There are people who drop prices of alt.currencies intentionally. From what I remember seeing on exchanges, I can make real conclusion: somebody intentionally work on drooping prices, they even put big money in it.
Who else has noticed? Who are "they" and why they do this? Maybe ASIC owners?
it can be any speculant with lot of BTC; or it can be just "us" - all wanting dump coin that we all know are quite useless