Investors question Anthropic's ability to sustain extraordinary growth amid intensifying competition and market saturation concerns. The AI startup's annualised revenue soared to $65 billion in July, with backers forecasting it will exceed $120 billion by year-end, positioning it as the fastest-growing business of all time. However, considerable uncertainty surrounds its revenue durability, reflected in a wide IPO valuation range of $1.5 trillion to $4 trillion—roughly equivalent to Amazon's current market capitalization.

The competitive landscape has shifted dramatically since Anthropic's peak. OpenAI's resurgence, particularly with the release of GPT 5.6 in July, has overtaken Anthropic in weekly customer spending for the first time in over two years. OpenAI now claims superior model capabilities with its Astra release, while both companies face pressure from cheaper 'open' models from Chinese firms like DeepSeek and Moonshot, as well as Meta. Ramp CEO Eric Glyman noted customers are switching providers based on task suitability, leading the company to slash AI spend by 40 percent.

Despite these challenges, retention data reveals Anthropic maintains a competitive advantage. Yale economist Aleh Tsyvinski found 22.5 percent of Anthropic users remain active 12 months after initial use, compared to only 13.2 percent for OpenAI. Bullish analysts argue both leading AI labs will thrive as token usage expands 250 times since late 2022, suggesting sustained demand despite commoditization pressures.