SIERRA RAISES $950M AT $15.8B — BRET TAYLOR’S AI AGENT COMPANY IS NOW BIGGER THAN MOST BANKS Sierra, the enterprise AI customer service platform co-founded by former Salesforce CEO Bret Taylor, closed a $950M Series E led by Tiger Global and Google’s GV, pushing its valuation to $15.8 billion in under three years. The company hit $150M ARR in just eight quarters, with one in three of the world’s largest banks as customers. Keywords: Sierra AI funding, Bret Taylor AI startup, enterprise AI agents, AI valuation 2026