AI is shaking up a lot of things-including which stocks investors can expect to hold up in a market selloff.

Investors have long relied on a mathematical measure known as beta to judge market risk. A stock with a beta of 1 tends to move in line with the stock market. A score of more than 1 suggests larger market-related swings, while a score of less than 1 suggests a calmer ride. A stock (or other investment) with a negative beta tends to move in the opposite direction of the market.

Lately, however, something strange appears to be going on with market beta, according to a recent note from Trivariate Research. The number of stocks with negative betas has surged to 28% from less than 10% over much of the past two decades-and AI is the reason.

"Beta dispersion is at an all-time high," wrote Trivariate founder Adam Parker on Sunday. "AI and non-AI stocks are behaving like separate markets."

The dynamic suggests good news and bad news for investors. The good news is that in an AI selloff there should be plenty of places to hide, with many stocks likely to hold up or even rise as AI stocks sell off.

The bad news is that investors may need to rethink which stocks will be their defensive go-tos, since some traditionally low-beta stocks have now become part of the AI trade-think professional services companies like Accenture, Equifax, and ManpowerGroup, according to Trivariate.

Among the sectors showing the most negative beta in recent months-meaning they have tended to move in the opposite direction of the broader market-are insurance, food, beverage & tobacco, utilities, and energy.

Among those, insurance may come as something of a surprise. There's been no shortage of speculation about how AI could reshape the insurance industry, from helping insurers use reams of data to spot underwriting risks to automating claims and other customer service tasks.

In an interview, Parker speculated that the sector's recent negative beta reading could simply reflect an industry that is struggling in an otherwise strong market. While insurers steadily hiked premiums starting in 2022, they recently shifted toward more aggressive pricing to capture market share, which could translate into lower profits.

"Premium rates are softening across multiple lines, particularly personal auto and commercial property," explained a report earlier this summer from Boston Consulting Group. "Casualty lines face their own challenges. The cost of losses, driven by such factors as social inflation, severe convective storms, and elevated claims severity, remains high."

A better bet for investors looking to protect against an AI selloff may be energy. AI adoption is expected to be a long-term driver of returns for energy stocks-given all the electricity AI uses. But recently, these stocks have been trading on events in the Middle East. Given that, it's not hard to see why they are moving in the opposite direction of the rest of the market-flare-ups around the contested Strait of Hormuz tend to boost oil prices, good news for energy stocks but bad news for much of the rest of the market.

Barron's highlighted a number of energy stocks with negative betas in June. Names included Exxon Mobil, Chevron, ConocoPhillips, EOG Resources, Diamondback Energy, and more.

Since energy stocks tend to be volatile and come with their own set of risks, Trivariate also screened for non-energy names that show low beta and low correlation to AI. Among these: tobacco company Altria Group, utility Consolidated Edison, grocer Kroger, and capital markets firms CME Group and Cboe Global Markets.