The company reported an adjusted net loss of $57 million, or 31 cents a share on revenue of $2.4 billion.
Alcoa had been expected to report a loss of $42.7 million, or 21 cents a share, on sales of $2.5 billion, based on a FactSet survey of 11 analysts. In the same period a year ago, the company posted earnings of 66 cents a share on sales of $3.3 billion. It reported a loss of $6 million.
Shares fell 53 cents, or 2.6%, to $19.65 in after-hours trading after earlier rising slightly.
In the upcoming quarter analysts are forecasting a loss of $0.6 million, or 6 cents a share, on sales of $2.5 billion.