Can't really agree with that. Sometimes the business can come up with mutually beneficial solutions. Of course in general the rule is just as you describe it - each intermediary add the costs.
However, let's look at it this way. IB is a well known provider of brokerage services, yet I've heard that some customers really hate their support. Others dislike it for some other reasons.
It can happen so that some other company is eager to become a partner for IB on this matter. They get discounts from IB and resell the service at the price that can be found fair enough for them to meet the ends.
Even if they do more service for little money, they still get some benefits in terms of marketing. I.e trade.com offers subscriptions to their algorithmic strategies, etc. that they can sell along with DMA.
However, let's look at it this way. IB is a well known provider of brokerage services, yet I've heard that some customers really hate their support. Others dislike it for some other reasons.
It can happen so that some other company is eager to become a partner for IB on this matter. They get discounts from IB and resell the service at the price that can be found fair enough for them to meet the ends.
Even if they do more service for little money, they still get some benefits in terms of marketing. I.e trade.com offers subscriptions to their algorithmic strategies, etc. that they can sell along with DMA.