Wealthfront, the automated investment manager, announced Monday that founder Andy Rachleff is returning as CEO. Incumbent chief Adam Nash will be stepping down, but will remain on the company's board of advisors.

"For the first time, I'm actually thinking of myself as a founder first, not an investor," said Rachleff of the move in a blog post.

"I'm incredibly grateful to have had the opportunity to lead Wealthfront to the place we are today," Nash told Inc. in an emailed statement. "The question today is no longer, 'Will this work?' But, rather, 'how big will this be?' It's been an awesome journey, and I am excited for where the company will go under Andy's leadership."

Rachleff initially launched the business back in 2011, along with co-founder Dan Carroll. He served as CEO for three years before handing the reigns over to Nash, a veteran of tech firms including Apple, eBay, and LinkedIn.

"At the beginning of 2014, I was convinced that I needed to hand over my company and serve as a board member and an advisor. I was an investor, after all, not a CEO," Rachleff continued. "What I didn't realize at the time is that I'm no longer just an investor, board member or advisor. I am a founder."

Wealthfront is just one of the many firms trying to upend the way that traditional banks do business. As a so-called "robo-adviser," the company builds algorithms to help users manage portfolios of exchange-traded funds, also called ETFs. Over the past five years, Wealthfront has grown its assets under management to more than $4 billion, trailing just behind Betterment, a competing robo-adviser. In addition to managing a client's passive funds, Wealthfront offers services like direct indexing, single-stock diversification, and tax-loss harvesting. It has a minimum investment requirement of $500, and typically charges a fee of 0.25 percent annually.

As Nash told me earlier this year, the business model "does require capital." To that end, Wealthfront raised two subsequent funding rounds under his tenure, bringing the company's total capital raised to more than $100 million. Wealthfront was last valued at around $700 million.

To be sure, there are some limitations to the model. As Darrin Courtney, the principal executive advisor at CEB, a consultancy for financial firms, recently said: "Where they [robo-advisers] tend to fall short is when your true advice needs go beyond simple allocation." A small business owner would not be able to create a pension plan through Wealthfront, for example.