I believe mostly related to MTgox selling lots of bitcoins and causing fear that he may sell more (which you can best rest assured he will not, as the next court appointment is at the end of the year). Also, there's a meeting in the US I believe Wednesday, where they will discuss Exchange regulation and ICOs.
It could be, but there are lots of things that are shaping Bitcoins price.
And this time of the year is usually the bear market or value drop.
The market is in a downward trend to adjust before the stronger growth in the mid-year. Bitcoin can be very profoundly reduced so that many new investors can enter the market and that is the motivation for other altcoin to grow stronger.