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TSEM Semiconductors · Analog foundry · AI infrastructure · Silicon photonics · Thesis updated July 20, 2026

AI optics made Tower the one to watch

01 Running thesis

The AI optics bet got bigger

Tower makes specialty analog chips for other companies. Its hottest area is RF Infrastructure, especially silicon photonics, often called SiPho. SiPho helps move data with light inside optical modules used in AI data centers. That business reached 32% of corporate revenue in Q4 2025, and SiPho alone produced $95 million in the quarter.

The bull case is simple but not small. Tower is adding a lot more SiPho capacity because demand is strong. Management lifted its expansion target from more than 3 times to more than 5 times the Q4 2025 baseline by late 2026. More than 70% of that new capacity is reserved or being reserved through 2028, backed by customer prepayments.

Management also put out a 2028 model of $2.84 billion in revenue and $750 million in net profit. If Tower fills the new lines at good pricing, the company could look much larger than it does today. That is why performance looks strong, even while the stock price may already assume a lot of this goes right.

The bear case is that the growth area is now the main story. Active Copper Cable component forecasts have been cut as data center designs change. If AI optics demand pauses after Tower spends heavily, utilization could fall. Intel has also said it does not intend to perform under the September 2023 Fab 11X agreement, and the companies are in mediation.

Feb 2026Q4 2025 made the SiPho thesis much bigger. RF Infrastructure reached 32% of revenue, SiPho hit a $380 million annual run rate, and management raised the capacity goal to more than 5 times the Q4 baseline.
Nov 2025Tower raised its SiPho expansion target to more than 3 times Q4 2025 levels and said 300mm silicon photonics revenue should start in Q4 2025. The Newport Beach fab lease was also extended, reducing a prior site risk.
Aug 2025RF Infrastructure rose to 25% of revenue, and Tower prototyped a 300mm SiPho receive function. RF Mobile also showed a sharp sequential recovery after earlier weakness.
Apr 2025The 2024 Form 20-F disclosed a landlord dispute at Fab 3 in Newport Beach. That site supports important SiGe and SiPho work, so a lease problem could have forced costly production moves.
Feb 2025SiPho reached volume production at 1.6T and strengthened the AI data center case. At the same time, RF Mobile was expected to contract in the upper teens during 2025, and ACC forecasts were reduced.
Nov 2024The initial thesis centered on fast RF Infrastructure growth from optical transceivers used in AI data centers. The offset was weak RF Mobile and delayed machine vision sensor growth.
02 Business model

Paid to run hard-to-copy wafer processes

Tower is a foundry. Customers design chips, and Tower manufactures the wafers. Its edge is not leading-edge digital logic. It is specialty analog work, where materials, process know-how, and customer qualification can matter as much as smaller transistor size.

The company earns money when customers keep wafer lines full. That makes utilization important. Empty tools hurt profit, while reserved capacity and prepayments lower the risk that Tower builds too much before customers arrive.

Tower also uses partnerships to reach larger 300mm capacity without funding every building alone. Agrate with STMicro and Albuquerque with Intel are examples. This helps capital efficiency, but it also adds partner risk when agreements change or production flows need to move.

The model breaks if customer programs shift faster than Tower can redirect capacity. That is the concern in ACC, the Intel Fab 11X dispute, and any future air pocket in data center optics demand.

03 Product portfolio

Four platforms, one clear growth engine

Growth engine

RF Infrastructure

This includes silicon germanium for electrical amplifiers and silicon photonics for optical parts. It is the center of the AI data center thesis, with 800G products in production and 1.6T products ramping.

Option

Silicon Photonics receive function

Tower is expanding SiPho beyond transmit functions with a new 300mm receive technology. Management expected production revenue from this technology to start in Q4 2025.

Steady

RF Mobile

This is mainly RF SOI for phones and connected devices. It was 24% of Q4 2025 revenue, but full-year 2025 RF mobile revenue fell 15% as Tower exited lower-margin controller offerings.

Steady

Power Management

Tower makes 65-nanometer BCD platforms for handsets, industrial, and automotive uses. The 300mm power business is growing faster than the market, helped by Albuquerque capacity.

Option

Sensors and Displays

This includes machine vision image sensors and OLED on silicon display backplanes. Tower secured its first production purchase order for Q1 2026 OLED shipments.

04 Business segments

Q4 mix shifted toward optics

RF Infrastructure32%growing fast
RF Mobile24%declining
Power Management15%modest
Sensors and Displays15%modest
Other14%flat

Segment shares use Q4 2025 management commentary. RF Infrastructure is now the largest named slice, so data center optics concentration is the key caveat.

05 Risk factors

What could break the thesis

SiPho capacity air pocket

High impact · Medium odds

Tower is building for more than 5 times its Q4 2025 SiPho shipment capacity by late 2026. More than 70% is covered by reservations or in-process reservations with customer prepayments, which lowers risk. Still, if optical module demand slows or customers delay programs, the new tools could run below plan.

We watchTrack quarterly SiPho revenue, management comments on utilization, and whether the more than 70% reservation level holds through 2028.

ACC design shift

Medium impact · Medium odds

Active Copper Cable component forecasts have been reduced. Management linked part of the issue to data center architecture changes, including shifts such as 2x36 to 1x72. This does not kill the SiPho story, but it shows how fast customer designs can move.

We watchWatch for more ACC forecast cuts and comments tied to NVIDIA architecture changes or other large AI data center designs.

Intel Fab 11X mediation

High impact · Medium odds

Intel has said it does not intend to perform under the September 2023 Fab 11X agreement. Tower is in mediation and is redirecting affected flows to Fab 7 in Japan. The risk is slower capacity ramp, extra cost, or weaker flexibility if the dispute is not settled well.

We watchWatch for a mediation outcome, any settlement cost, and updates on qualification progress at Fab 7.

RF Mobile stays weak

Medium impact · Medium odds

RF Mobile was 24% of Q4 2025 revenue, but the full-year business was down 15% in 2025. Some of that decline was planned as Tower left lower-margin controller products. The risk is that the healthier RF SOI recovery does not fully replace the exited business.

We watchTrack RF Mobile revenue growth, 300mm RF SOI demand in Agrate, and whether margins improve as low-margin work rolls off.

2028 model miss

High impact · Medium odds

Management’s 2028 target is $2.84 billion of revenue and $750 million of net profit. That is a big promise, and the stock may already price in much of the upside. If revenue ramps slower or margins do not follow, valuation could become a problem even if the business keeps growing.

We watchCompare each quarter’s revenue, net profit, SiPho ramp, and capex updates against the path needed for the 2028 model.
06 Quick answers

In one breath

Is Tower Semiconductor an AI stock?

Tower is not an AI software company. Its AI link comes from silicon photonics and RF infrastructure parts used in data center networking, where AI clusters need very fast data movement.

What is silicon photonics in plain English?

Silicon photonics uses light to move data through chips or modules. In AI data centers, it can help move huge amounts of information faster and with less power than older electrical approaches.

Why does Intel matter to Tower?

Tower uses partner fabs to add capacity without funding every facility by itself. Intel’s stated decision not to perform under the Fab 11X agreement creates execution risk, even though Tower is moving affected flows to Fab 7 in Japan.

What should investors watch next?

The biggest signals are SiPho revenue growth, progress toward more than 5 times Q4 2025 capacity by late 2026, OLED shipments in Q1 2026, and any update on the Intel mediation.