The financial sector was ten times the size of the real sector when global financial crisis ocurred. this means that it was just an illustion. When GNP is measured both sectors are added together. It would lead to interesting results if we separated the two sectors. Some relevant material is
Atiyab Sultan's MPhil Thesis showing the negative effects of financial growth on real growth.
The financial sector and the real economy
Dietmar Peetz and Heribert Genreith, Downloadable from Real World Economic Review, Issue 57