Wall Street is hyping AI. This fund manager is betting instead on fires, HVAC and Berkshire Hathaway.

A Heartland Advisors co-portfolio manager is pushing back against Wall Street's enthusiasm for artificial intelligence, arguing that investors may be better served by looking beyond the companies generating the most AI hype. His alternative focus: unglamorous, cash-generating businesses such as fire protection and HVAC services, alongside Berkshire Hathaway.

The logic rests on how technology diffuses through the economy. Rather than trying to pick which AI developer wins, the argument goes, investors could examine companies that stand to benefit by adopting AI tools as their costs decline—using the technology to improve margins in businesses whose underlying demand is steady and less dependent on the tech cycle.

For market observers, the comments highlight a recurring debate in any technology boom: whether the durable returns accrue to the builders of a new technology or to the broader economy that eventually puts it to work. What to watch is whether AI adoption costs fall enough to show up in the operating results of traditional, less-hyped industries—and whether investors rotate toward them if that happens.