TAIPEI - United Microelectronics Corporation (NYSE: UMC ) reported fourth quarter earnings that fell short of analyst estimates.

Despite the earnings miss, UMC shares rose 1.59% in after-hours trading following the report.

The Taiwan-based semiconductor foundry posted adjusted earnings per ADS of $0.104, missing the consensus forecast of $0.14. Revenue came in at $1.84 billion, below expectations of $1.87 billion but up 9.9% YoY.

For the fourth quarter, UMC's gross margin was 30.4%, down from 33.8% in Q3. Operating margin declined to 19.8% from 23.3% in the previous quarter.

The company said its 22/28nm portfolio remained the largest revenue contributor, accounting for 34% of wafer sales in Q4.

UMC noted customers are showing strong interest in migrating to its 22nm specialty platforms.

Looking ahead, UMC expects Q1 wafer shipments to remain flat quarter-over-quarter, while average selling prices in USD are forecast to decrease by mid-single digits. The company projects Q1 gross margin will be above 25%, factoring in impact from a January earthquake.

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