What does the "discount" mean in the last sentence?

Just the same after a long bear market or a long wave of depression, business people become pessimistic and under-estimate the public requirements or consumption. This causes prices to rise because production has fallen below consumption. Competition always gets keener near the top when more is being produced that can be sold, and the result is a decline in prices whether it be commodities or manufactured articles. The stock market discounts these changes in advance.