The richest 1% of America's households own 40% of the country's wealth – the biggest proportion in 50 years, according to a new paper by economist Edward N. Wolff.

The research, reported on by the Washington Post, also suggests that the country's top 1% have more wealth than the bottom 90% of households combined. The wealth gap has widened in recent decades, with the share of wealth owned by the richest 1% growing by nearly three percentage points since 2013 alone.