What is meant by investors being able "to undo" the effects of corporate restructuring?

Question

Quizplus · Accepted Answer

Investors who want to undo the effects of corporate restructuring can borrow in their own name and replicate the effects of the restructuring. For example, if a company has spun off a division that specializes in a certain area, an investor could buy stock in that division and also short-sell the parent company's stock, effectively undoing the effects of the spin-off. This strategy is known as a "reversal."

What Is Meant by Investors Being Able "To Undo" the Effects