Amsted received a $550-million buy-out offer.

Chicago-based Amsted Industries said the offer to take the company private was made by a group of senior managers of the firm. Under the proposal, the group and a recently formed employee stock ownership plan would pay $37 in cash and $27 face amount of subordinated discount debentures--which Wall Street sources valued at about $11 to $12--for each share of the construction and building products company.