Alphabet Inc.’s Google is backing artificial intelligence developer Anthropic with a further $1 billion, building its stake in one of the most promising rivals to OpenAI.

Google has decided to invest another billion into Anthropic, four sources told the Financial Times, bringing its total sunk cost to more than three billion dollars. Both companies have declined to comment.

Google LLC, a division of Alphabet Inc., (GOOG) (GOOGL) has announced spending an additional $1 billion on the artificial intelligence startup Anthropic, a significant OpenAI competitor,

The new tranche of money from Google into Anthropic adds to a total investment of $8 billion from Amazon, the ecommerce group’s largest-ever venture investment, announced over the past 18 months. Amazon is also working to embed the Claude models into the next-generation version of its Alexa speaker.