[kasey_junk]

What about this. You just bought all of my stock of X. I have no idea if thats all you want or why you want it, but there is now less X available.

If you think the price shouldn't be impacted by that, it means something very fundamental about markets.

[Lawtonfogle]

So if X are tickets, and my plan (which you don't care about) is to now sell the tickets at 125% of the price I paid... are you saying scalping should happen?

[tptacek]

I think scalping is a really bad example of what HFTs are actually doing (see https://news.ycombinator.com/edit?id=10981812).

But scalping is an interesting example for another reason. Ticket scalping is a response to an extremely inefficient market. Scalping can only be profitable if people are willing to pay more than face value for a ticket.

It might make sense to restrict scalping for tickets, because artists might want to make tickets available to people across a wide spectrum of means. But that is never the case for tradable instruments. Restrictions on scalping deliberately seek to impede price discovery. The whole point of liquid trading markets is that the price of the instruments being traded is supposed to reflect their actual value.