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Key Takeaways GlobalFoundries is expanding silicon photonics and SiGe capacity amid strong AI and data center demand.UMC is seeing stronger specialty technology demand while advancing 12-nanometer work with Intel.Both companies expect higher 2026 sales and earnings as foundry demand continues to improve. The global semiconductor foundry industry continues to benefit from rising demand for chips used in artificial intelligence, automotive electronics, industrial automation and connected devices. As chipmakers increasingly outsource manufacturing, foundries with advanced technologies, diverse customer bases and expanding production capacity are well positioned to capture long-term growth.Against this backdrop, GLOBALFOUNDRIES Inc. (GFS - Free Report) and United Microelectronics Corporation (UMC - Free Report) stand out as two prominent players. While GlobalFoundries focuses on specialized process technologies and strategic manufacturing partnerships, UMC leverages its mature-node expertise and cost-efficient operations to serve a broad range of customers. Which semiconductor foundry stock offers the better investment opportunity today? Let's compare the two.
The Case for GFSGlobalFoundries is strengthening its long-term growth profile by capitalizing on rising demand from artificial intelligence and data center applications. The company reported robust double-digit growth in its Communications Infrastructure & Data Center and Automotive businesses during the first quarter, while highlighting strong momentum in silicon photonics and silicon-germanium (SiGe) technologies. Management noted that demand for its SiGe solutions has exceeded available capacity well into 2027, prompting capacity expansion. The company also expects its silicon photonics revenues to roughly double in 2026 and target a run rate exceeding $1 billion by the end of 2028, supported by increasing customer wins and new optical networking products.
Another positive is GlobalFoundries' improving profitability and expanding customer relationships. The company posted a record first-quarter gross margin of about 29%, up more than five percentage points year over year, reflecting a richer product mix, cost improvements and contributions from higher-margin technology services. Design wins climbed 50% from the prior-year period, while strategic partnerships with companies such as Renesas and Apple reinforce its position in automotive, industrial and U.S.-based semiconductor manufacturing. Management also emphasized that its diversified manufacturing footprint across the United States, Germany and Singapore is attracting customers seeking resilient supply chains amid ongoing geopolitical uncertainty.
Despite these strengths, GlobalFoundries continues to face headwinds in its Smart Mobile Devices business, which remains the largest revenue contributor. Management expects the segment to decline at a high-single-digit rate in 2026 as the broader smartphone market weakens, although it believes the business will outperform overall industry trends. The company also warned that geopolitical disruptions could raise supply-chain costs, with additional spending on critical materials expected to weigh on margins through the remainder of the year. These challenges suggest that sustained growth in AI, automotive and communications markets will be essential to offset weakness in mobile demand.
The Case for UMCUnited Microelectronics is benefiting from improving demand across its mature-node foundry business, supported by rising utilization and strong momentum in specialty technologies. During the first quarter, wafer shipments increased sequentially, lifting utilization to 79%, while 22-nanometer revenues reached another record and accounted for 14% of total sales. Management expects more than 50 customers to complete tape-outs on its 22-nanometer platform by the end of 2026, spanning applications such as display driver ICs, networking chips and microcontrollers. Looking ahead, UMC guided for high-single-digit shipment growth and low-single-digit ASP improvement in the second quarter, reflecting healthy demand across communications, consumer, industrial and AI-related markets.
UMC is also investing to expand its long-term growth opportunities beyond traditional mature-node manufacturing. The company continues to advance its 12-nanometer collaboration with Intel, which is expected to provide customers with U.S.-based manufacturing and pave the way for commercial production in 2027. At the same time, management highlighted growing traction in emerging businesses such as silicon photonics and advanced packaging, with more than 10 customer engagements and over 35 expected tape-outs in 2026. These initiatives, combined with disciplined pricing actions planned for the second half of the year and a strategy focused on higher-value specialty technologies, should strengthen UMC's competitive position over time.
On the downside, UMC's profitability continues to face cost pressures despite improving demand. Management cautioned that higher depreciation from the Singapore fab expansion, along with rising raw material, energy and logistics costs, is expected to offset much of the benefit from stronger utilization in 2026. While the company plans to implement wafer price increases in the second half, executives acknowledged that margin expansion is likely to remain constrained until depreciation expenses begin to ease, making sustained earnings growth dependent on continued demand recovery and successful execution of its higher-value technology roadmap.
How Does the Zacks Consensus Estimate Compare for GFS & UMC?The Zacks Consensus Estimate for GFS’ 2026 sales and earnings per share implies a 7.3% and 9.9%, respectively, year-over-year increase. Moreover, in the past 60 days, earnings estimates have witnessed upward revisions.
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The Zacks Consensus Estimate for UMC’s 2026 sales and EPS implies year-over-year growth of 10.9% and 32.1%, respectively. Earnings estimates for 2026 have increased in the past 60 days.
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Price Performance & ValuationGFS stock has gained 140.2% in the past six months compared with its sector’s growth of 49.5%. Conversely, UMC’s shares have surged 247.9% in the same time frame.
Price Performance
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GFS is trading at a forward 12-month price-to-earnings ratio of 48.92X, above its median of 32.37X over the last year. UMC’s forward earnings multiple sits at 36.23X, above its median of 18.79X over the same time frame.
P/E (F12M)
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Which Stock to Buy Now?Both companies are well positioned to benefit from long-term semiconductor demand, but UMC appears to have the stronger investment case at this stage. The company is seeing broad-based improvement across core businesses, healthy momentum in the specialty technology portfolio and encouraging progress in emerging areas such as silicon photonics, advanced packaging and its collaboration with Intel.
In addition, analysts have become increasingly optimistic about UMC's earnings outlook, while it is expected to deliver faster growth than GlobalFoundries. Although both stocks trade at premium valuations after strong rallies, UMC's stronger earnings trajectory, improving demand environment and expanding technology roadmap give it an edge. This makes it the more compelling semiconductor foundry stock to buy now.
UMC currently has a Zacks Rank #2 (Buy), whereas GFS carries a Zacks Rank #3 (Hold). You can see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.