Good question, it seemed to be accomplished over a fairly short period of time without any dramatic change in share price, so perhaps some sort of arranged swap??

Speaking of price change, CLSN reports phase III results tomorrow morning pre-market - supposed to be a legitimate binary event - stock closed at 8 and halted so hardly any after hour trades. This one could be very, very dramatic, and, as always, instructional for those who invest in developmental biotech.