Aceto Corp. on Thursday night reported a loss for the October-December period compared with a profit a year earlier, on lower sales of its generic drugs.

The Port Washington-based manufacturer of drugs and chemicals said it lost $564,000 in the three months ended Dec. 31 compared with a profit of $8.3 million in the same period in 2015.

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Sales also fell in the quarter to $125.6 million, a drop of 4.6 percent from the year-ago period.

CEO Sal Guccione said Aceto’s Rising Pharmaceuticals division faced “ongoing increased competition.” He also said the recent purchase of some products from Citron and Lucid Pharma, both based in New Jersey, would expand Rising’s product portfolio.

Guccione said seven to 10 drugs will come to market in 2017 and Rising will begin selling 15 drugs acquired from Citron.

The earnings announcement came after the stock market close on Thursday. In after-hours trading, Aceto shares were down $1.76, or 9 percent, to $17.11 on the Nasdaq market.