Cloud Capex Upgrades and CoWoS Reallocation to TPU Drive 50-60% AI Semi TAM Expansion in 2027

Core Thesis

Top four US CSPs' 2026 cloud capex consensus has risen 11% post-earnings, driving a projected 75% YoY increase. This aligns with TSMC's bullish capex trajectory and confirms a 50-60% global AI semiconductor TAM expansion in 2027. Simultaneously, TSMC is reallocating more CoWoS capacity to MediaTek's TPU, raising the AI ASIC TAM forecast to $70-80bn in 2027 (from $70bn in 2028). The supply chain is tightening across TSMC wafers, CoWoS, HBM, and ABF substrates, creating a multi-year tailwind for Asian AI enablers.

Evidence Chain

Capex momentum is broad and escalating. Google raised 2026 capex guidance to $180-190bn (from $175-185bn) and flagged a significant 2027 increase. Meta lifted its FY2026 range to $125-145bn (from $115-135bn), citing memory costs and data center expansion. Microsoft guided ~$190bn for CY26 with Q4 above $40bn. Amazon reiterated $200bn for 2026. Consensus for the four CSPs now implies 75% YoY growth in 2026, up from 64% pre-earnings. Almost all CSPs emphasized ASIC strategies, echoed by Chinese CSP ByteDance working with global design service vendors. China's AI GPU demand is surging with SMIC foundry support, and Chinese CSP capex hikes are anticipated.

CoWoS allocation is shifting toward TPU and custom silicon. TSMC will allocate more CoWoS capacity to MediaTek's TPU in 2026-27. MediaTek raised its global AI ASIC TAM assumption to $70-80bn in 2027 (from $70bn in 2028). AWS Trainium CoWoS shifts to 3nm Trainium3 in 2026, with small 2nm Trainium4 possible in 2027—positive for Alchip. AMD's Venice server CPU has strong ASE/SPIL bookings, with 2026 CoWoS bookings increased from 30k to 50k wafers. The total CoWoS demand in 2026 is estimated at 1,479k wafers, with NVIDIA still dominant at 875k but Broadcom (290k) and MediaTek (40k, new entry) gaining share.

AI semi TAM expansion is underpinned by multiple product cycles. HBM consumption reaches 33bn Gb in 2026, with implied wafer revenue for AI chips at $27bn. TSMC's AI-related revenue 2024-29 CAGR could reach 60%. SoIC capacity (3D stacking) is scaling from 14kwpm in 2026e to 78kwpm by 2028e, driven by NVIDIA, AMD, and Apple.

Investment implication: The capex cycle is not peaking; it is accelerating. Companies with direct exposure to CoWoS capacity (MediaTek, Alchip, KYEC, ASE) and TPU proxies (Aspeed, Winway, MPI, Hon Precision) benefit disproportionately. The ASIC design service players (Alchip, GUC) capture rising custom silicon demand.

Key Disagreements & Risks

• CoWoS bottleneck risk: Despite TSMC's capacity expansion, demand continues to exceed supply. Any delay in equipment qualification (especially SoIC, which takes 6+ months) could constrain production and cap revenue upside for dependent players.
• Capex sustainability: Most CSPs guided for strong 2027 capex, but the 75% growth rate is historically high. A macro slowdown or AI ROI disappointment could trigger downward revisions, especially given rising memory cost components.
• Concentration risk: The TAM growth is heavily reliant on NVIDIA (59% of CoWoS demand in 2026e). A shift in GPU architecture or a faster-than-expected ASIC displacement could reshape the supply chain beneficiaries.
• Geopolitical risk: Export controls and U.S. Executive Orders (e.g., 14032, 14105) may restrict certain entities and limit growth in China's AI supply chain, affecting SMIC-linked names.

Valuation or Trade Implications

• MediaTek (2454.TW, OW, Top Pick): Direct beneficiary of TSMC's CoWoS reallocation; TPU revenue ramp provides upside to current estimates. The expanded ASIC TAM (now $70-80bn in 2027) supports a higher valuation multiple.
• Alchip (3661.TW, OW): Primary beneficiary of AWS Trainium3/Trainium4 migration and ASIC design wins. Reports May 8—catalyst for near-term re-rating.
• KYEC (2449.TW), Aspeed (5274.TWO), Winway (6515.TW), MPI (6223.TWO), Hon Precision (7769.TW) (all OW): TPU proxy plays with growing CoWoS-related test and assembly demand.
• ASE (3711.TW, OW): Strong AMD CPU CoWoS bookings (Venice) and incremental AWS allocation provide diversification beyond GPU.
• TSMC (2330.TW, OW): Structural beneficiary of all AI silicon demand; capex alignment with CSP spending confirms long-term revenue visibility.

Key metric to watch: CoWoS capacity additions vs. customer pre-payments. If TSMC's 2026 capacity (currently ~1,480k wafers) is fully booked, pricing power remains intact for the entire stack.

Appendix: CoWoS Demand by Key Customer (2026e)