Sierra - the startup of Bret Taylor, former co-CEO of Salesforce and current chairman of OpenAI's board - is raising a new round of 950 million dollars led by Tiger Global and GV. With this, the company's valuation crosses 15 billion dollars, and there is more than 1 billion dollars of cash on hand to work with.

That's a huge sum for a four-year-old startup, but the revenue numbers justify the move. Sierra hit 100 million dollars in annual recurring revenue in November last year, and just three months later, in February, the number jumped to 150 million. Exponential growth isn't a myth - Sierra claims it already has more than 40 percent of the Fortune 50 as clients.

What does the platform actually do? Agents that handle billions of interactions - refinancing mortgages, processing insurance claims, managing product returns and running campaigns for non-profits. In other words - Sierra wants to replace corporate contact centres with AI agents that don't „respond from a script," but solve whole tasks end to end.

At a recent StrictlyVC event, Praveen Nepali Naga, Uber's CTO, described how the company „blew the AI budget" once it opened the door to agent tools. Around 10 percent of their code is now generated autonomously across about 8,000 engineers. One team finished an integration for hotel reservations in 6 months - a project that would usually take a year. That's the figure investors read as a signal that the market is maturing.

Taylor has previously said that the best outcome of agent AI is lower costs and higher revenue at the customers - but the „pumping" phase is expensive. That's the diplomatic way of saying - it's still expensive, and it takes time. The question for the next 18 months isn't whether Sierra has clients - they already do, and enough of them - but whether they can keep up 50 percent growth in three months without losing service quality. The Balkan company that thinks it'll compete with Sierra on price will lose. The one that thinks it'll compete by specialising in a particular industry - might have a shot.