Nowadays bitcoin market cap is
155Bln, and was more a few weeks ago
400Mln represents
0.26% of it
It didn't has much impact on the price
That is simple and effective mathematic logic...
not that simple. A sudden influx of 400mln causes many weak hands to fold, which increases the amount. This effect keeps on perpetuating itself, dragging the price down.
bitcoin is know for is high volatility, it is usual for it to do +/- 5% moves in less than one hour. We see this several times in a day