Swiss central bank steps up stock buying spree

By John Revill ZURICH (Reuters) - Switzerland's central bank now owns more publicly-traded shares in Facebook than Mark Zuckerberg, part of a mushrooming stock portfolio that is likely to grow yet further. The tech giant's founder and CEO has other ways to control his company: Zuckerberg holds most of his stake in a different class of stock. While most analysts think the strategy is sound, this does expose the SNB to stock market risks that the likes of the European Central Bank and U.S. Federal