Hi Marlboro,
You ask: ...I wonder if someone has purposely unloaded a large position. Sprott comes to mind...
I look this morning at the yesterday trades on my FilghtDesk. The tango started late on the day at 15:28:06 and was orchestrated by Anonymous Broker (#001) follow by someone using the National Bank (#080) and the Jitney (#099 - platform to acomodate the active traders).
The money flow chart show that CLL was in the overbought territory (80). Buying stoped at about 13:30 and it stay dry until the selling started.
Sprott (#73) was nowhere to see. It looks like they were dancing on the different floor all day long.