Coinbase reserves the right to cancel your buy before it completes. Most large transactions require a waiting period of a few days, but once you're verified and have an old enough account, you can get smaller amounts of bitcoin instantly. I just made a buy that is over the instant-buy limit, so I asked them some questions. Their answer was mostly a "please don't ask us that" kind of answer, but my questions were designed to handle that answer. Here is our exchange through the support site and emails:
Is a pending transaction susceptible to cancellation until it is completed?
Do the chances of a transaction completing go up as the few days during which it is pending go by? Is most of the risk analysis done early during the pending period, or is it done at an essentially random time before the due date?
Unfortunately we're unable to share our security processes at this time. All transactions are processed to ensure the safety and security of all users.
What this tells me is that the answers are:
- YES, pending means susceptible to cancellation.
- NO, the chances are the same until it is completed.
- It is done at an essentially random time before the due date.
I have alerted Coinbase support of this thread in case my representation isn't accurate so that they can clarify here.
