[en] This doctoral thesis presents the results obtained in the study on the demographic characteristics and economic and financial behaviour of Spanish high-growth companies. Previously the literature has focused on the investigation of the effect of different factors on the growth process of companies, but not enough evidence has been found to analyse the effect of economic and financial variables. Thus, this research studied, first, the demographic characteristics that describe high-growth companies and, second, the economic and financial variables that characterise this type of company, comparing it with another sample of companies not considered high-growth. Finally, it explored the effect of a series of economic and financial variables on the level of indebtedness of this typology of companies. To achieve the purposes of this doctoral thesis, three different empirical studies were carried out. The results obtained in the first exploratory study show that, although high-growth companies have a heterogeneous profile, the majority are small in size, newly-formed, operating in the service sector, and not persistent over time. On the other hand, the results of the second study reveal that there are economic and financial variables that characterise high-growth companies and that the ones that best differentiate them from those not considered high-growth are "growth in assets", "growth in debt", and ROE and ROA profitability variables. Therefore, these conclusions have led to a third study with the aim of analysing the factors that determine the composition of the financial structure of the companies. The results obtained confirm that there are differences in the financing policy of high-growth companies compared to companies not considered high-growth.

[eu] Tesi honek espainiar hazkunde azkarreko enpresen ezaugarri demografiko eta jokaera ekonomiko-finantzarioaren inguruko ikerketaren emaitzak aurkezten ditu. Aurretik literatura enpresen hazkunde prozesuan eragiten duten faktore desberdinen ikerketara bideratu da, baina ez da aurkitu aldagai ekonomiko-finantzarioek daukaten eraginari buruzko ebidentzia nahikoa. Horregatik, ikerketa honetan, lehenik eta behin, hazkunde azkarreko enpresen ezaugarri demografikoak aztertu nahi dira, bestalde, enpresek ezaugarritzat dituzten aldagai ekonomiko-finantzarioak aztertzea, hazkunde azkarrekoak ez diren enpresekin konparatuz. Azkenik, enpresa hauen zorpetze mailan eragiten duten aldagai ekonomiko-finantziarioak ere aztertu dira. Helburu hauek aurrera eramateko, hiru azterketa enpiriko desberdin egin dira. Lehenengo azterketaren emaitzei dagokionez, hazkunde azkarreko enpresek profil heterogeneo bat dutela ikusten den arren, gehienak tamaina txikikoak, gazteak, zerbitzu sektorekoak eta denboran zehar ez iraunkortasunik gabekoak dira. Bestalde, bigarren azterketaren emaitzei dagokionez, analisi diskriminatzaile bat egin da non aldagai ekonomiko-finantzario batzuk hazkunde azkarreko enpresen ezaugarri direla adierazten den, aktiboen hazkuntza, zorpetze mailaren hazkuntza eta errentagarritasuna, hain zuzen ere. Horregatik, emaitza hauek ikusita, beste hirugarren azterketa bat egitea aproposa dela iruditu zaigu enpresen zorpetze-mailan eragiten duten faktore desberdinak zeintzuk diren jakiteko. Zentzu horretan, hirugarren azterketako emaitzei dagokionez, hazkunde azkarreko enpresa eta hazkunde azkarrekoak ez diren enpresen artean aurrera eramaten duten politika finantzarioan desberdintasunak somatu direla baieztatzen da.