PSK Inc. (319660): Korea’s Dry Strip Toolmaker, Decoded

PSK Inc. makes the machine that strips photoresist off a silicon wafer after it has been patterned — an unglamorous step that happens dozens of times per chip. Its own Korean filing prints a world market share of 40%. The same filing prints something the share number hides: nearly half of what PSK sells is not a machine at all, and three-quarters of last year’s growth came from that half.

Correction, 8 September 2026. Within hours of publishing we found that PSK’s half-year report — a document this article already cites for revenue — prints a newer market-share series than the annual report we quoted, running one year further to 39% in 2025. The original text described the share as flat; on the newer table it slipped. The passages below now carry both series and name the filing each comes from.

🏢 What Is PSK Inc., and What Does It Actually Sell?

PSK Inc. is a 343-person Korean company in Hwaseong that builds front-end semiconductor process tools — chiefly dry strip machines, which use plasma to remove the photoresist mask after a wafer has been patterned — and sells them directly to chipmakers in Korea, China, Taiwan, the US and Japan.

The process itself is old and universal. Every layer of a modern chip is patterned by coating the wafer in a light-sensitive polymer called photoresist, exposing it, etching through the gaps, and then removing whatever resist is left. That removal step is plasma ashing — in Korean filings and in PSK’s own English marketing, “dry strip.” It happens dozens of times in the making of a single logic or memory die, which is why a dry strip tool is a volume purchase rather than a marquee one.

The filing’s own product list is broader than that one word suggests. Under “principal business,” the FY2025 annual report names four families: Dry Strip, Selective Material Removal, New Hard Mask Strip and Bevel Etch, and states the company is “expanding its scope in order to become a global leader in comprehensive process equipment” (Source: DART annual report, rcpNo 20260323000017). Turn to a later section of the same annual report — the segment table headed 사업부문별 주요 제품 — and the list changes: Dry Strip, Dry Cleaning, New Hard Mask Strip, Wafer Edge Clean and Power Device Etch. Five names, three of which did not appear a few sections earlier, and two of which (Selective Material Removal, Bevel Etch) have dropped out. The half-year report’s equivalent table gives a third set, shorter again: Dry Strip, Dry Cleaning, Wafer Edge Clean. So PSK describes its own product range three different ways in two filings, and no two lists match. That is a reminder that these labels are marketing categories rather than accounting ones — because underneath all three, PSK reports as a single segment. There is no product-level profit disclosure anywhere in the filings, and no reconciliation of the three lists either.

One fact worth stating plainly, because it shapes everything a foreign investor can find: PSK Inc. has no English-language Wikipedia entry. We checked PSK_Inc., PSK_Inc and PSK_Holdings on 7 September 2026; all three return 404. A company that its own filing credits with 40% of a world market has no encyclopedia page in the language most of its potential shareholders read. That is not a claim about the company. It is a description of the information gap this article exists to cross.

📊 Where Does PSK’s Revenue Actually Come From?

Just over half of it — 51.8% in H1 2026 — comes from selling machines; the rest comes from a line the filing calls “parts, service fees and other,” and that line has grown from 37.3% of revenue in FY2023 to 48.2% today.

Two things about that “other” line deserve care. First, the filing does not break it down further, so we cannot tell you how much is spare parts, how much is field service, and how much is the “other” in the label. Second, it is overwhelmingly an export line: in H1 2026, $107.8M of the $116.1M was booked as export and only $8.3M as domestic. In FY2025 the same split was $128.1M export against $29.4M domestic. PSK’s installed base outside Korea is where this money comes from.

Geographically, FY2025 was not a normal year. The segment note discloses revenue across five buckets, and two of them changed places:

Note the reversal inside the reversal. China halved across FY2025 — and then grew 29.2% year on year in the first half of 2026. Anyone who read only the annual report would conclude PSK had lost China; anyone who read only the half-year report would never know it had fallen. The two filings tell different stories about the same country, and both are true of their own window.

🗓️ How Did PSK Get Here?

PSK Inc. as a legal entity is only seven years old — it was carved out of PSK Holdings in April 2019 — but it inherited a dry strip business and a development pipeline that the filings trace back to at least 2012.

This matters for anyone looking at a long price chart. The KOSDAQ listing that carries PSK’s pre-2019 history belongs to the other ticker (see the ticker section below). PSK Inc.’s own record starts in May 2019.

🌍 Does PSK Really Have 40% of the World’s Dry Strip Market?

