The index of business activity in Germany declined in September to 103.7 points from 103.9 points in August, data of the IFO showed. Analysts had expected the decline to 103.2 points. The indicator, which determines the business expectations of German companies, dropped to 101 points from 101.3 points in the previous month, mainly due to the weakening of the indicator in the manufacturing industry. Improved sentiment was observed in the retail and service sectors. The construction sector also showed growth in business activity. IFO data indicated a decrease in the index of current business conditions in September to 106.4 points from 106.5 points.