A small Irish educational software manufacturer, taken private in controversial circumstances in 2003, is about to finalise the take over of the fourth-largest school textbook publisher in the US in a $4.5bn (£2.38bn) proposed deal.

Riverdeep, a Dublin-based company, is creating a new company to acquire Houghton Mifflin, a Boston-based publisher, for a cash consideration of $3.3bn.