While their share prices have traveled different paths recently, the similarity between the two companies is striking. Altimmune (ALT 4.15%) and Viking Therapeutics (VKTX 4.41%) have a lot of features in common, but, at least for the moment, the performance of their stocks is not one of them. Whereas Viking's shares are up by 610% over the last three years, Altimmune's are down by 54%. However, there's more than one argument for why Altimmune's next act could look a lot more like Viking's trajectory. So let ...