Robo-advisors are apparently here to stay—that is, if Betterment has anything to say about it. The independent robo-advisor has become the first to reach $5 billion in assets under management.

The trend in robo-advisors – online algorithm-based portfolio management advice — has been steadily growing, as the services and options they offer increasing and conventional advisors seeking to add robo options to their own offerings, both in regular investing and in retirement saving. In March, for instance, Betterment added account aggregation to its platform to enable its clients to improve their retirement preparedness; that was after a January launch of its 401(k) platform Betterment for Business.

That doesn't mean that robo-advisors are risk free.