Wall Street saw one of its most brutal selling sessions overnight in over a month as rising deficit worries led to a spike in bond yields, which in turn hit sentiment around equities. The run-up seen from lower levels also was a big factor in investors choosing to take money off the table as uncertainties rose.

Stock futures declined before the opening bell Monday after the U.S. credit rating was downgraded by Moody's Ratings on Friday. As of 8:30 a.m. EST, S&P 500 futures had shed 65 points, or 1.1%, while Dow Jones Industrial Average futures declined 252 points or 0.

Dow slides as Treasury yields surge above key levels. Traders eye deficit risks, stalled tax bill, and Fed signals for the next stock market move.