Empirical evidence
What is the empirical evidence on how monetary policy affects inequality? In order to answer this questions, Andersen et al. dig deep into individual-level tax records, with detailed information about income and balance sheets, for the entire population in Denmark for the period 1987-2014. More specifically, they collect more than 70 million individual-yearly observations on all major components of households’ disposable income (e.g. salaries, dividends and interest expenses) as well as the main balance sheet components (e.g. housing, stocks and debt).
Our results document a strong income gradient in the gains from expansionary monetary policy: while households at all income levels benefit from a lower policy rate in terms of disposable income, asset values, net wealth and durable consumption, households at higher income levels generally benefit more. The distributional effects reflect systematic differences across income groups in the exposure to the direct and indirect channels of monetary policy. The results suggest that monetary policy has a sizeable effect on inequality: lowering the policy rate by one percentage point increases the share of aggregate disposable income by around 3.5% for the top-1% and decreases it by almost 2% at the bottom of the income distribution.

Monetary Policy and Inequality
Authors: Asger Lau Andersen, Niels Johannesen, Mia Jørgensen, José-Luis Peydró
From: University of Copenhagen, Imperial College
Who among the wealthy benefit from low interest rates
Gomez and Gouin-Bonenfant put forth a new theory on how the wealthy might be benefiting from expansionary monetary policy: even though lower rates decrease the average growth rate of existing fortunes, they increase the growth rate of new fortunes by making it cheaper for successful entrepreneurs to raise capital. In particular, they show that the overall effect of lower rates on the “thickness” of the right tail of wealth distribution depends on the types of individuals making it to the top. If, as in the U.S., individuals at the top of the wealth distribution made their fortunes as entrepreneurs, rather than investors, lower rates increase top wealth inequality. They use new data on the trajectory of top fortunes for the top 100 individuals in the U.S.:
We use a sufficient statistic approach to quantify the effect of lower rates on top wealth inequality. Our preferred estimate is that a permanent one percentage point decline in discount rates generates a decrease in the Pareto exponent of the wealth distribution by −2.7%. To put this estimate into perspective, this suggests that the 4% decline in discount rates over the 1985-2015 period can account for roughly two-thirds of the decline in the Pareto exponent during the time period.
A Q-Theory of Inequality
Authors: Matthieu Gomez, Émilien Gouin-Bonenfant
From: Columbia University