Formosa Plastics' (TPE:1301) consolidated sales fell 2.7% annually to NT$14 billion in June, according to a Thursday Taiwan Exchange filing.
The company said lower shipment volumes, driven by reduced operating rates and cautious customer purchasing, more than offset higher product prices.
Average selling prices remained above year-ago levels following the earlier rise in crude oil and petrochemical prices during the U.S.-Iran conflict.
Monthly, June sales declined 6.5% as easing Middle East tensions and the reopening of the Strait of Hormuz pushed down crude oil, naphtha and petrochemical prices.
Higher caustic soda shipments partly offset the monthly decline, the filing said.