An Economist article last year estimated that institutions run by the Catholic Church—mostly hospitals and educational institutions—spent $170 billion in the United States alone back in 2010.
For comparison's sake, Apple had $157 billion in revenue in Fiscal Year 2012. In fact, just 16 companies had more than $170 billion in revenue. But that's global revenue and obviously the Catholic Church has extensive operations in Europe and Latin America alongside its United States branch and smaller Asian and African outlets. One interesting issue is that, legally speaking, there is no Catholic Church. In the United States, each diocese is a separately incorporated entity with no formal linkages between the different diocese or the Vatican. The underlying spirital organization is different, but not reflected in the legal org chart. And religious institutions aren't subject to normal nonprofit accounting or reporting rule, so really understanding the underlying financial structure is difficult.