Operating margin expansion from 2.4% to 11.3% over the same span outpaced gross margin growth, which is consistent with a high fixed-cost cleanroom and depreciation base being absorbed by higher volumes rather than with pricing power. Net margin of 9.6% appears the more honest read of current earning power, though the sequential rebound in SG&A to $99.0M from $78.9M and the sharp FCF swing from -4.7% to 24.5% between 2026Q1 and 2026Q3 suggest part of the reported strength is timing-sensitive and should be tested against a full-cycle average.

The improvement in ROIC from the 0.5% trough in 2025Q1 appears almost entirely margin-driven, since asset turnover moved only from 0.19 to 0.20 over the period and actually sits below the 0.27 recorded in 2024Q3, implying the denominator is growing faster than the sales it supports. ROE of 4.0% exceeding ROIC of 2.9% reflects the rising debt contribution to equity returns rather than operating outperformance, and investors should monitor whether the newly commissioned capacity converts into sustained turnover before depreciation charges begin compounding.

The DIO build is the dominant driver, which may reflect pre-build ahead of advanced packaging ramps or simply slower legacy inventory turns, and it warrants scrutiny against consigned-versus-purchased material disclosures before being read as demand strength. DPO extension to 51 days from 45 shows suppliers are partially financing the build, while DSO at 68 days versus 62 a year earlier suggests customer collection has not kept pace with revenue growth, a combination that pressures operating cash conversion when volumes soften.

The sharp leverage increase concentrated between 2026Q1 and 2026Q2 alongside a 45% growth in total assets implies the borrowing was directed at capacity rather than at bridging operating shortfalls, which is a defensible use of balance sheet capacity if utilization sustains above the levels seen in 2025. However, the D/EBITDA reading of 11.35x in 2026Q3 versus 6.71x sequentially appears inconsistent with the improving coverage ratio and may reflect quarter-specific EBITDA volatility, so investors should monitor trailing-twelve-month leverage as new plants ramp while fixed costs pre-exist revenue.

The 8.41x EV/EBITDA falling to 6.07x forward, against ASE at 25.50x, indicates a substantial discount that may reflect either Amkor's lower ROIC of 2.9% versus ASE's 7.6% or a market skeptical that the 18.3% gross margin is sustainable through a full cycle. P/B of 2.03 looks modest next to ASE's 7.71 but is only justifiable if returns on equity converge toward the peer's 16.1% rather than the 4.0% currently delivered, while P/FCF of 47.88 appears inflated by an unusually heavy capex year rather than by rich equity pricing.