Prices in the global petrochemicals market kept falling in September, following the drop in prices upstream, according to the recently released Platts Global Petrochemical Index. The September index was down by $43, or 3%, from the August price of $1,427 per metric ton. On a year-over-year basis, petrochemical prices were less than 1% lower than in September 2013.

Olefin prices fell slightly in September. Ethylene and propylene prices both fell by 1% from the previous month, mostly due to decreasing naphtha prices. Polyethylene also saw a price decrease of 3% in September, while polypropylene prices dropped by 2%.

“There were two factors contributing to lower prices in the petrochemical markets this past month,” said Jim Foster, Platts’ editorial director of petrochemical analytics. “First, both crude oil and naphtha prices have been falling. This has reduced the cost of making petrochemical products. Second, the prices of petrochemical products have climbed too high for buyers, resulting in a fall in demand and slower sales.”