A widening gap between rich and poor is reshaping the U.S. economy, leaving it more vulnerable to recurring financial crises and less likely to generate enduring expansions. Left unchecked, the decades-long trend toward increasing inequality may ... shake social stability, economists and financial-industry executives say. Income inequality in this country is just getting worse and worse and worse," James Chanos, president and founder of New York-based Kynikos Associates Ltd., told Bloomberg Radio this week. "And that is not a recipe for stable economic growth when the rich are getting richer and everybody else is being left behind." Since 1980, about 5 percent of annual national income has shifted from the middle class to the nation's richest households. That means the wealthiest 5,934 households last year enjoyed an additional $650 billion -- about $109 million apiece -- beyond what they would have had if the economic pie had been divided as it was in 1980, according to Census Bureau data. Disputes over what constitutes economic fairness are moving to center stage amid a near-stagnant U.S. economy saddled with 9.1 percent unemployment yet boasting record corporate profits.