In these turbulent times, stock markets need a calming influence. I propose a stock market where one can trade in things that are guaranteed to stay the same, eg pi, the speed of light in vacuum, the number 16 and so forth.

The level graphs, constant figures and reassuring statements in the financial
press ("and pi is continuing a 14 billion year period at a rate of 3.14....") would help to reassure investors in other markets that do not have the backing of the whole universe.