At stores like Walmart, what happens to brand-name products if they
aren't sold? Does Sony, Toshiba, Microsoft, and others buy them back
at no loss to the discount stores? Thanks for your expertise.

I have no expertise, but as an ex-retailer, I would point out that
there are two general methods of purchase for retail. 1) Simple
purchase where the buyer owns the goods and disposes of them as they
see fit. 2) Sale-or-return, where the buyer has the option to return
unsold goods within a specific time-frame. Sale-or-return would
normally be the more expensive option (ie. the cost per items sold
would be higher). Large stores may well have the purchasing power to
generate their own deals with suppliers of a sale-or-return nature
without any financial penalties. It's all speculation, but for what
it's worth...those are my comments