The additional investment shows the enormous resources that tech companies are pouring into AI. : SEATTLE - Amazon said on March 27 that it had added US$2.75 billion (S$3.7 billion) to its investment in Anthropic, a start-up that competes with companies like OpenAI and Google in the race to build cutting-edge artificial intelligence systems. Six months ago, Amazon invested US$1.25 billion in Anthropic, making the San Francisco start-up Amazon’s most important AI partner. Amazon said at the time that it had the option to bring its total investment to US$4 billion.