LONDON (MarketWatch) -- Greek bonds and stocks slumped on Friday afternoon after the country's finance minister Yanis Varoufakis told reporters that the new government won't cooperate with the troika of international lenders. The yield on 10-year Greek government bonds jumped 80 basis points to 11.054%, while the Athex Composite stock index gave up 1.6% to 721.93. Speaking alongside Eurogroup ...