April 28 (Reuters) - Wealthfront will start allowing clients to invest in cryptocurrencies later this year, the U.S. digital wealth manager said on Wednesday, in the latest sign of growing acceptance of digital assets by mainstream finance.

Starting this week, users will also be able to build their own portfolio from a range of ETFs vetted by the Wealthfront team, the company said.

The moves mark a notable shift for the Palo Alto, California-based startup, whose investment strategy has traditionally been more conservative and long term, automatically allocating client assets into a set of ETF-based portfolios.

Wealthfront, one of the largest digital wealth management firms known as "robo-advisers," will also allow clients to choose from a range of socially responsible investing options, it said.

It did not specify which cryptocurrencies would be available.

Dan Carroll, Wealthfront's co-founder and chief strategy officer, said the changes reflected a growing desire from Millennial and Gen Z investors to make some investment choices, as well as a broader push by financial technology startups to provide a wider range of services within their platforms.

"Wealthfront will be the place to invest responsibly, not some Wild West arcade," Carroll said in an interview. "We can do it in a fiduciary way. We care what is in your best interests. We won't let you put 100% of your portfolio in crypto."

The company, whose services are available to people in the United States, has around 440,000 clients and assets under management of about $25 billion, according to a spokeswoman.

Its changes come amid a boom in retail trading of stocks and cryptocurrencies. Online platforms like stock app Robinhood and cryptocurrency exchange Coinbase Global Inc have seen business boom over the past year, as young homebound consumers took to buying and selling financial assets online during coronavirus lockdowns.

The popularity of cryptocurrencies has exploded in lockstep with a surge in the price of bitcoin, as more mainstream financial firms ranging from PayPal Holdings Inc and Goldman Sachs Group Inc start offering the digital asset to clients. Bitcoin is up more than 87% since the start of the year at $54,423.

Wealthfront portfolios will continue to be rebalanced automatically and users will be told what impact their investment choices have on the risk level of their portfolio, Carroll said. (Reporting by Anna Irrera in London; Editing by Jane Merriman and Will Dunham)