the purchase price or rather ratio of .1042 shares of argo for each share of pdg was based on the 20 days previous sp. as the share price of argo moves so does pdg. Given that ar ius now trading at higher prices than the 20 days prior to announcement it makes snese that pdg would follow.
ar is trading around 10.95 so pdg should be around .1042 of that or 1.14