Gerdau (GGB) reported a Q4 loss late Monday of 0.66 Brazilian real ($0.13) per share, swinging from earnings of 0.15 real a year earlier.
Analysts polled by FactSet expected 0.39 real.
Net sales for the quarter ended Dec. 31 were 16.97 billion reais, up from 16.82 billion reais a year earlier.
Analysts surveyed by FactSet expected 16.35 billion reais.