Waffer Technology (TPE:6235) posted revenue of NT$523.9 million for May, down 1.6% from NT$532.2 million a year earlier, according to a Tuesday Taiwan Exchange filing.
For the first five months of the year, cumulative revenue rose 3.7% year-on-year to NT$2.68 billion, the wafers manufacturer said.
Shares fell over 3% on Tuesday's close.