As others in this thread have already said, it all has to do with the current happenings around that Silicon Valley Bank. Circle has now officially confirmed, that 3,3 Billion $ out of their 40 Billion $ total reserves were kept at that bank and that bank is nor bankrupt. Obviously some people become nervous when they hear such news and in this case i even think it could be a proper reaction to be afraid. Then once the first people begin to sell of all their USDC at the same time the price goes down a little and this then triggers the people there were nervous but have not sold yet and they sell then too and this is kind of a vicious circle.