If you're looking for a hot investment idea, Bank of America Merrill Lynch has one word for you: robots. If you're a cautious investor, the firm has two words for you: killer robots.

Illustration: Everett Collection

The firm published a massive, 300-page report on Thursday outlining the opportunities for investors in robotics and artificial intelligence. "Robots and AI are becoming an integral part of our daily lives," equity strategist Beijia Ma wrote, "as providers of labor, mobility, safety, convenience, and entertainment." The firm estimates this will be a $153 billion market by 2020, with robots performing 45% of manufacturing tasks by 2025, compared to 10% today. There are opportunities for investors in aerospace, transport, financials, healthcare, services, and mining. But, there are risks, too: robots could replace workers, robots pose cybersecurity risks, and so on. But there was one specifically that caught our eye.

Killer robots.

"We anticipate growing risks around robots," the report says, "the smart grid, autonomous or self-driving cars, and drones and commercial flights. Stakeholders are also raising legitimate, longer-term questions as to when robots/AI reaches a point that machines are truly intelligent or smarter than humans, and around the development of fully autonomous weapons." The report cites a Pew survey that found 48% on industry insiders worry about the effects of robots on society. If robots take all the jobs, for example, it risks societal upheaval and collapse.

Then there are the military drones. The firm estimates that $123 billion will be invested in drones over the next decade. But, then, who's going to control the drones, and what are they going to do with them? "The use of weaponized unmanned aerial vehicles or drones has already changed the face of warfare, but has also drawn global criticism," the report says, and mentions campaigns against the development of "autonomous killing weapons" that have included such luminaries as Stephen Hawking, Steve Wozniak, and Elon Musk.

But, that phrase, "killer robots." Makes you think of the Terminator, right? And if Stephen Hawking is worried about it, for goodness sake, shouldn't you be, too? Is the singularity near? The moment when robots become self-aware, become far more intelligent than all of us idiots wandering around playing Angry Birds?

Well, it's a risk.