The spread between the two products for the week ended 19 August was 9.23 cents/lb ($203/tonne), compared with 11.74 cents/lb the prior week. The spread is at its narrowest point since 8.84 cents/lb in the last week of December.
US spot benzene prices have been supported by limited imports in recent months. The benzene market is structurally short and relies on imported material to meet consumption.
In April, benzene imports were at their lowest monthly level and were nearly as low in June, according to the most recent US International Trade Commission (ITC) data.
Market sources have said benzene imports have remained scarce through August.
Spot styrene prices were in a lower range for the week, further tightening the spread. However, spot styrene prices closed the week on an upward trend, largely due to upstream benzene and crude oil increases.