Producers of wide-flange steel beams are moving to keep prices steady in the face of a falling raw material index, lagging demand and offers on the street that continue to undercut official mill tags.

Nucor-Yamato Steel Co. said that, in line with a corresponding drop in a benchmark scrap price, it will bring its raw material surcharge down by $25 per ton on Dec. 1 to $73 per ton. At the same time, the Blytheville, Ark.-based producer will raise its base price by $25 per ton in a move that "will result in no...