This study presents the nonlinear relationship that exists between financial development and economic growth. This study applies the flexible nonlinear regression model of Hamilton (Econometrica 69(3):537–573, 2001) because it imposes no specification restrictions. Two empirical results are obtained. First, an inverted U-shaped relation between banking sector development and economic growth is identified. Namely, the two variables are positively linked before the turning point, but negatively linked after it. Second, a positive relationship with asymmetric √-shape between stock market development and economic growth is found.