German confidence in the economy sank back this month, buffeted by disillusion over the European Union’s trade deal with the U.S. and Germany’s weaker-than-expected economic performance in the second quarter.

The ZEW Indicator of Economic Sentiment, which this month tracked the expectations of 182 analysts at banks, insurance companies and other businesses, dived 18.0 points on month to 34.7 in August. Economists polled by The Wall Street Journal expected a slightly stronger score of 38.0.