Shares of the Market Vectors Russia ETF (NYSEArca: RSX) are off 3% in midday trading after Standard & Poor’s placed Russia’s sovereign debt on CreditWatch with negative implications, indicating Russia could lost its already tenuous grasp on its investment-grade credit rating.

In April, Standard & Poor’s lowered its rating on Russian sovereign debt to BBB-, the lowest investment grade. It was the first time the ratings agency has downgraded Russia since 2008. Russia’s BBB- rating is the same as fellow BRIC members Brazil and India, but it looks like Russia is the most vulnerable to being lowered to junk status. [Russia ETFs Slide After S&P Downgrade]

S&P’s move to put Russia on CreditWatch negative reflects the ratings agency’s “view that there is at least a one-in-two likelihood of a negative rating action within 90 days,” according to S&P.

“The CreditWatch placement stems from what we view as a rapid deterioration of Russia’s monetary flexibility and the impact of the weakening economy on its financial system,” said S&P.

In late July, S&P Dow Jones Indices, one of the largest providers of indices for use by exchange traded funds, consulted with clients regarding the inclusion of Russian securities in S&P indices in the wake of broadening economic sanctions against Russia.

In August, S&P announced it would ot remove Russian stocks from the firm’s various benchmarks following the aforementioned consultation. [S&P Keeps Russian Stocks in its Indices]