Sierra, a Silicon Valley-based AI startup co-founded by Bret Taylor, former Salesforce co-CEO and current OpenAI Chairman of the Board, has secured $175 million in a new funding round, giving the startup a $4.5 billion valuation. 

This latest round, led by Greenoaks Capital with participation from Thrive Capital and Iconiq, follows an earlier $110 million funding round from Sequoia Capital and Benchmark, according to the company.

Co-founded by Bret Taylor, who is credit for co-creating Google Maps, and longtime Google executive Clay Bavor, Sierra specialises in AI-driven customer service chatbots tailored for enterprises. According to a recent Reuters report, the company's client list includes brands like WeightWatchers and Sirius XM. 

With a focus on reducing 'hallucinations', instances where AI models generate inaccurate information, Sierra aims to differentiate itself within the competitive AI customer service market, explains the Reuters report.

The funding round highlights strong investor interest in enterprise-focused AI applications, as the industry's funding emphasis moves from foundational AI models to commercialised applications.

Sierra, which has reached over $20 million in annualised revenue in its one-year run so far, is among a wave of AI firms attracting significant investment based on growth potential and the expertise of its founding team, states Reuters.