Investors in Europe sighed and then got back to business after a crucial Greek vote Sunday. Markets showed an early advance Monday, but soon receded as Spanish bond yields topped 7 percent and anxiety over the future of the euro zone continued unabated. “Any relief following the Greek election results should be brief,” Ciaran O’Hagan, Société Générale SA’s head of interest-rate strategy, told reporters. “At best, we are facing a muddle-through scenario in Greece. The focus now returns to Spain, where the latest developments continue to trouble us.” Spain presents the latest front in the fight for the 17-nation common currency and recently became the fourth nation to ask for a bank bailout. American stock futures slid Monday morning as Spain's economic troubles continued to become more apparent, and investors placed a vote of little confidence in the country's ability to pay off its debt.