A aquisição por companhias abertas de ações de sua própria emissão no Brasil constitui o núcleo de estudo desta dissertação. Também referida como recompra de ações, trata-se de operação comumente realizada por sociedades anônimas, principalmente por companhias abertas, tendo em vista os possíveis benefícios na organização da estrutura de capital da companhia, conciliados com a variedade de motivações para sua utilização. O trabalho aborda, inicialmente, o tratamento legal conferido às operações realizadas por companhias abertas e fechadas, em especial pela Lei no 6.404, de 15 de dezembro de 1976. Além da definição das operações e sua evolução legislativa, são analisadas as principais causas que levam uma sociedade anônima a adquirir ações de sua própria emissão, assim como os negócios jurídicos passíveis de realização para que uma aquisição se concretize, além do aproveitamento a ser conferido pela companhia para as ações recompradas quando estas não forem canceladas, poderão ser mantidas em tesouraria na qualidade de bens de titularidade da companhia. O estudo também dedica-se à análise específica da aquisição de ações de emissão própria por companhias abertas, sob o foco do regramento expedido pela Comissão de Valores Mobiliários CVM. Além dos atos normativos emanados pela autarquia, a análise enfatiza os principais interesses a serem tutelados nas operações, assim como aborda precedentes da CVM sobre o tema. / The purchase, by publicly-held companies, of its own shares in Brazil constitutes the core area of study of this dissertation. Also referred to as stock repurchase, it consists in a transaction commonly performed by corporations, mainly the publicly traded, seeking out the benefits to the organization of the companys capital structure, combined with the variety of motivations for its use. This work initially discusses the legal treatment for stock repurchases performed by publicly-held and closely held companies, in particular by Law 6404, of December 15th, 1976. In addition to the definition of the transaction, and its legal developments, this study analyzes the main causes for a corporation to buy its own shares, as well as the legal act of the acquisition per se, and the use of the repurchased shares whenever they are not canceled, such shares will be held in treasury as assets owned by the company. The study also presents the repurchase made by publicly-held companies in view of the rules issued by the Comissão de Valores Mobiliários CVM (the Brazilian Securities and Exchange Commission). Apart from examining CVMs regulation, the study refers to a broad variety of cases decided by CVM on the subject, and investigates the main interests involved on the transactions.

Inscrite dans la dialectique changement-permanence, la stabilité juridique ne saurait s'opposer au changement normatif. Si rien ne changeait, il n'y aurait nul besoin de parler de stabilité, mais tout simplement d'intangibilité, d'immutabilité ou même d'éternité du droit. Par la stabilité, on cherche donc à garantir deux valeurs juridiques importantes : l'évolution du droit et la sécurité juridique. Tout produit juridique aspire à la stabilité. Sur le terrain du droit objectif, la stabilité est protégée afin d'éviter des situations d'inflation normative, de désordre dans la production normative, et de faciliter l'application des produits juridiques dans le temps. Sur le terrain des droits subjectifs, elle est souvent protégée afin d'assurer le maintien des situations juridiques individuelles malgré l'écoulement du temps. Ces aspects transparaissent dans le droit international des investissements à travers l'attente légitime de stabilité juridique. Cela étant, pour qu'une telle attente de stabilité juridique présente un caractère légitime, il faut qu'existe un engagement explicite ou implicite de l'État en ce sens et que les investisseurs se comportent d'une façon diligente et de bonne foi. Sur le plan substantiel, l’investisseur ne doit également pas s’attendre à ce que le droit ne change pas, car le droit est évolutif par nature. En revanche, il peut légitimement s’attendre à ce que les changements normatifs soient introduits de façon prévisible et non arbitraire. La violation de la stabilité juridique de la part de l'État engage sa responsabilité internationale. Au-delà de toutes ces considérations, la stabilité juridique fait face aujourd'hui à de nombreux bouleversements, le plus important semblant être son émergence en tant que principe coutumier de droit international. / Discussions of legal stability involve the notions of change and permanence; therefore, legal stability cannot oppose legal change. If nothing changed, there would be no need to talk of stability, and one would simply speak of intangibility, immutability or even of the eternity of the law. Through stability we seek to ensure two important legal values: the development of law and the principle of legal security. Stability is a central aspiration of every law. In the field of objective law, stability is protected in order to prevent a surfeit of laws, disorder in the legislative process and to facilitate the application of laws over time. In the field of subjective rights, it often exists in order to maintain certain specific legal situations and rights in spite of the passage of time. These aspects are reflected in international investment law through the legitimate expectation of legal stability. This being the case, so that such an expectation of legal stability be considered legitimate, there must be an explicit or implicit commitment by the State in this direction and investors must act diligently and in good faith. On the substantive side, it is also necessary that the investor does not expect the law not to change given that law evolves with time. Nevertheless, the investor can legitimately expect that regulatory changes be introduced in a predictable and non-arbitrary manner. Violation of legal stability by the State incurs international liability. Beyond these considerations, today legal stability faces a lot of challenges; the most important of which seems to be its emergence as a customary principle of international law.