European stocks ended the week on a downbeat note, burdened by renewed escalations of tensions in Ukraine, erasing gains made earlier in the week.

Russian assets failed to recover after ratings firm Standard & Poor's slashed the country's credit rating by one notch to the brink of junk, driving stocks and the ruble lower and government yields higher. Also on Friday, the country announced a surprise interest-rate hike, citing a heightened risk of inflation.

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