Affiliate Trademark Bidding
There are a lot of ways that companies approach this issue. Generally the bigger brands do not allow affiliates to bid on the brand names, and they only permit affiliates to bid on generic terms.
Some other affiliate programs grant special consideration to a select group of affiliates to bid on the trademarked terms, and then there are affiliate programs that have a free for all when it comes to bidding on trademarks.
In my opinion, if you have a big brand you should not permit affiliates to bid on trademarked terms. This is something the merchant can easily do themselves, and affiliates that solely bid on trademarks are not bringing any value to the table.
That said, it’s fairly common for some of the bigger ppc affiliates to get permission to bid on trademarks, because they’re bidding on a large volume of words for the merchant.
The reasoning here is that the affiliate is taking a risk and loss on some of those words and the trademarks balance out some of that risk.