Les trois essais, qui constituent les principales contributions théoriques et empiriques de cette thèse, sont présentés dans les chapitres1 à 3. Le chapitre 1 présente le premier essai intitulé « Relations politiques d'entreprise en Russie et leurs implications pour la performance et la rentabilité des entreprises ». Le chapitre 2 représente le deuxième essai intitulé « Banque et relations politiques en Russie et leurs implications pour les coûts au niveau de la dette ». Le chapitre 3 présente le troisième essai intitulé « Relations politiques d'entreprise en Russie et leurs implications pour l'activité d'acquisition au niveau de l'entreprise » Bien que développés séparément, ces chapitres sont interconnectés de façon cohérente, comme le montre la figure GI-1. Conceptuellement, la construction théorique principale dans ces trois chapitres est l'effet ultime que les liens politiques des entreprises ont sur la performance et la rentabilité des entreprises. Cet effet peut être étudié directement (pour obtenir une grande image de l'impact que ces différents types de liens politiques ont sur la rentabilité et la performance), et aussi indirectement (en examinant précisément les effets des différents types de liens politiques sur les déterminants de rentabilité et de performance). Plus précisément, le chapitre 1 aborde la grande image en régressant les ratios de rentabilité et de performance et de leurs déterminants fondamentaux sur différents types de relations politiques. Le chapitre 2 enquête précisément sur l'impact des différents types de relations politiques et bancaires sur le coût au niveau de la dette de l'entreprise, qui à son tour affecte la rentabilité et la performance, et le chapitre 3 examine les effets des différents types de liens politiques sur l'activité des acquisitions au niveau des entreprises qui potentiellement peuvent également affecter les ratios de rentabilité et de performance. Suite à ces trois chapitres, le mémoire se termine par une conclusion générale présentant les principales conclusions de cette thèse, les limites et les perspectives pour la recherche future. / This dissertation consists of three chapters representing three self-contained essays on the effects of corporate political connections on firm operational, financial, and investment activities. The research is based on a sample of Russian non-state-owned companies operating within the period of 2000-2013. Chapter 1 investigates the effect of corporate political connections on firm performance and profitability. I find that political connections to the executive branch of the central (federal) government positively affect connected firm’s return on sales, return on assets, return on equity and market-to-book ratio. These improvements are conditioned by better operating performance of the connected firm. At the same time financial and taxation costs are not seriously affected by political connections. Contrary to the effect of federal ties, connections to regional authorities bring more costs than benefits to the connected firms with both operating performance and overall performance indicators showing decline in presence of regional political ties. The latter effect can be explained by greater costs which regionally connected firms have to bear in order to contribute to the economic development of regions and provinces to which they are connected. Overall, Chapter 1 provides direct evidence on the effects of corporate political connections on firm profitability, performance, and their basic determinants, also showing that different types of connections differently affect performance. Chapter 2 examines the effect of corporate political and bank connections on firm-level cost of debt. I find that corporate connections to banks decrease cost of debt of a firm. However this effect works only if a firm has connections to a state-owned bank, not a private bank, and connections to a state-owned bank are to be maintained through a significant shareholder of the firm, not CEO, or board member. I also find that corporate connections to the executive branch of the central (federal) government decrease cost of debt. The latter effect works only if political connections are strong and cohesive enough, i.e. they were formed under circumstances that required high level of mutual trust and reliability between parties. Overall, the second chapter provides evidence that political and bank connections do really affect cost of debt and reveals important conditions under which connections can have an impact on this variable. Chapter 3 investigates the effect of corporate political connections on firm-level acquisitions activity. I find that political connections to central (federal) government positively affect firm’s propensity to purchase stakes in other firms. This effect works well in the domestic market, but not in the foreign markets. It does also work well with regard to acquisitions of stakes in the open market, but, ironically, not in the process of privatization. At the same time I find that political connections to regional governments are negatively associated with the probability of purchasing a stake by the acquirer. The latter effect may have an explanation that in a “small world” of regional political and business elites it is risky for participants to violate the regional equilibrium of wealth and power, thus firms demonstrate acquisitions activity levels lower than that of the reference group of unconnected firms. Overall, the third chapter provides evidence on the effects of corporate political connections on bidder’s acquisitions activity, showing, however, that different types of connections may differently impact bidder’s propensity to acquire stakes in other firms.