Its FY2025 annual report prints exactly that — a 40% world market share for 2024, sourced to Gartner — alongside a five-year series showing the share peaked at 42% in 2021. But the half-year report filed on 14 August 2026 prints a different five-year window, one year further forward and re-sourced to Gartner’s March 2026 data: 42% (2021), 38%, 40%, 40%, and 39% for 2025. Neither filing states what the denominator is. The two tables overlap on four years and agree on all four; the newer one simply adds the year the older one could not have.

Korean annual reports rarely print market share by year. This one does, and the whole series is worth reproducing rather than the single most flattering point:

The sentence immediately above that table reads: “The Company is consolidating its world market share in the dry strip equipment field, and continues to work to expand it further.” Set that against the table. Share rose once, in 2021, and has moved by two points in the four years since. The prose says expanding; the table says flat. That is management’s characterisation, not a finding — and the table beneath it is the check.

The filing also prints the market PSK is taking share of, from a different Gartner cut:

Two further disclosure gaps belong here, because both are the filing declining to answer rather than us failing to look. PSK does not disclose capacity utilisation: “because equipment is produced to order, capacity can be calculated but its correlation with actual production is low, so disclosure is omitted.” And PSK does not disclose order backlog: “in compliance with customer NDAs and company sales policy, detailed order status is omitted.” A reader who wants forward visibility on this company will not get it from DART.

📈 Is the Business Getting Better or Worse?

Sharply better in 2026, after a FY2025 that looked strong on revenue and flat at the bottom line — half-year revenue rose 54.0% and half-year operating profit rose 125.6%, lifting the operating margin to 30.1% from 19.4% for FY2025 as a whole.

The three-month column matters, because it is easy to mistake for the half. PSK’s half-year income statement prints four columns — Q2 and H1 for 2026, Q2 and H1 for 2025 — and the quarter alone is a large number. For the record: Q2 2026 (the 3개월 column) was revenue of $124.4M and operating profit of $37.3M, against $80.6M and $15.3M in Q2 2025. Both the quarter and the half doubled operating profit. Neither figure is the other one.

FY2025 was more complicated than its revenue line suggests. Revenue rose 14.9%, operating profit rose 5.4% — and net profit fell 0.7%, from $58.8M to $58.4M. The cause was below the operating line: non-operating income dropped from $10.0M to $3.0M as finance costs rose and finance income fell. A lower effective tax rate (15.1% against 18.8%) absorbed most of the rest. The clean way to describe FY2025 is that the operating business grew and the financial result shrank.

Rolling the two together gives a trailing-twelve-month picture that neither filing prints:

🔍 Why Did Three-Quarters of Last Year’s Growth Come From the Line That Isn’t Equipment?

Because PSK shipped fewer machines at lower average prices in FY2025 than in FY2024, and revenue still grew 14.9% — 74.8% of that increase came from parts and services rather than from tools.

Let us state that precisely, because the arithmetic is the point. FY2025 revenue rose by $44.0M. Split by line:

Now the two supporting facts, both printed in the same filing and both pointing the same way.

Unit output fell. PSK’s production table reports 160 tools in FY2023, 191 in FY2024, and 187 in FY2025 — a 2.1% decline in the year revenue grew 14.9%. (The first half of 2026 has already produced 149, which annualises well above any prior year.)

Average selling price fell too. The filing prints an average unit price for “semiconductor process equipment”: ₩1,251M in FY2023, ₩1,453M in FY2024, ₩1,422M in FY2025, and ₩1,382M in H1 2026 — two consecutive declines across three periods from the 2024 peak, a cumulative 4.9%. The filing footnotes that specifications vary by customer order, so this is a mix-weighted average rather than a price list.

Fewer tools, cheaper tools, and revenue up 15%. The gap is the aftermarket line. That is a materially different business model from the one the phrase “semiconductor equipment maker” conjures — it is closer to an installed-base annuity with a capital-equipment front end. We want to be careful about how far to push this: PSK reports as a single segment and gives no profit split by line, so we cannot tell you whether parts and service carry a higher margin than tools. The margin did expand — 19.4% for FY2025 to 30.1% in H1 2026, in a period when the non-equipment share also rose — but that is a coincidence in the data, not a demonstrated cause. Cost, scale, mix and currency all moved at once, and the filings do not decompose them.

