GCT Semiconductor Holding, Inc. (GCTS)

GCT is a fabless chip company, meaning it designs chips and pays others to make them. Its chips connect devices to cellular networks: baseband modems that encode and decode the data, radio transceivers (RF) that send and receive the signal, and single chips that combine the two, sometimes with a processor and memory. Its 4G LTE range runs from high-speed 4.75G chips down to low-power chips for the Internet of Things, and its first 5G chipset began commercial shipments in the fourth quarter of 2025. The chips go into fixed wireless routers (CPE, the boxes that bring home internet over a mobile network in place of a DSL, cable or fiber line), mobile hotspots (MiFi), communication modules and industrial equipment; the filing says they suit virtually every wireless broadband data device except smartphones. Its modem chips come with software, source code included, and customers get design support, including reference designs that show how to connect the chips to the rest of a device. 26272829303132333435

How it operates

GCT is a fabless chip company, meaning it designs chips and pays others to make them. Its chips connect devices to cellular networks: baseband modems that encode and decode the data, radio transceivers (RF) that send and receive the signal, and single chips that combine the two, sometimes with a processor and memory. Its 4G LTE range runs from high-speed 4.75G chips down to low-power chips for the Internet of Things, and its first 5G chipset began commercial shipments in the fourth quarter of 2025. The chips go into fixed wireless routers (CPE, the boxes that bring home internet over a mobile network in place of a DSL, cable or fiber line), mobile hotspots (MiFi), communication modules and industrial equipment; the filing says they suit virtually every wireless broadband data device except smartphones. Its modem chips come with software, source code included, and customers get design support, including reference designs that show how to connect the chips to the rest of a device. 26272829303132333435

It rarely sells to the carriers themselves. Its buyers are the companies that build devices for them: equipment makers (OEMs), design manufacturers (ODMs), contract manufacturers, system integrators and distributors, all on purchase orders. The carriers still weigh heavily, because a device must pass each operator's own testing before it can be sold for that network; GCT's chipsets have been certified with Verizon, AT&T, T-Mobile, US Cellular, KDDI, SoftBank and the three major South Korean operators. Revenue rests on very few buyers: four customers took 74% of 2025 revenue and four took 73% of 2024's, but not the same four. The largest in 2025, Customer M in the filing's lettering, took 23% after 25% a year earlier and is the only one above a tenth of revenue in both years. Winning a sale usually takes 12 months or more, since the chip is chosen when the device is designed; once chosen, it is costly for the customer to switch for that product. 36373839404142

It earns money two ways. Product revenue, from chips, is generally booked when they ship; service revenue, from development services, platform solutions, technical advice and maintenance, is booked as the work is done. In 2025 service was the larger part: 1.7 million dollars, 60.5% of revenue. The main development deal the filing describes is a joint development agreement signed in 2019 with a leading worldwide wireless operator that it does not name, a relationship of more than 13 years: GCT designs 5G chipsets for fixed wireless, mobile broadband and modules, and the operator pays a one-time fee as each development milestone is reached. The operator gets most-favored terms on supply and rebate fees on worldwide sales of the chips, can end the deal at any time on written notice, and GCT keeps the intellectual property in the chips. To device makers, GCT presents itself as the less costly alternative to the dominant supplier, with lower upfront licensing costs and no further licensing fee once a product is on sale. 4344454647484950515253

By where its customers are, the United States brought in 1.6 million dollars in 2025, 55.9% of revenue, against 4.2 million the year before; Taiwan 629 thousand, 21.9%; China 411 thousand, 14.3%; Germany 142 thousand, 5.0%; and South Korea 82 thousand, 2.9%, down from 3.5 million. The work spans the Pacific: sales, marketing and accounting are run from headquarters in San Jose, California, while product design, development and customer support sit in wholly owned subsidiaries in South Korea, one of them the research and development center, with sales offices for local support in Taiwan, China and Japan. 4654

It owns no factories. Samsung Foundry and UMC are its main wafer makers: Samsung makes its 4G modems on a 28-nanometer process and its 5G modems on 8 nanometers, UMC makes 4G modems and 4G and 5G radio chips on 40-nanometer processes, and TSMC makes some 4G radio chips. Hana Micron, Stats ChipPAC and ASE do most of the assembly and testing, on purchase orders, and no long-term agreement guarantees it foundry capacity. Since February 2024, Alpha Holdings has worked on its 5G chips under a three-year agreement to develop and deliver products made in Samsung's foundry, at a total development cost since raised to about 7.7 million dollars; that agreement replaced a 2020 research and development deal with Samsung itself, which was terminated. 5556575859606162636465

