While financial intermediation provides a multitude of benefits to investors and promotes economic growth, its players can experience large outflows of funds in tight market conditions and their actions can contribute to the transmission of crises among financial sustem actors. After the 2008 crisis, it became clear that a better understanding of their functioning and the risks inherent to their activities is crucial to improve regulation of the sector. With this PhD thesis, we attempt to study how the activities of investment funds can impact financial stability.