By Olivia Oran

(Reuters) - Wells Fargo & Co is set to announce a partnership with SigFig for clients to use the robo-adviser's technology and wealth management investment tools.

The announcement is expected on Tuesday, the bank said, with Wells likely to roll out a pilot version of the service during the first half of 2017.

"As we continue to invest in technology that serves the evolving needs of our clients and our advisors, this offering will mark an important step forward in delivering financial advice to the next generation of investors, while building a long-term pipeline for our full-service business," said David Carroll, head of wealth and investment management at Wells Fargo.

Wall Street banks and investment firms are increasingly building or buying robo-advisers to provide automated investment advice through web-based platforms at a lower cost than traditional financial advisers.

Unlike Betterment and Wealthfront which have focused on catering directly to young, tech-savvy millennials, SigFig has been forging relationships with banks.

UBS Group AG said in May it had bought an undisclosed stake in SigFig. The two companies also said they would form a research lab to collaborate on new wealth technology.

Wells' strategy of putting SigFig in the hands of its investing customers is different than that of UBS, which is rolling out the service for its financial advisers to help construct investment portfolios and other activities that can be automated.

Morgan Stanley and Bank of America Corp are building their own technologies, while BlackRock Inc acquired FutureAdvisor last August.

The digital wealth management market could top $20 trillion in assets by 2020, according to consulting firm A.T. Kearney.

(Reporting by Olivia Oran in New York; Additional reporting by Elizabeth Dilts and Dan Freed; Editing by Jeffrey Benkoe)