This could be a double edged sword. Someone trading KDC on Mintpal has about 3 BTC to play with and they'll pull that wall when the price has raised high enough to dump for a profit. They usually use a couple of walls of about 1.5 btc to simulate buy support. Once they've dumped half, they'll chuck in a sell wall to keep the price down to buy back in cheap.

It could also be a new player, but it follows the same pattern as it has over the past few days.