I know that it used to be a thing in the past for sure. Bit of discussion here about the phenomenon:VRS said:How comfortable is everyone with the 'predictable' weekend regular fall? It'd be very cool to work out best ways to approach it, strategy wise. I know several people who just sell up on Friday night and come back on Monday and buy lower lol!
https://bitcointalk.org/index.php?topic=63312.0