There was no market place. Just fifo queues of people willing to buy tickets, and tickets for sale. that constantly works its way down to atleast one of them being 0.

I signed up for the main concert and a few of the after parties, and over the next month I got emails saying I had purchased tickets for the various events.

If that's the case then it doesn't solve the problem of wanting to take a different friend, unless there are plenty of tickets available.