It is trading as HGGDA. Further code changes are ahead as it becomes a CDI of NY listed Janus Henderson. There is an ASX announcement of codes and timetable on the ASX website and eTrade's HGGDA news.
The 5% price hike today is likely due to the alignment of HGG CDI to the Janus NY share price - though I have not found the Janus NYSE listing. I have not looked very hard.
I anticipate (want) further rerating as the merger settles down and the benefits become clear.
Ash
HGG Price at posting:
0.0¢ Sentiment: Buy Disclosure: Held