No, they are not.
This is just the usual up and down flow of Bitcoin. This year only many times hit the floor at as low as around 300, and then the sealing at above 600. They were lot more critical times than now.
Now, it's just some panic sells, which is good. Every time after the panic sell ends, bitcoin gets stronger, as people who are buying it for this prices will obviously not be willing to sell lower. These are the times when you should buy, and hang on to it (or sell when it's above 600). December is closing fast and then price will rocket for sure for many reasons; last year it almost went as high as 1.200.
I am waiting those times. My advise is that panicked persons should sell, so they can't drag the price down again when it starts to rocket. Clever people will not sell Bitcoins at these price.