Anthropic Launches Claude Sonnet 5.5 Ahead of IPO
Anthropic has launched Claude Sonnet 5.5, the second model in its Claude 5.5 family, as the artificial intelligence company expands its product lineup ahead of a planned initial public offering (IPO).
Announced on September 28, 2026, Sonnet 5.5 follows Claude Opus 5.5, which debuted on September 22. The new model targets enterprise users seeking faster, more affordable AI for everyday professional tasks.
Moreover, Anthropic positions Sonnet 5.5 as a complement to Opus 5.5. While Opus handles complex tasks requiring deeper reasoning, Sonnet focuses on routine coding, document creation, presentations and spreadsheets.
Claude Sonnet 5.5 Pricing and Features
Anthropic says Sonnet 5.5 runs more than 30% faster than its predecessor, Claude Sonnet 5. Additionally, the company claims it costs up to 30% less for most workloads.
The model retains its predecessor’s API pricing:
- Input tokens: $2 per million tokens.
- Output tokens: $10 per million tokens.
Furthermore, Anthropic says Sonnet 5.5 uses fewer tokens to complete the same tasks. Consequently, businesses could reduce overall AI costs while maintaining productivity.
The company highlights coding, bug fixing, document creation and spreadsheet development as key applications. It also emphasises improved design capabilities and performance on longer tasks.
According to Anthropic, Sonnet 5.5 scored 70.6% on Terminal-Bench 4.0, an evaluation of agentic coding. By comparison, Sonnet 5 scored 10.3% on the same benchmark.
Enterprise Growth and IPO Plans
Anthropic’s enterprise business remains central to its expansion. The company says enterprise customers account for approximately 80% of its business. Its customers include Salesforce, Databricks, Goldman Sachs and Novo Nordisk.
Meanwhile, the model launches come as Anthropic prepares for a potential public listing. Reuters reported that the company’s IPO could take place after the 2026 US midterm elections. However, Anthropic has not announced a confirmed listing date.
The company’s financial disclosures highlight both its rapid growth and substantial infrastructure commitments. Reuters reported that Anthropic generated $4.6 billion in revenue in 2025, alongside significant operating losses and planned infrastructure spending.
Additionally, Anthropic has faced growing scrutiny over AI safety. CEO Dario Amodei has called for a slower release of advanced AI capabilities to address potential risks.
Anthropic also plans to introduce Claude Haiku 5.5 in the coming weeks. The upcoming model will target fast, high-volume and cost-sensitive applications, completing the company’s planned three-model Claude 5.5 lineup.
