Demand for a key ingredient in a sought-after Covid-19 treatment drove a busy year for Ligand Pharmaceuticals. The biopharma maker was also active on the deal front, continuing a recent spate of transactions. In October, Ligand Pharmaceuticals Inc. (Nasdq: LGND) completed its acquisition of Pfenex Inc. for $437.5 million in cash, plus a contingent payment of $78 million in cash if milestones are met. Pfenex owns a proprietary technology used to produce enzymes, peptides, antibody derivatives and engineered non-natural proteins.