Robots are coming for retail jobs.

In-store automation threatens to kill four in 10 positions in the retail sector throughout the next decade, according to a new study.

That could add up to 7.5 million lost jobs—proportionally a much bigger hit than even manufacturing took when automation devastated its labor market, according to Cornerstone Capital Group, the bank behind the report.

It's not as if retail workers don't have enough to keep them up at night. Hundreds of store employees have lost their jobs over the past few years as online shopping and excess store space plunge the traditional retail industry into choppy waters.

Just today, Sears said it would add 30 more store closures to the 150 the beleaguered department store announced earlier this year.

Many analysts say the industry is headed for an even worse bloodbath.

In that environment, stores are looking to advances like checkout kiosks and self-returning carts to streamline operations and compete with high-tech rivals, further compounding worker woes.

In many cases, these types of new technology could replace certain roles outright, the study says.

Cashiers, for instance, are cited one of the easiest jobs in the economy to automate. That replacement in particular might disproportionately impact women, whom the study says make up three quarters of the retail cashier workforce.

The researchers write that the impact of automation is already starting to creep into the industry--something that's evident in recent headlines.

Online shopping behemoth Amazon has mapped out a host of new cashier-less physical stores, at least some of which incorporate grab-and-go checkout via an app. A New York Poststory in February suggested the entirety of each store could be run by as few as a handful of employees, though Amazon CEO Jeff Bezos cryptically mocked the tabloid's sourcing on Twitter.

Intel also announced a massive investment in retail tech earlier this year aimed at creating a licensable system that could integrate a store's basic functions into a single web-connected system. During that rollout, the company also teased Simbe Robotics' Tally, a pillar-like robot that roams through store shelves to update inventories.

While technology will ultimately ravage the retail labor market, the report says certain advances could support workers for increased productivity in the short term.

The wave of automation is part of a larger trend that could imperil the very fabric of the labor economy in years to come. A recent study estimated that half of all jobs could be replaced by technology that exists or is in development.