This has been discussed here in a previous thread. Inflation can help the earnings of some companies. BUT, the problem is that even if inflation helps earnings, the discount rate applied to those earnings increases as well, thereby reducing the present value of said earnings (i.e., the stock price). The negative effect of inflation on the discount rate (and thus stocks’ present value) is typically much greater than any positive effect on earnings. So, for the most part, inflation is bad for stock prices. See the 70s for a good example of this.
