Complex sentence: The economy improved during the latter half of the 1920s, and the bank reported increased profits, but then experienced the worldwide depression in the first half of the 1930s when annual net profits fell by more than half.
Split into simpler sentences: The economy improved during the latter half of the 1920s, and the bank reported increased profits. But then the bank was hit by the worldwide depression in the first half of the 1930s, and annual net profits fell by more than half.