Sierra's latest raise brings total investor commitment past $1B as its AI agents expand from support into sales, retention and the full customer lifecycle. The Gist Sierra raises $950M at $15B valuation. Tiger Global and GV led the round, bringing Sierra's total capital past $1 billion and tripling its valuation from the $4.5 billion it carried just 18 months ago. From support to the full customer lifecycle. Sierra-built agents have expanded beyond order tracking and password resets into mortgage origination, insurance claims, subscription management and healthcare revenue cycle — a shift the company frames as moving from one-time transactions to ongoing customer relationships. Fortune 50 adoption backs the momentum. Sierra now serves more than 40% of the Fortune 50 and crossed $150M ARR, giving investors measurable traction to anchor a valuation that has climbed steeply in a short time.…