Wall Street seems to have learned a neat trick: how to make more money while producing less.

Between 1980 and 2010, the U.S. financial industry nearly doubled in size, relative to the overall economy. Yet in terms of what the financial industry actually produces -- liquidity, assets, anything of measurable benefit to society -- the sector appears to be doing less these days than it used to.

That, at least, is the contention of Thomas Philippon, an associate professor of finance at the New York University Stern School of Business whose 2011 paper -- "Has the U.S. Finance Industry Become Less Efficient?" -- is circulating the blogs this week.

Philippon's conclusion -- based on an analysis of the financial sector's output in recent decades, as well as what its workers have been collecting in profits and wages -- is that high finance is highly inefficient. For what the industry produces, it should be significantly smaller than it is, according to Philippon.

As it is, he writes, the financial sector is taking in money in a way that doesn't make sense: "[A]bout 2% of GDP, or about $280 billions annually, are either wasted or at least difficult to account for."

Philippon's paper echoes an assertion often heard from members of the Occupy movement, and that was seen chalked on the sidewalk at Zuccotti Park last fall -- the idea that "banks create nothing."

Philippon is hardly the first to ask why financial-service workers are paid so highly, and why that industry's share of the total economy has skyrocketed in the space of a generation. And he reaches an often-heard conclusion: New technologies have enabled traders to make lots of fees.

This isn't what social historians consider to be the main function of banks. Rather, the financial services industry emerged as a way to help money move between people, businesses and governments. But between the rise of computer-assisted trading and the gradual retreat from federal regulation that was a hallmark of presidential administrations from Reagan through Bush II, the Wall Street of the late 20th and early 21st century lost focus.

Following the financial crisis of 2008 -- largely the result of major financial institutions making unregulated trades with poor-quality assets, in the hopes of generating ever larger profits -- President Obama vowed to make financial regulation a top priority.

It's unclear how much has changed, with the vast majority of rules in the Dodd-Frank reform package still unwritten, and with Wall Street firms taking in greater profits during Obama's first three years in office than they did during the eight-year administration of George W. Bush.