I believe it was someone moving shares to a more tax friendly account. ie they are thinking the price is only going up and up. It's sort of a dangerous move. Someone could steal these shares by having a limit open order at a low price, but is shows people are getting ready for November
I am sure that was a sell at the "market" price which is a very unprofessional option to sell SECI shares.
Why? Because the folks that buy and sell on behalf of the brokers can set their own bid at $15 or even less and buy at that price from someone who is selling SECI at "market" price and then sell those shares back at much higher price. That is why the SECI bid and ask should always be done as "limit" price.