Goldman Sachs is buying boutique wealth-management firm United Capital Financial Advisers for $750m in cash, striking its biggest deal in two decades as it accelerates a push away from Wall Street into lower-octane businesses.

United, whose 220 financial advisers manage $25bn in assets, will slot into Goldman’s existing wealth-management business, which skews toward billionaires. The Wall Street Journal reported last week that the companies were nearing a deal.