So, you wanna know what is really happening? the US government are taxing those who are in possesion of bitcoins and they are being obliged to file before the first week of June. Now, here is the deal: if they appear to have no bitcoins by June, they would only be taxed for what they have earned prior. But if they have bitcoins, there will be a different computation for their taxes... that definitely caused a mass selling. Now do the math.