The specifics

GCT began operations in 1998 and, in its own words, has recorded losses every year since; its accumulated deficit reached 605.4 million dollars at the end of 2025. It made its name in 4G: it says it was one of the first suppliers of 4G LTE chips, and in 2015 the first to commercialize 4.5G chips with four-antenna (4x4 MIMO) reception. It became a public company on March 26, 2024 by combining with Concord Acquisition Corp III, which had listed in November 2021; GCT became its wholly owned subsidiary and Concord took the name GCT Semiconductor Holding. The deal was accounted for as a reverse recapitalization, with GCT treated as the acquirer, and brought in 17.2 million dollars net together with a private placement. Its shares are listed on the New York Stock Exchange as GCTS. In the first quarter of 2024, Samsung released GCT from paying for work under their 2020 agreement to develop 5G chips, the filing citing unmet development milestones and a change in Samsung's business strategy, which gave 2024 a one-time gain of 14.6 million dollars. 6667686970197172737464

The annual report carries a warning: the auditor's report includes a paragraph expressing substantial doubt that the company can continue as a going concern. At the end of 2025 it held 0.6 million dollars in cash and owed lenders 62.6 million in principal, 56.6 million of it due within twelve months, and its liabilities of 98.9 million dollars far exceeded its assets of 15.6 million. It relies substantially on South Korean lenders and partners, in its own words, and above all on related parties: Anapass, its largest shareholder, had lent 29.6 million dollars and put up deposits as collateral for a bank loan, and the chairman lent 2.9 million and 2.1 million dollars late in 2024; his loans that ran past their due dates carried a penalty of 3% of principal a month, 2.9 million dollars in 2025. Loans that fell due in 2025, with KEB Hana Bank, IBK Industrial Bank and others, were renegotiated. It also raises money from investors: an at-the-market program of up to 75.0 million dollars, a direct offering that netted 9.9 million in May 2025, and convertible-note lines of up to 20.0 million dollars each from Indigo Capital in December 2025 and Obsidian Global in March 2026. 757677787911808182838485868788

Its technical calling card is reception with many antennas. It says it was the first to offer an eight-antenna LTE chip, which lets a fixed wireless router keep a clean signal when a cell tower beams to many nearby devices at once and the beams interfere, and it is carrying the same technique into 5G. Its modems are built from dedicated hardware blocks rather than the programmable signal processors (DSPs) of traditional designs, which it says lets it scale one design into several products on lower-cost wafer processes without cutting features. It protects this with about 86 patent rights at the end of 2025: 58 on modem design, 20 on radio transceivers and 8 on frequency synthesis; by country, 34 in the United States, 34 in Korea, 7 in Taiwan, 5 in Japan, 4 in China and 2 elsewhere. 899091929394959697

It names its rivals. In mid-range and low-end 4G wireless broadband they are Qualcomm, MediaTek, HiSilicon and Sequans; in high-speed 4.75G and 5G broadband, chiefly Qualcomm and MediaTek, while Samsung LSI concentrates on modems for smartphones. It notes that HiSilicon has struggled under political sanctions, and that rules in the United States, the European Union, South Korea and Japan limiting sales by Chinese companies have benefited it in the past, with no guarantee they continue. Every product also passes through the US Commerce Department, which assigns it the export classification it needs to ship, and GCT seeks to have products reclassified as non-strategic where it can, to ease the limits on exporting them. 9899100101102103

What drives growth, line by line

Revenue fell 68.6% in 2025 to 2.9 million dollars, after 16.0 million in 2023 and 9.1 million in 2024. Gross profit turned into a loss of 1.8 million dollars, against a gross margin of 56% in 2024, because, the filing says, product revenue was too small to absorb production overheads. The operating loss widened to 36.5 million dollars from 13.1 million; 2024's had been softened by the 14.6 million gain from Samsung's release, while 2025 carried a 2.8 million charge for receivables that may not be collected. The net loss was 43.4 million dollars, and operations used 30.7 million in cash. 10410574106

Service. The larger line in 2025: 1.7 million dollars, 60.5% of revenue, down 60.2%. The filing puts the fall down to the substantial completion of a significant service project in 2024, which meant a smaller portfolio of service work in 2025; service costs fell in step with the work. 46107108

Product. 1.1 million dollars, 39.5% of revenue, down 76.3%. Sales of 5G platforms had brought in 3.9 million dollars in 2024 and none in 2025, and the first 5G chipsets shipped only in the fourth quarter. The line cost more to make than it brought in: product costs rose to 4.0 million dollars, driven by 1.0 million of added production overhead, 0.7 million more in charges for slow-moving inventory and higher depreciation. 4610930110

What comes next, in the company's own words: with its first 5G chipset shipping since the fourth quarter of 2025 and other 5G chips expected to become available during 2026, it expects its 5G chips to sell for about four times as much, on average, as its 4G chips, and expects 5G product sales to contribute more significantly to revenue later in 2026, which it says should improve operating efficiency. It plans more 5G chips for vehicle communication (C-V2X), satellite links (non-terrestrial networks) and a 5G standard for Internet of Things devices (RedCap), and it anticipates continued demand for its 4G chips, which it says are expected to coexist with 5G as the lower-cost option for some time. 30111112113114115

The read's section on the people who run it is on the People tab.

