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Citing estimates that suggest income inequality in the United States is at its highest level in nearly 100 years, Janet Yellen said she was "greatly" concerned by "the most sustained rise in inequality since the 19th century."

"The extent of and continuing increase in inequality in the United States greatly concern me," Yellen said in a speech reported by the Los Angeles Times. "I think it is appropriate to ask if this trend is compatible with values rooted in our nation's history, among them the high value Americans have traditionally placed on equality of opportunity."

While Yellen lamented the country's current financial situation, the Federal Reserve chairwoman did not offer any concrete policy changes, either, the LA Times reports. Nor did she comment on criticisms that the Fed's maintaining low interest rates to stimulate the economy may actually be fueling income inequality; while the wealthiest Americans lost more initially in the Great Recession, those households have rebounded, whereas lower-income households have continued to struggle against low wages and a lack of employment opportunities.