The diffusion of R is certainly an interesting phenomenon on many counts. First, it encompasses many different fields of academic as well as applied research. Second, it’s been developing as one of the dominating analytics tools in areas such as mining of big data sets and finance, for example. Third, it has tickled a large, active, and enthusiastic global community that has been adding useful and interesting functionalities (called packages) to the primary packages provided by the core development team of R-Project. Fourth, it is open source software with all its obvious benefits (and drawbacks, as well) that it implies.
What is R? It is an environment for statistical computing and graphics ranging, listing only some of its major capabilities, from linear and non-linear modelling to time series analysis and clustering — where, by stressing environment is meant it is a comprehensively designed and coherent system as opposed to specific and disconnected functionalities packed together in a single software.
The financial community has embraced it both at the academic and at the business levels relying on its highly integrated facilities for data manipulation, computation and graphical capacity. Computational finance and risk management are the first areas where its clear-cut, flexible and scalable functionalities yield the most appreciated results, though investment banking, trading and asset management have all drawn extensively on R and its extending packages — uncountable are the collections of financial and econometric packages designed for performance analysis (the PerformanceAnalytics package is one of the most well known).
Though Excel runs Wall Street to a good extent, the advent of quantitative finance in the early nineties has marked the entry of other more sophisticated computer coding and charting tools. Uncountable are the initiatives under which falls R with its extensive libraries (again packages): it is easy to check the size of its financial extensions by looking at CRAN comprehensive catalog on finance.