Mental health is a big business, and a growing number of tech companies are trying to tackle pieces of the problem.

On Wednesday, AbleTo, which connects therapists and coaches with patients via smartphone, said that it's buying Joyable, a provider of virtual therapy services for people who can't get access to a therapist in person.

Nearly half of the 60 million adults and children living with mental health conditions in the U.S. lack access to treatment, according to the National Alliance on Mental Illness. A shortage of affordable options has opened the door for tech companies. The global behavioral and mental health care software and services market is forecast to grow 12 percent a year, reaching $4.31 billion by 2025, according to Grand View Research.

"There's been a bunch of acquisitions recently," said Trip Hofer, CEO of AbleTo. "I see that as a recognition that behavioral health is something that needs to be addressed."

Hofer joined AbleTo nine months ago after leaving a senior role at CVS Health. A company spokesperson declined to provide exact terms of the acquisition, saying only that it was "eight figures," meaning at least $10 million.

It's been an active space. Livongo, which sells diabetes management tools to large employers, recently acquired digital mental health company myStrength, and Omada Health, a diabetes management business, licensed software assets from Lantern, a mental health coaching app.

AbleTo has raised close to $50 million in funding from strategic investors including Aetna and United-owned Optum. The company works with employers and health plans, which are looking to help workers suffering from depression and anxiety.

Data from Aetna Behavioral Health found that annual cost for treating mental health conditions is increasing twice as fast as all other medical expenses.

Hofer said that AbleTo's service has grown rapidly and now generates revenue in the tens of millions of dollars. And for patients who would benefit from a human touch, both Joyable and AbleTo have human coaches to call on for support.

"Sometimes an app alone isn't enough," Hofer said.

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