A recent academic study looking at the performance of IRAs found some "striking and unexpected" results. First, for those who make less than $200,000 (or "low-income"), returns on Roth IRAs were 3.6% from 2004 to 2018, versus 8.5% for those who make more (or "high-income"). Further, the Sharpe ratio for those with lower returns was 50% higher (.49 versus .32).
"At the aggregate level, the risk-adjusted performances of IRA plans are comparable to that of the aggregate equity market," Lorenzo Bretscher of London Business School, Riccardo Sabbatucci of Stockholm School of Economics and Andrea Tamoni of Rutgers Business School write in their paper, "The Unintended Consequences of Roth IRAs."
"However," they write, "high-income individuals substantially outperform low-income ones, and this return differential is almost three times as large in 'tax-free' Roth IRAs, suggesting that their introduction, intended to help hard-working, middle-class Americans, greatly benefited high-income individuals and amplified wealth inequality."
ProPublica's investigation in 2021 of billionaire Peter Thiel's $5 billion Roth IRA highlighted the benefits of these accounts to certain investors, like Thiel, who use them to invest in early-stage startups that can later explode in value. As the study notes about that $5 billion, "no tax will ever be due on this amount."
The study's authors explored two questions: 1) What is the return performance of aggregate IRA plans, and Roth IRAs in particular, on average? and 2) Are the returns of high-income IRA investors economically different than those obtained by low-income individuals, at the aggregate level and across the different IRA plans?
They found the average return on aggregate Roth IRAs from 2004 to 2018 was 4%, "slightly lower than the 4.9% obtained by traditional IRAs," the authors state. Also, the Sharpe ratio of Roth IRAs was 0.287, lower than the 0.443 obtained by traditional IRA plans. They noted that the S&P 500 during that period returned 6.7% with a Sharpe ratio of 0.413.
Then they looked at performance among income groups. Those with income $10,000 to $100,000 earned an average of 2%-3% per year on their IRA investments, while higher income investors — those earning $1 million or more — had returns of 10% per year. Sharpe ratios were 0.351 and 0.519, respectively; therefore the risk-taking differential wasn't significant, the researchers found.
Likewise, those earning $200,000 or more outperformed the low-income individuals by a factor of three over the same period, the study found.
Inside IRAs
After breaking down income levels, the researchers looked at which IRAs accounted for the wide spread in performance between those making under $200,000 and those making over $200,000.
