PARIS — Market enthusiasm over the Spanish bank bailout did not last even a day.

After a strong day in trading seemed to roll on to Europe on Monday morning, by afternoon most European indexes were flat. And investors were selling Spanish and Italian stocks and bonds amid skepticism that the euro zone was any closer to solving its underlying problems.

And the specter of a Greek exit from the euro zone, depending on how elections turn out next weekend, could loom over trading throughout the week.

“There are chronic problems and there are acute problems,” said Kenneth Wattret, chief euro zone economist in London for BNP Paribas. The deal reached for Spain over the weekend “has dealt with one of the acute problems.”

The chronic issues, including fiscal imbalances and deteriorating economies in the euro zone, remain to be addressed, he said, although he pointed to a growing sense of urgency among European Union officials as at least one reason for optimism.