Microsoft stock sinks as new AI rival targets $27 billion business

This article first appeared on GuruFocus. Shares of Microsoft Corp. (MSFT, Financials) slumped 2.2% after the artificial intelligence company AnthropicI9O unveiled a spreadsheet tool that might compete with one of Microsoft's oldest commercial apps, Excel.The news targets another popular Microsoft product as the corporation seeks to grow beyond its current AI offerings.Excel has been a staple of Microsoft's productivity software business for a long time, used by individuals and businesses that rely on spreadsheets for financial analysis, reporting and day-to-day work.The arrival of fresh AI tools into the market raises issues about how users develop and manage spreadsheets, and if that will alter.