[flignats]

They do update that price frequently (minutes, maybe seconds) and there is a premium added to the price. I assume they add this premium so they can then go liquidate it for profit on the exchange as needed.

[coralreef]

That doesn't sound to you like they're just selling it on gdax?

[flignats]

They can do whatever they want with it after they have sold it to me for a fixed price.

[coralreef]

Heh, I'm not sure why you think its a fixed price. They're probably showing you the lowest sell order on the order book.

[flignats]

Have you ever bought/sold on CB? It is exactly that, a fixed price. It's the convenience you pay for to use CB. That price updates frequently, but whatever price you execute at is the price you pay/sell for.