[pt] Os modelos de Black & Scholes e binomial para avaliação de opções financeiras dão como resultado prêmios cujo valor aumenta proporcionalmente ao aumento da incerteza do retorno dos ativos subjacentes às opções, medida pelo desvio-padrão. Também na avaliação de empresas, a teoria das opções financeiras pode ser estendida para avaliar as mesmas como opções reais. Este método é adequado quando se analisam ativos de empresas sujeitos a fortes incertezas, situação na qual a flexibilidade das opções adiciona valor considerável aos ativos físicos. Seguindo esta ótica, a pesquisa analisou uma linha aérea internacional de uma empresa de transporte aéreo regular de passageiros. A análise é adequada na medida em que a indústria do transporte aéreo, atualmente em crise, está sujeita a fortes incertezas de receita de passageiros e também de custos como o de combustível. Pela análise por opções reais, a pesquisa demonstrou que a flexibilidade existente acerca das opções de aumentar, reduzir freqüências nos vôos ou até mesmo abandonar as operações, aliada às incertezas de mercado, adiciona valor considerável aos ativos de uma empresa aérea. Assim, avaliar as mesmas apenas baseando-se no método ortodoxo do Valor Presente Líquido num cenário de crise como o atual, constitui-se numa análise incompleta. A pesquisa utilizou uma modelagem discreta no tempo e estado, com a combinação das incertezas de receita e combustível evoluindo segundo uma árvore quadrinomial. / [en] The Black & Scholes and the binomial models for financial options valuation give, as a result, premiums whose value increases proportionally to the increase of the degree of uncertainty about the return of the underlying assets, as measured by the standard deviation. When companies are valuated, financial options theory can be extended to valuate them as real options. This method is adequate when analysing company assets subjected to great uncertainty, in which the options flexibility adds considerable value to the physical assets. In this context, this research shows the analysis of an international airline of a regular passenger air transport company. The analysis is adequate as long as the air transport industry, nowadays in crisis, is subjected to strong uncertainties like passenger revenue and fuel costs. Through the real options analysis, the research showed that the flexibility given by the options of increasing or decreasing flights frequencies, and even of abandoning operations, together with the Market uncertainties, adds considerable value to the assets of an air carrier. In this sense, valuating them only according to the orthodox method of the Net Present Value in a scenario of crisis as nowadays, is an incomplete analysis. The study was based on a discrete time and discrete state model, combining the evolution of revenue and fuel cost uncertainties according to a quadrinomial decision tree.

Cette thèse examine les décisions financières à travers la théorie des options Américaines et Exotiques. Dans un premier temps, nous avons présenté une revue de la littérature sur les options de type Américain. La tarification de l’option Américaine standard d’achat est revisitée en vue de fournir les pré-requis. Dans l’étape suivante, un nouveau type de contrat d’option, appelé Strangle Euro-American ou Strangle Hybride, a été introduit. Des formules analytiques ont été fournies pour leurs prix ainsi que leurs paramètres de gestion. Une nouvelle méthode est proposée pour calculer les intégrales qui définissent les bornes d’exercice anticipé. Il a été démontré que cette méthode est efficiente, précise et rapide pour la tarification de tous les types de Strangle voir au delà. Puis, nous avons examiné les options Step de type Américain. Nous avons démontré que les propriétés des options d’achat "vanille" ne s’appliquent pas aux Step dans certaines situations. Les formules d’évaluation et des paramètres de gestion ont été déterminés. Et enfin, nous avons considéré l’évaluation d’une firme détenant simultanément une option d’abandon et une option d’expansion de ses activités selon des conditions du marché (favorables ou défavorables). Les seuils critiques de décision ont été obtenus. Des formules analytiques pour la valeur de la firme ont été obtenues. Des simulations illustrent le comportement de ces seuils critiques de décisions anticipées. / This thesis investigates the financial decisions through the theory of American and Exotic options. First, the literature on American-style derivatives is surveyed. The pricing of standard American call option in the early exercise premium representation is addressed in order to provide prerequisites for what follows. Second, a new variant of Strangle contracts, called Euro-American or Hybrid Strangles, is introduced and priced. Analytical formulas are provided for the prices of all these option contracts as well as their hedging parameters. A new quadrature is proposed to account for the systems of coupled integral equations that locate the early exercise boundaries. It is shown to be efficient, accurate, and fast for pricing all types of early exercisable strangles and more. Third, we examines the valuation of American Step options contract. The structures of the immediate exercise regions of the various contracts are identified. Typical properties of American vanilla calls are shown to fail in some cases. Formulas for prices and hedging parameters, for the American Step options, are derived. Finally, we consider the valuation of a firm holding simultaneously an option to expand and to abandon productions depending on the state of the market (good or bad) in a real option framework. Optimal decision levels are obtained. Analytical formulas for the firm’s value are provided. Numerical results document the behavior of the firm’s value and optimal exercise boundaries levels.