The S&P 500 dropped as much as 0.5% on the news after trading little changed for most of the morning. The Dow slipped 0.4% as of 11:34 a.m. ET, while the more tech-heavy Nasdaq Composite lost just 0.1%.
In currency markets, the Russian ruble slid as much as 1.3% versus the US dollar.
This story is breaking check back for updates.