ASE and KYEC: AI Back-End Demand Driving Above-Guidance Growth and Margin Expansion

Core Thesis

ASE (3711.TW) and KYEC (2449.TW) are positioned for revenue and earnings upside surpassing current guidance, driven by structural overflow demand from TSMC for advanced AI packaging and longer-than-expected testing times for new AI ASICs. Our analysis points to 2026 AI revenue of $3.5bn for ASE (vs. guidance of >$3.2bn) and higher revenue for KYEC from MediaTek's TPU, supporting raised price targets of NT$408 and NT$358, respectively. The investment case rests on underestimated pricing power, capacity expansion, and the quality of AI-driven mix shift.

What the Market May Be Missing

The market appears to be underappreciating the scale of non-TSMC advanced packaging demand and the associated pricing power. For ASE, the focus has been on its substrate (oS) business for NVIDIA, but overflow demand for full CoWoS-like packaging for AMD's Venice CPU and Google TPUs is a new, higher-value growth vector. For KYEC, consensus may not fully price in the revenue impact of longer final test times for MediaTek's TPU, which are 20% higher than initial expectations at 500-600 seconds, plus a four-hour burn-in.

Evidence Chain

ASE's LEAP revenue forecast of $3.5bn in 2026 is underpinned by multi-client overflow demand. A bottom-up product build-up supports this figure, exceeding management's $3.2bn guide. Demand is bifurcated: oS outsourcing for NVIDIA (nearly 100%), Google TPU (70-90%), and AMD MI400 (80%); and full CoWoS-like packaging for AMD's Venice CPU. The dollar content per chip for Venice packaging at ASE is estimated above $300, contributing materially from 2026. This diversification beyond NVIDIA reduces customer concentration risk and taps into a broader AI accelerator market.

KYEC's AI revenue stream is bolstered by elongated test times for key ASIC programs. MediaTek's TPU, on track for 4Q26 production, now requires 500-600 seconds of final test time, up from an initial 450-second assumption. This, coupled with KYEC's likely role as the primary test service provider for this chip, drives upside to 2027-2028 estimates. AI-related demand is projected to reach ~40% of KYEC's total revenue in 2026, supporting a corporate gross margin profile nearing 40%.

Capacity expansion and pricing dynamics support sustainable margin accretion. Non-TSMC CoWoS capacity (including ASE's) is forecast to nearly double in 2026, capturing demand TSMC cannot fulfill due to clean room limitations. This tight supply environment for advanced back-end services grants pricing power. For ASE, ATM pricing is likely to rise 5-20% in 2026. For KYEC, the mix shift towards longer-test-time AI products drives higher utilization and improves the margin structure.

Key Divergences and Risks

• Execution on New Platforms: Any delay in AMD's Venice CPU or MediaTek's TPU ramp could impact the timeline of revenue recognition. An engineering change order (ECO) for the MediaTek TPU is noted, though a full re-spin is not currently expected.
• Competitive Dynamics: While ASE is a primary beneficiary of TSMC's overflow today, longer-term competition from other OSATs (e.g., Amkor, UMC) in non-TSMC CoWoS could intensify, potentially pressuring margins.
• Macro Demand Swings: A broad-based slowdown in semiconductor demand outside of AI could partially offset the strong growth in these targeted segments, though the relative exposure is lower for these firms.
• Valuation Re-rating Halt: Stocks are pricing in high growth. Failure to meet elevated expectations or a sector-wide de-rating could limit multiple expansion.

Valuation and Trading Implications

We raise our price targets for ASE to NT$408 (from NT$368) and for KYEC to NT$358 (from NT$348). These targets imply 17x and 23x our 2027e EPS, which we view as attractive given 2025-28e revenue CAGRs of 24% for ASE and 38% for KYEC. The valuation premiums are justified by superior growth visibility, elevated AI exposure, and improving margin profiles. Both stocks offer a compelling way to gain exposure to the secular AI infrastructure build-out through the often-overlooked but critical back-end supply chain. Accumulation on dips is advised.

Appendix: Key Data Summary