David A. Moss, an economic and policy historian at the Harvard Business School, has spent years studying income inequality. While he has long believed that the growing disparity between the rich and poor was harmful to the people on the bottom, he says he hadn’t seen the risks to the world of finance, where many of the richest earn their great fortunes.
Now, as he studies the financial crisis of 2008, Mr. Moss says that even Wall Street may have something serious to fear from inequality — namely, another crisis.
The possible connection between economic inequality and financial crises came to Mr. Moss about a year ago, when he was at his research center in Cambridge, Mass. A colleague suggested that he overlay two different graphs — one plotting financial regulation and bank failures, and the other charting trends in income inequality.
Mr. Moss says he was surprised by what he saw. The timelines danced in sync with each other. Income disparities between rich and poor widened as government regulations eased and bank failures rose.
“I could hardly believe how tight the fit was — it was a stunning correlation,” he said. “And it began to raise the question of whether there are causal links between financial deregulation, economic inequality and instability in the financial sector. Are all of these things connected?”
Professor Moss is among a small group of economists, sociologists and legal scholars who are now trying to discover if income inequality contributes to financial crises. They have a new data point, of course, in the recent banking crisis, but there is only one parallel in the United States — the 1929 market crash.
Income disparities before that crisis and before the recent one were the greatest in approximately the last 100 years. In 1928, the top 10 percent of earners received 49.29 percent of total income. In 2007, the top 10 percent earned a strikingly similar percentage: 49.74 percent. In 1928, the top 1 percent received 23.94 percent of income. In 2007, those earners received 23.5 percent. Mr. Moss and his colleagues want to know if huge gaps in income create perverse incentives that put the financial system at risk. If so, their findings could become an argument for tax and social policies aimed at closing the income gap and for greater regulation of Wall Street.
This inquiry is one that some conservative economists are already dismissing.
R. Glenn Hubbard, for instance, who was the top economic advisor to former President George W. Bush, said income inequality was not the culprit in the most recent crisis.
“Cars go faster every year, and G.D.P. rises every year, but that doesn’t mean speed causes G.D.P.,” said Mr. Hubbard, dean of the Columbia Business School and co-author of the coming book “Seeds of Destruction: Why the Path to Economic Ruin Runs Through Washington, and How to Reclaim American Prosperity.”
Even scholars who support the inquiry say they aren’t sure that researchers will be able to prove the connection. Richard B. Freeman, an economist at Harvard, is comparing about 125 financial crises around the globe that occurred over the last 30 years. He said inequality soared before many of these crises. But, Mr. Freeman added, the data from different nations is difficult to compare. And Professor Freeman says he has found some places, like the Scandinavian countries, where there were crises without much inequality, suggesting that other factors, like deregulation, may be the best explanations.
For his part, Mr. Moss said that income inequality might have complicated links to financial crises. For instance, inequality, by putting too much power in the hands of Wall Street titans, enables them to promote policies that benefit them — like deregulation — that could put the system in jeopardy.
Inequality may also push people at the bottom of the ladder toward choices that put the financial system at risk, he said. And low-income homeowners could have better afforded their mortgages if not for the earnings gap.
(Mr. Hubbard has a different take: He says many lower-income homeowners should not have had mortgages in the first place. The latest crisis, he says, was caused by policymakers who decided to “democratize credit” by expanding home ownership. Their actions were driven by a desire to address inequality, but those policymakers were misguided and should have improved education instead, he adds.)
Scholars who study inequality often focus on people at the bottom. But, Mr. Moss said, the incentives of people at the top also deserve more scrutiny.
He pointed to the recent work of Margaret M. Blair, who teaches at Vanderbilt University Law School and is active with the Tobin Project, the nonprofit organization Mr. Moss founded a few years ago to study issues like economic inequality. She is researching whether financial workers promote bubbles and highly leveraged systems, even unconsciously. Ms. Blair said that because financial bubbles often lead to higher returns, financial workers have the potential to make more, and this pattern can influence their trading strategies and the policies they promote. Those decisions, in turn, drive even greater income inequality, she said.
After the 1929 crash, the income gap narrowed dramatically and remained low for decades, because of the huge wealth lost by people at the top and the sweeping financial reforms introduced in the 1930s that reined in Wall Street.
So far, the results are not as dramatic in the wake of the recent financial crisis. The income gap narrowed slightly in 2008, according to the most recent data available, but it remains unclear if it will continue shrinking.
This time, after all, the system did not collapse as it did in 1929. The status quo on income inequality looks like it was essentially maintained. Mr. Moss said he supported the government intervention in 2008, though he noted, "Financial elites made off rather well."
By Louise Story, Wall Street and Financial reporter for the New York Times.
A version of this article appeared in print on August 22, 2010, on page WK5 of the New York edition.