Considering that their quarterly report is just around the corner, this are probably short-sellers who are expecting (or hoping for) a negative outlook.
Also, it's above the long-term line, so at least a part of it is simply profit-taking from earlier buys.
Nope, the shape of the decrease these last 8 days doesn't look like the compulsive short reseller, the decrease is different. What people can not or doesn want to understand, is that the joycon which equip the Lite rare the same, and NO they can't fix the problem before the Lite reaches the stores, they will sell 3 to 5 millions of defect consoles, or they will cancel the launch to save their reputation of delivering good video game material.
Current PB on Secret of Mana remake : 2h27 (2nd)
Strongest worldwide achievement on TGM : 1st European S13 rank
Fastest TGM3 MASTER in Europe : rank Master V in 5min10
Western record on TGM3 EASY : 1484
Current PB on Power Ranger (Game Gear) : 10min06 (World Record)
Non-geek activity : ThermalHungary