Underneath that, FY2025 also saw the customer base change shape. The segment note lists customers accounting for 10%+ of consolidated revenue, anonymised as A, B, C, D and E:

The filing’s own footnote explains the two changes: “Customer D was below the 10% threshold in the prior period and therefore not a disclosure subject; Customer E was a disclosure subject in the prior period but was not disclosed in the current period as its revenue share fell below 10%.”

So a customer worth 21.3% of FY2024 revenue — $63.0M — fell below $34.0M in FY2025 and out of the table. In the same year, China revenue fell by $59.1M. We are not asserting those are the same thing. The filing anonymises customers and does not link them to regions, and we have no independent source that does. What we can say is that both movements are in the same filing, are of similar size, and run in the same direction — and that PSK’s disclosed customer concentration nonetheless rose, from 70.0% to 74.7% and then to 77.3% in the latest half. Losing the largest departing customer did not diversify this company.

Elsewhere on our site we have written about a different flavour of the same problem — Dongjin Semichem selling its China business with Samsung as most of what remains, and HPSP, whose own filing says its market share cannot be calculated. Concentration and unverifiable share claims are close to universal in this corner of the Korean supply chain.

🎯 What Did PSK Promise Its Own Shareholders — and Did It Deliver?

PSK filed a Value-Up plan with four numeric targets for 2026–2030 and then filed a public self-assessment against them: it beat three and failed one, the ESG rating.

Korea’s Value-Up programme asks listed companies to publish voluntary corporate-value plans. Most of what gets filed is aspirational prose. PSK’s is unusually specific, and — rarer still — it comes back a month later and marks its own homework.

Two observations. First, the margin target is remarkable in the other direction: PSK committed to “above 15%” and delivered 19.4% for FY2025 and 30.1% in H1 2026 — double its own floor. A target a company clears by 100% is not a stretch goal; it is a floor set low enough to be safe. Second, and to the company’s credit, it published the failing grade. A Value-Up filing that only reported the three wins would have been entirely within the rules. This one prints the C.

The same filing also records PSK as qualifying as a “high-dividend company” under Article 104-27 of Korea’s Restriction of Special Taxation Act — a status the filing’s own footnote says rests on “the company’s own judgement” (기업의 자체적인 판단에 의함), not on a regulator’s determination — with FY2025 dividends of $14.6M against FY2024’s $8.6M — a 70.0% increase, the figure the disclosure itself computes.

💰 What Do You Actually Pay for PSK Today?

At the 4 September 2026 close of ₩126,500 (~$94), PSK is a $2.72B company trading at 46.7× FY2025 earnings, 29.3× trailing-twelve-month earnings, and 6.0× book — after a 242.8% year-to-date move that still leaves it 40.2% below its 52-week high.

Against Korean peers, PSK sits in the middle of the sector on price and near the bottom on margin:

🏷️ Which PSK Ticker Are You Actually Buying?

There are two listed companies called PSK on KOSDAQ, and they make different things: 319660 is the front-end tool business, while 031980 (PSK Holdings) makes back-end packaging equipment and separately owns 32.76% of 319660 directly.

This is the single most likely way for a foreign investor to buy the wrong security here. The confusion has a specific origin: the original listed company was called PSK Inc. On 1 April 2019 it renamed itself PSK Holdings and spun out a new PSK Inc. So a long price chart labelled “PSK” — and any pre-2019 financial history — belongs to 031980, not to the ticker most people mean today.

There is a valuation consequence to that structure worth doing the arithmetic on. PSK Holdings’ own 9,489,994 shares of PSK Inc. — the reporting entity’s line in the large-holding filing, before the group executives who are counted alongside it — were worth $891.9M at the 4 September close. PSK Holdings’ own market capitalisation was $2.31B. So the stake in the listed subsidiary accounts for 38.7% of the parent’s market value; the remaining $1.41B is the market’s price for a packaging-tool business that did $154.4M of FY2025 revenue at a 35.3% operating margin. We have not opened PSK Holdings’ full accounts for this article and are not offering a view on whether that is cheap or dear — but a reader comparing the two tickers should know that buying 031980 is roughly 61% a bet on back-end packaging tools and 39% a look-through claim on 319660.

We found no American Depositary Receipt for either ticker. Neither appears in our list of Korean stocks available as US-listed ADRs. Foreign buyers use the Korean line — see how to buy Korean stocks as a foreign investor, and how won prices convert to dollars. That is a statement about where we looked, not a guarantee that no instrument exists anywhere.

🌏 Is Foreign Money Buying or Selling PSK?

