Janet Yellen won't say when interest rates will rise because she doesn't know

Markets might want more clarity on exactly when interest rates will go up, but they're not likely to get it from Fed Chair Janet Yellen. In a closely watched speech on Friday, Yellen provided a more detailed view of her economic outlook but at the same time raised new questions about what the Fed will do next. The Wall Street Journal's Pedro da Costa summed up her stance on interest rates perfectly: