The foreign currency market is the largest and deepest market around by a long shot. If you have a few billion dollars to place, bringing them to the stock market is going to move the stock's value and tip off other traders as to what you are doing. So if you have a substantial amount of money to move around, this is the place to do it. You can get in and out without affecting the market. The foreign currency market is the place to do it.
Banks are no longer the big players in terms of supplying credit.
For example, if a German chemical company invests in a plant in India, it makes the investment in deutsch-marks. The chemical products sold locally from that plant are paid in rupees, India's currency. If the value of the rupee then drops in terms of the deutschmark, the return on the original investment will drop as well. Corporations have followed two major strategies to deal with this risk. The first strategy is the reorganisation of the corporate conglomerate.