Insurance company Northwestern Mutual will buy financial planning disruptor LearnVest for an undisclosed sum, the companies announced Wednesday.

It may sound like an unlikely union, but it's not uncommon for fintech startups like LearnVest to be scooped up by larger financial firms eager to tap into their technology and younger customer base.

"We're shaking things up," says LearnVest founder and CEO Alexa von Tobel.

LearnVest, with offices in New York and Arizona, has made a name for itself by promising to offer financial services at a low cost to average households and refusing to generate revenue by selling customers financial products, like insurance. With Northwestern Mutual, however, it couldn’t get more old school. 

The 160-year-old Northwestern, based in Milwaukee, has 4.2 million customers, 16,000 advisors on staff and $230 billion in assets. In addition to life insurance products, the company offers investment advisory services, retirement planning, and estate planning. LearnVest is just under six years old, has a staff of 150 and operates under the mission statement “Financial planning shouldn’t be a luxury.”

Northwestern has pumped funds into fintech startups in the past, including LearnVest and Betterment, but this is the company’s first acquisition since John Schlifske took over as chief executive in 2010.

Despite her new parent company, von Tobel maintains that LearnVest's services will not change as a result of the merger. She will remain CEO and chair of the company, which will stay a separate brand from Northwestern. 

"LearnVest will still remain unbiased," von Tobel says. "Right now we’re not selling any products or making any explicit product recommendations. 

The biggest changes, it seems, will be in store for Northwestern’s advisors and clients. They will eventually be connected to LearnVest’s financial planning platform and given access to its tools, including a new feature that will show clients the impact of a financial decision on their future bottom line.

"John (Schlifske) and I have a very thoughtful multi-year plan to do some really cool things with our technology across Northwestern Mutual," she says. "I’m incredibly excited about the future."

Partnering with von Tobel will also surely be a way for Northwestern to tap into a younger generation of households. Von Tobel has always been a media darling, appearing everywhere from "The Rachael Ray Show" to the cover of Forbes magazine.

"It’s a powerful combination," Schlifske says. "You line up our products, our best field force in America and our foundation around planning, and you bring into the equation LearnVest, which makes our planning tool more engaging and more responsive and simpler."