Vontobel has acquired the remaining 40% of fixed-income manager TwentyFour Asset Management.
Terms of the deal, which closed Wednesday, were not disclosed, according to a Vontobel spokeswoman.
Vontobel bought a 60% stake in TwentyFour in 2015. TwentyFour, which manages about 24.2 billion Swiss francs ($26.4 billion) in assets, will continue to operate independently. A message on TwentyFour's website from CEO Mark Holman said its senior management and portfolio management teams will not change.
Vontobel CEO Zeno Staub said in a news release announcing the deal that the "acquisition of the remaining 40% stake is ... the logical next step in our diversification and growth strategy."
Mr. Holman added in the news release: "After six years of working very closely together with Vontobel as a majority shareholder, the decision to move to full ownership was not a difficult one. As a direct consequence of our partnership, we have been able to spread our investment expertise to a far greater audience as we have moved from being a domestic player to genuinely global."
Vontobel had 290.6 billion francs in assets as of March 31.