Wealth managers will need to improve their affluent sector offering in order to thrive in coming years, a new study suggests, as the steady rise in private wealth came to a sharp halt in 2018.

The Boston Consulting Group’s Global Wealth 2019: Reigniting Radical Growth report—now in its nineteenth year—shows personal financial wealth grew 1.6 percent in 2018 to $205.9 trillion, compared to 7.5 percent the prior year. This was below the compound annual growth rate of 6.2 percent between 2013 and 2017.

The report argues that while high-net worth individuals hold the greatest concentration of wealth (peo...