could be
there was a seller for 364,500 shares
check the GBA top 20 shareholders list
either that shareholder or some other shareholder selling a quantity of 364,500 of their holdings.
lets hope ADVENT's shale gas gets some momentum, & their next well in PEP11 is a mega success story (GBA 5c could become $1.30 duplicating a rally that "SIR" recently had).