The S&P 500 ended the day down 1.5 percent, and the yield on the policy sensitive two-year treasury had its highest level in 16 years. The implication here is that the central bank could opt for a 50 basis point rate rise when it meets in two weeks. But some economists say it depends chiefly on the outcome of incoming data before the next meeting. And if let's say those numbers come in stronger than expected or do not show a significant kind of deceleration from the pace of the previous month, then the Fed may follow through with this more aggressive outcome.