Your holding will change name and quantity with Aventus securityholders to receive 2.20 HDN units and either $0.285 in cash or 0.038
HMC securities per Aventus security
So 15000 AVN will result in 33000 HDN shares and the option of money ($4275) of HMC share or 570 HMC shares. The first bit will happen automatically, but you will need to decide if you want the money or HMC shares prior to the merger.