The Financial Post reports in its Tuesday, April 23, edition that the question of how long Wall Street's artificial intelligence-fuelled rally will continue is a concern hanging over the tech sector this week as some of the biggest companies report their latest quarterly earnings. A Financial Times dispatch to the Post reports that the industry's big claims for the technology behind ChatGPT have spurred massive spending on the infrastructure required to generate text, images or video. However, there is not likely to be much in the numbers yet to show that the ultimate customers for the technology -- companies applying it in their operations or people using it in their daily lives -- are ready to pay up. For better or worse, Microsoft -- which reports earnings on Thursday -- has become something of a bellwether for the entire industry. Its close alliance with OpenAI Opco and early moves to embed the technology in all its software have given it a clear head start. Three months ago, Microsoft said that extra demand from AI had added six percentage points of growth to its Azure cloud platform, as customers started to test the technology. That probably translates to nearly $3-billion (U.S.) of extra revenue a year.