ASE Technology vs. Amkor: Which Chip Packaging Stock Is the Better Buy?

Artificial intelligence (AI) and high-performance computing are driving unprecedented demand for advanced semiconductor packaging, making outsourced semiconductor assembly and test (OSAT) providers increasingly important to the semiconductor value chain. ASE Technology Holding ASX and Amkor Technology AMKR are two global leaders benefiting from this trend, with both reporting strong first-quarter 2026 results and expanding their advanced packaging capabilities.

While both companies are well-positioned to capitalize on the AI-driven packaging cycle, differences in their growth outlook, profitability and earnings trajectory could determine which stock offers superior long-term returns. Let's dive deep and closely compare the fundamentals of the two stocks to determine which one is a better investment now.

The Case for ASE Technology Stock

ASE Technology continues to strengthen its leadership in advanced semiconductor packaging as AI demand reshapes the industry. The company reported first-quarter 2026 revenues of NT$173.7 billion, up 17% year over year, while its Assembly, Testing and Material (ATM) business delivered record revenues of NT$112.4 billion, increasing nearly 30%. Even during a seasonally weak quarter, ATM revenues grew sequentially as demand for AI-related products remained exceptionally strong. Gross margin expanded to 20.1%, and operating income jumped 81% year over year.

AI has become ASE Technology's biggest growth engine. Management noted that AI workloads are reducing the traditional seasonality of the packaging business, with strong demand across LEAP advanced packaging, traditional advanced packaging and wirebond solutions. Computing applications continue to represent a growing portion of revenues as AI accelerators, high-bandwidth memory and advanced processors require increasingly sophisticated packaging technologies.

To support future demand, ASE Technology continues to expand LEAP capacity despite higher near-term depreciation expenses. Management expects newly installed production lines to ramp up primarily during the fourth quarter, supporting sequential margin expansion through the remainder of 2026. The company also benefits from its integrated packaging, testing and EMS operations, diversified customer base and improving factory utilization, all of which strengthen its competitive position.

The primary risks stem from elevated capital expenditures, higher depreciation during capacity expansion, foreign exchange volatility and geopolitical uncertainties. Nevertheless, these appear manageable considering the robust structural demand for AI packaging.

The Case for Amkor Stock

Amkor has also entered 2026 with considerable momentum. First-quarter revenues reached a record $1.68 billion, increasing 27% year over year as broad-based demand lifted every major end market. Improved factory utilization, growing advanced packaging programs and disciplined execution helped earnings per share climb to 33 cents from 9 cents a year ago.

Advanced packaging remains the centerpiece of Amkor's long-term strategy. Management continues investing heavily in HDFO, flip-chip packaging and advanced testing technologies to support AI servers and data-center processors. Several AI-focused customer programs are expected to ramp up during the second half of 2026, while the company believes advanced packaging will remain its primary long-term growth engine.

Amkor is simultaneously expanding its manufacturing footprint. Construction of its advanced packaging facility in Arizona remains on schedule, while additional manufacturing capacity in Korea will support growing AI infrastructure demand. These investments strengthen relationships with leading semiconductor customers seeking geographically diversified supply chains.

However, Amkor's investment cycle also creates challenges. The company expects capital expenditures of $2.5-$3 billion this year, which will pressure free cash flow in the near term. Export controls, geopolitical uncertainty, supply constraints involving advanced silicon and substrates, and rising material costs also remain important execution risks.

ASE Technology Leads the Performance Race

Both stocks have significantly outperformed the broader semiconductor industry this year as investors increasingly favor AI infrastructure beneficiaries. ASE Technology shares have surged 149.8% year to date, comfortably ahead of Amkor's impressive 99.4% gain. Both stocks have substantially outperformed the Zacks Electronics-Semiconductors industry's 48.6% return, the Zacks Computer and Technology sector's 13.1% gain and the S&P 500's 7.2% advance.

ASX vs AMKR Price Performance (YTD)

The strength extends across semiconductor infrastructure stocks. Applied Materials AMAT and KLA Corporation KLAC have also benefited from AI-driven semiconductor investment and advanced manufacturing demand, rising 143.9% and 104.6% YTD, respectively. However, ASE Technology has delivered the strongest stock performance among this group, highlighting investor confidence in its AI packaging growth strategy.

ASX vs AMKR: Valuation Comparison

Following their strong rallies, both stocks trade at premiums to the industry average. ASE Technology currently trades at 35.33X forward 12-month earnings, slightly below Amkor's 37.11X, while the Zacks Electronics-Semiconductors industry trades at 33.61X.

ASX vs AMKR Valuation (P/E F12M)

Compared with semiconductor equipment leaders AMAT (42.78X) and KLAC (50.18X), both ASE Technology and Amkor continue to command healthy valuations as investors increasingly recognize advanced packaging as one of the fastest-growing segments of the semiconductor supply chain. Even so, ASE Technology offers the more attractive valuation of the two while also providing stronger projected earnings growth.

Analysts Continue Raising Earnings Estimates

Analysts have become increasingly optimistic about both companies, though ASE Technology enjoys stronger long-term growth expectations.

Over the past 60 days, the Zacks Consensus Estimate for ASE Technology's 2026 earnings has increased to 84 cents per share from 77 cents. Analysts expect earnings per share (EPS) to grow 47.4% on 19.6% revenue growth this year, followed by another 73.2% earnings increase on 22.4% revenue growth in 2027.

ASX Estimate Revision Trend

Amkor has also witnessed positive estimate revisions, with the Zacks Consensus Estimate for 2026 EPS increasing to $2.08 from $1.94 over the past 60 days. Analysts currently expect 38.7% earnings growth on 13.2% revenue growth in 2026. However, growth is projected to moderate sharply in 2027, with EPS expected to increase just 3.7% on 9% revenue growth.

AMKR Estimate Revision Trend

ASE Technology's stronger earnings trajectory reflects its larger exposure to AI-driven advanced packaging and suggests greater operating leverage as new capacity ramps.

Which Stock Offers Better Upside?

Both ASE Technology and Amkor stand to benefit from the rapid expansion of AI infrastructure, advanced chip architectures and increasing semiconductor packaging complexity. Both companies delivered impressive first-quarter results, continue investing aggressively in advanced packaging capacity and maintain strong relationships with leading semiconductor customers.

However, ASE Technology currently appears to be the stronger investment. The company offers faster revenue growth, superior margin profile, stronger AI-driven ATM momentum, a slightly lower valuation and meaningfully better long-term earnings growth expectations. Its expanding LEAP platform and improving profitability further strengthen its competitive position as AI packaging demand accelerates.

Amkor, having a favorable Zacks Rank #2 (Buy), remains a compelling long-term semiconductor packaging company with solid execution and expanding global capacity. Nevertheless, ASE Technology's stronger fundamentals and better earnings outlook give it the edge as the better chip packaging stock for investors seeking greater upside from the ongoing AI infrastructure buildout. ASE Technology currently sports a Zacks Rank #1 (Strong Buy). You can see the complete list of today’s Zacks #1 Rank stocks here.

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