Stock bonuses are taxed as ordinary income. Stock options are a little more complicated due to vesting but are typically taxed as ordinary income when exercised and a capital gain when sold. I’ll ask again….why are we wanting to treat increases in stock prices as a taxable event? Are we talking only about options?
The stock they acquire early on in the life of the company they built is almost never exercised. The gains are never realized nor taxed, though they keep using them to borrow against as the company's value rises, and then upon their death, they play tax tricks with trusts to dodge estate taxes.
Let's look at Zuckerberg. His compensation at facebook is $1 salary. 0 in stock options. 0 in stock. 0 in bonus and ~23 million in other types of compensation (likely the use of cars, planes, etc...).
But he owns 29.3% of the entire company compared to 28% at IPO. The growth of the company is financing his ability to increase his wealth via these security backed loans which allow him to bypass needing to sell even a small percentage of his facebook stocks to fund his lifestyle or his investments in other assets and also allow him to not need to take a salary. So he bypasses the tax on his salary. He bypasses the stocks on his capital gains and he uses the interest deduction from his securities loans to decrease his overall tax burden resulting from his "other" compensations. He just has to sell enough of his other (non-facebook) assets to look like a net loss (or a comparably infinitesimal gain) considering his interest payments. It ends up looking like he's making nothing, when in reality our tax code is allowing him to not need to show much if any "income" despite living like he does have income. You might think that in some way his revenue growth was being taxed in the form of corporate taxes, but we know the tech giants do as much as they can to pay 0 in corporate taxes too.
Instead of taxing the profits prior to them being realized, I suppose we could always outlaw securities based personal lending... but then these guys would just try to do it through shell corps and other tax strategies. Seems like the most effective way would be to figure out how to tax stock gains when the person holding the stock has over an xyz% stake in the company.
I only see a few avenues of fixing this and some of them would mean waiting decades to recoup the lost tax revenue.
A) figure out how to tax the stock gains, at least at some rate that mainly effects massive stock holders, and do so without killing legitimate corporate investment firms and tanking the economy.
B) figure out how to effectively close off securities based loans (both private and corporate) which are ultimately benefitting single individuals
C) fix the estate tax system (including limiting trusts) to insure that assets are appropriately taxed upon death and that the assets don't reach heirs without appropriate redistribution.