Ethylene fell slightly because of a drop in spot prices, which more than offset an increase in ethane costs, sources said.
The US ethylene contract usually settles at the beginning of the month for the previous month.
Major US ethylene producers include Chevron Phillips Chemical, ExxonMobil, INEOS, LyondellBasell and Shell Chemicals.
Buyers include Dow Chemical, Georgia Gulf, Occidental Chemical (OxyChem) and Total.
($1 = €0.73)