Either (as the parent comment proposes) force them to pay dividends. Or don't: in order to profit from the higher share price, investors either have to sell some of their shares (realizing their capital gains) or use them as collateral for a loan (which should be treated as a capital gains realization event).
There are entire industries with thin margins (e.g. grocery, airline, blue collar services) that would be destroyed if you forced them to pay the same dividends as others.
Why are you fixating on share price? Now how are you going to tax LLC, LLP, etc.? Privately traded corps that don't have a market price?
As I said, forcing companies to pay dividends was the parent poster's idea. If anything like that were to be entertained, I'm sure the forced dividends would be in relation to the corporation's profit.
As for privately traded corps and partnerships: My proposal was to tax capital gains. This could be done at each realization event, and at that point your transaction will usually have a market price. If you are exchanging stock in two privately traded corps, some way to determine fair market value will have to be found, but that seems to be an edge case to me.
That would be double-taxing capital gains, since individuals are already taxed on it, and would de-incentivize companies from giving corporate income to workers while incentivizing companies to hoard economic wealth. You want companies to spend money, not keep it.
Most limited liability organizations also don't have equity, which creates another loophole in your system. Now you're starting to get into why corporate income tax is complex.
