupon convertible bonds priced October 5](https://finance.yahoo.com/markets/stocks/articles/umc-stock-slides-1-8b-152314686.html), money investors effectively pay UMC to hold [8][9]. The stock fell about 10% that day anyway [7].

## What the insiders did while the story compounded

The ADR returned 136.88% over twelve months against 58.96% for Taiwan's benchmark, and [closed October 22 at $18.53, down 6.51% on 17.6 million shares against a 12.3 million average](https://ca.finance.yahoo.com/quote/UMC/) [3].

Against that tape, GuruFocus counts $526.4 million of insider selling over the past year with no buying reported, and the September table adds the CFO's 28% reduction and an empty pledge ledger [1][2]. Nothing here proves motive; the filing shows counts, not reasons [1]. But positions speak louder than press releases, and the people closest to the wafers have been selling the rally, not joining it.

## The bulls have their quarter, and their target

The counter-case deserves its due: third-quarter guidance called for shipments up high single digits, utilization above 90%, and gross margin in the mid-30s, the best operating setup in years [9]. Wall Street's consensus target is $19.12, with a high of $33.76 [3]. If the AI power and silicon-photonics pipeline converts on schedule, today's premium looks like a down payment, not a mistake [5][9].

## Watch Wednesday, then the October insider table

The October 28 print settles the first question: whether operations, not investment income, can carry a 17.7x multiple [4][9]. The November 6-K settles the second: whether September's selling was a finish or a habit [1]. Until both read out, the buyer of the AI-power story is the one holding shares the sellers would not.

## Takeaway

UMC's own finance chief cut her stake 28.4% in September while insiders sold $526 million over a year and bought nothing; on October 28 the quarter settles whether a 17.7x multiple, 52% above its five-year median, rests on wafers or on one quarter of investment income.

## Sources

1. [SEC EDGAR, United Microelectronics Corp Form 6-K, filed 23 October 2026 (Exhibit 99.1 and 99.2)](https://www.sec.gov/Archives/edgar/data/1033767/000119312526429369/0001193125-26-429369-index.htm)
2. [GuruFocus, A Look at United Microelectronics Corp (UMC) After 6.5% Decline, 22 October 2026](https://www.gurufocus.com/news/9138244/a-look-at-united-microelectronics-corp-umc-after-65-decline-gf-value-924-vs-price-1853)
3. [Yahoo Finance Canada, United Microelectronics Corporation (UMC) quote page, 23 October 2026](https://ca.finance.yahoo.com/quote/UMC/)
4. [MarketBeat, United Microelectronics (UMC) Set to Announce Quarterly Earnings on Wednesday, 21 October 2026](https://www.marketbeat.com/instant-alerts/upcoming-united-microelectronics-umc-set-to-announce-quarterly-earnings-on-wednesday-2026-10-21/)
5. [PR Newswire, UMC and AP Memory Collaborate to Enable Advanced Power Delivery Solutions for AI and HPC Systems, 22 October 2026](https://www.prnewswire.com/news-releases/umc-and-ap-memory-collaborate-to-enable-advanced-power-delivery-solutions-for-ai-and-hpc-systems-302916408.html)
7. [Yahoo Finance / Michael Douglass, AI Stock UMC Sinks 10% on $1.8 Billion Worth of Extraordinarily Good News, 5 October 2026](https://finance.yahoo.com/markets/stocks/articles/ai-stock-umc-sinks-10-173724806.html)
8. [StockTwits via Yahoo Finance, UMC Stock Slides After $1.8B Convertible Bond Pricing, 5 October 2026](https://finance.yahoo.com/markets/stocks/articles/umc-stock-slides-1-8b-152314686.html)
9. [Yahoo Finance / Quartr, United Microelectronics Q2 FY2026 earnings call transcript, 29 July 2026](https://finance.yahoo.com/quote/UMCB.MU/earnings/UMCB.MU-Q2-2026-earnings_call-549690.html)
10. [United Microelectronics quarterly figures from SEC filings, compiled 23 October 2026](https://www.sec.gov/cgi-bin/browse-edgar?action=getcompany&CIK=0001033767)


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United Microelectronics CFO's stake fell 28.4% in September; insiders sold $526 million and bought nothing — The Inference. Canonical: https://theinference.org/article/united-microelectronics-cfo-s-stake-fell-28-4-in-september-insiders-sold-526-million-and-bought-nothing