What the desk infers Inferred

1. Inferred

   The leading worldwide wireless operator that the filing leaves unnamed, GCT's partner in the 2019 joint development agreement for 5G chips, is most likely Verizon.

   Because

   • GCT signed the joint development agreement with the operator in 2019 and describes a close relationship with it of more than 13 years. 4748
   • Among its material contracts it lists a general services agreement with Verizon Sourcing LLC dated December 20, 2019, the year of the joint development agreement, and a statement of work with the same party dated December 22, 2020. 116117
   • Its risk factors describe a development and collaboration agreement for 5G with a Tier 1 wireless communications operator. 118
   • Verizon heads the list of operators that have certified its chipsets. 38
   • Customers in the United States brought in 55.9% of 2025 revenue, more than any other place. 46
   Confidence 80 of 100Wrong if A filing that names a carrier other than Verizon as the party to the 2019 joint development agreement, or shows that the Verizon agreements cover work unrelated to 5G chip development.
2. Inferred

   The company's two related-party lenders are best read as one circle around its chairman, and that circle supplies most of the money it borrows: Dr. Lee sits on the board of Anapass, its largest lender and largest shareholder, and lends to the company himself.

   Because

   • Dr. Lee has chaired GCT's board since 2000 and has sat on the board of Anapass since 2002. 9
   • Anapass holds 12.4% of the shares, the only stake above five percent in the ownership table, and the board weighed Dr. Lee's relationship with a major stockholder, and his loans, when judging him independent. 1113
   • At the end of 2025 the related-party table shows 29,619 thousand dollars borrowed from Anapass and 8,711 thousand from Dr. Lee, out of 62.6 million owed to lenders in principal; the two banks named, KEB Hana and IBK Industrial, had lent 6.3 and 6.4 million. 1197780
   • In 2025 alone Anapass made new loans of 3.1, 2.1, 1.4 and 10.7 million dollars, and Dr. Lee one of 4.4 million. 120121
   • The company says it remains dependent on related-party debt financing, including loans from Anapass and Dr. Lee. 122
   Confidence 70 of 100Wrong if A filing showing that Dr. Lee holds no seat or stake at Anapass, or that most of the company's borrowing comes from lenders with no tie to him or to Anapass.
3. Inferred

   GCT turns revenue into cash slowly, and part of what it is owed is already in doubt: its development contracts let it book revenue long before it can bill, and much of what it has billed sits with customers that show no 2025 revenue in the filing's table.

   Because

   • Contract assets, revenue earned but generally not yet billable, stood at 5,432 thousand dollars at the end of 2025, more than the whole year's revenue. 123124104
   • All service revenue is booked over time, while the main development deal pays a one-time fee only as each milestone is achieved. 4449
   • Customers F and K, with 16% and 22% of 2024 revenue and no share of 2025's, held 23% and 28% of gross receivables at the end of 2025. 40125
   • The provision for credit losses rose to 4.0 million dollars from 1.2 million, after a 2.8 million charge in 2025. 126106
   Confidence 65 of 100Wrong if A later filing showing the contract assets billed and collected within a year and the balances of Customers F and K paid in full, with the credit-loss provision released.
4. Inferred

   The strategic investor that lent 5.0 million dollars on a convertible note in February 2024, a note tied by covenant to GCT's 5G work and since extended to February 2028, is Gogo Business Aviation.

   Because

   • The notes to the accounts say a convertible note of 5.0 million dollars was issued to a strategic investor in February 2024, with a covenant on the company's performance of its 5G obligations. 127128
   • The exhibit list names a convertible note dated February 26, 2024 between GCT Semiconductor, Inc. and Gogo Business Aviation LLC. 129
   • The other convertible notes issued that February and March went to a group of investors, were automatically convertible upon the listing, and none remained outstanding at the end of 2025. 130131
   • The strategic investor's 2024 notes were extended in February 2026 to February 2028, and the exhibit list shows an amendment to a convertible note with its holder dated February 24, 2026. 132133
   Confidence 80 of 100Wrong if A filing naming a holder other than Gogo Business Aviation for the 5.0 million dollar convertible note issued to a strategic investor in February 2024.