United Microelectronics (UMC) reported Q2 earnings Wednesday of 3.39 New Taiwan dollars ($0.10) per share, up from NT$0.71 a year earlier.
Three analysts surveyed by FactSet expected NT$1.02.
Operating revenue for the quarter ended June 30 was NT$68.73 billion, compared with NT$58.76 billion a year earlier.
A single analyst projected NT$67.98 billion.
Shares of United Microelectronics fell more than 4% in Wednesday's premarket activity.
Price: $16.57, Change: $-0.79, Percent Change: -4.55%