Nathaniel David is an American scientist and entrepreneur who co-founded a series of technology companies in the biotechnology and sustainable energy sectors, including Syrrx (acquired by Takeda Pharmaceutical Company), Achaogen (NASDAQ: AKAO), Kythera Biopharmaceuticals (NASDAQ: KYTH, acquired by Allergan), Sapphire Energy and Unity Biotechnology.These companies have collectively raised more than $1.5 billion in financing.