Except stock price is supposed to indicate discounted future expectations of value. I expect that they will spend that $1B in the future with little to show for it.
For comparison, though, "Reebok" is really just the Reebok brand. I mean, I'm assuming all of the production of the actual shoes is outsourced to some sweatshops like all the other shoe manufacturers. Even the article refers to Reebok as "the U.S. brand management firm".