Wider parts of society-at-large are not fluent in the language of numbers, and financial literacy in particular is low in many countries (OECD, 2014). This paper shows how research on financial communication with and for practitioners (Cameron, Frazer, Rampton, & Richardson, 1992, p. 22) can foster intra-lingual translation in the financial sector, which increases financial texts' communicative potential and finally enables laypersons to better understand the language of numbers. Transdisciplinary Action Research (TDA) offers a framework and procedures to approach such goals through close collaboration of scholars and practitioners throughout research projects. Following TDA core concepts, a cyclic process of research and development has been established in the last two decades (e.g. Perrin, this volume; Whitehouse, 2014). Whereas applied linguists involved aimed at better understanding practices of writing and intra-lingual translation at the interface of technical and everyday language, stakeholders from the financial industry wanted to improve their communication. The representatives of society-at-large, finally, were interested in contributing to sustainably increasing financial literacy. In the first part of the present paper, I sketch the suitability of transdisciplinarity in general and TDA in particular in financial communication (Section 1). Then I define the key concepts of intra-lingual translation, communicative potential, and financial literacy (Section 2). Next, I outline the data corpus and explain how TDA was applied in a series of research projects (Section 3). The presented results on a macro-level shed light on the financial analysts' situation and practices in their multilingual workplace: the findings on the micro-level suggest that financial analysts' texts pose a risk of partial communicative failure (Section 4). The article concludes by indicating empirically based measures to develop financial literacy, intra-lingual translation across stakeholders and texts' communicative potential in finance (Section 5).