Both — and which answer you get depends entirely on the window you pick: over the twenty sessions to 4 September 2026 foreigners were net buyers of PSK Inc. (319660), over the fifty-five sessions we hold they were net sellers, and Korean institutions took the opposite side in each. The table below gives both windows rather than the flattering one.

The sign flips, so the headline flips. A story built only on the twenty-session column reads “foreigners are accumulating PSK.” A story built only on the fifty-five-session column reads “foreigners are exiting PSK.” Both would be arithmetically correct and both would be misleading on their own. What the two columns together actually say is narrower and more useful: foreign investors sold into the earlier part of the summer and have been buying back over the last month, while domestic institutions did the reverse in each window and remain net buyers across the full period. Nobody in this table is a stable holder.

The price does not obviously reward either side. Across the 55-session window in which foreigners were net sellers, PSK fell 26.5% — the institutions were buying into that decline. Across the 20 sessions in which foreigners were net buyers, the stock rose 6.8%, and the institutions were selling into it. We are describing sequence, not causation: with two large counterparties on opposite sides of every one of these windows, no flow column here explains the price on its own.

The institutional side shows up in the filing record too. Three 5%-plus positions were reported in 2026 filings — one of them the controlling shareholder — and the FY2025 annual report footnotes two more on older basis dates:

🏛️ Who Controls PSK, and What Do Minority Holders Get?

PSK Holdings, itself listed on KOSDAQ, controls 32.84% including related parties — and minority holders get a rising cash dividend and nothing else: PSK holds zero treasury stock and has cancelled no shares since 2022.

Be careful with the control number, because the filings give two. The FY2025 annual report’s shareholder table shows PSK Holdings alone at 9,489,994 shares, or 32.76%, as of 31 December 2025. The July 2026 large-holding report — the one that must include related parties — shows 9,513,482 shares, or 32.84%. The 23,488-share gap is nine individuals the filing lists as 특별관계자, and it names their relationship to the reporting entity in a single repeated phrase: 계열회사 임원 — officers of group companies. There are no family members on the list. Quote the wrong number and you either understate the control block or credit the parent with shares its executives hold personally; this is precisely the kind of two-number sentence Korean filings are full of, and the July filing prints both, one table apart.

The float is unusually wide for a Korean company at this level of control. The annual report records 28,439 small shareholders holding 17,687,209 shares — 61.07% of the register as of 31 December 2025. There is no cross-shareholding web here, no circular ownership, and no preferred share class: one common line, 28,966,714 shares, and zero treasury stock.

That last fact deserves emphasis in a Value-Up context. Korea’s reform push has centred on buybacks and, above all, on cancellation — retiring shares permanently to shrink the count. PSK did that once, in July 2022, retiring 281,663 shares; two months later it issued 14,483,357 new shares in a bonus issue that capitalised the share-premium account. Since then: no buyback, no cancellation, no treasury holdings at all. PSK’s entire shareholder-return policy is the dividend.

On board structure, the filings record a chairman (Park Kyung-soo, born December 1952) who is simultaneously CEO of the controlling shareholder, PSK Holdings — and who holds no shares in PSK Inc. himself. The two co-CEOs, an inside director and the chairman hold cross-appointments across the group’s overseas subsidiaries. Outside directors were appointed in 2024 and 2025. The KCGS overall grade the company reports against itself is C.

📚 Lingo Check

🎯 Why It Matters for K-Export Stars

Everything decisive in this article was in Korean and nowhere else. The five-year market-share series, the 51.8/48.2 revenue split, the falling unit count, the customer that dropped off the disclosure table, the Value-Up scorecard with its one failing grade — all of it sits in two DART filings that have no English version, filed by a company with no English Wikipedia page. The English-language record of PSK Inc. is a market-share number and a ticker.

That gap is the whole reason this site exists. Korea’s semiconductor supply chain is dense with companies like this one: small enough that no Western broker covers them, essential enough that the chipmakers everyone does cover cannot ship without them. Reading their filings is not exotic analysis. It is just reading — in the language they were written in.

This company is one of ten in our K-Semiconductor Filing Map — a supply-chain map where every cell is marked by what the filing itself supports, and each one links to the receipt number it came from.

Disclaimer: This article is for informational and educational purposes only. It is not investment advice, an offer, or a solicitation to buy or sell any security. All figures are drawn from public regulatory filings and market data as of the dates stated and will go out of date; prices, multiples and flow figures in particular change daily. K-Export Stars holds no position in PSK Inc. or PSK Holdings. Do your own research and consult a licensed adviser before making any investment decision. See our corrections policy.