Credit Suisse announced it will combine support operations for its investment and private banking divisions - part of its efforts to reduce annual costs by $2.1 billion by 2013.  The broad move, which begins in 2012, will result in the elimination of 3,500 jobs worldwide. Informed sources report that:  (i) back-office functions, including trade settlement, will be brought together;  (ii) about 50% all planned layoffs will come from the investment banking unit - with Gary Bullock leading the new combined operation. The Swiss financial institutions, in particular, have aggressively sought ways to cut costs and bolster earnings.  Last month, for example, Credit Suisse announced it was combining the operations of an independent subsidiary, Clariden Leu, with its other private banking units  - a step that will eliminate overhead costs.  [Dealbook 12/15/11]