Details of the Chinese interest rate cut

Yellen's appearance last week was notable for how little she said but one thing stood out: China. She singled out international economies as a risk to the US outlook but instead of focusing on Europe, Japan or commodity producers, the first country she mentioned was China.

The surprise interest rate cut from the People's Bank of China on Saturday may show that concerns are real.

Bloomberg breaks down the move.

"A rate cut was urgently needed," said Wang Tao, the chief China economist at UBS. "The debt burden is heavy, and the PBOC has to act to keep the financial market stable."

Economists are already clamoring for more cuts.

"This time the PBOC acted very well," said Shen Jianguang, the chief Asia economist at Mizuho Securities. "After two rate cuts, the financing costs will be cut down pretty effectively, but more rate reductions are still needed."