Define &quot;keep.&quot; This much money does him no good sitting in a bank account. I&#x27;m sure he intends to invest it. One option would be to cash out, take a huge tax hit (in CA) and then reinvest. That is pretty foolish if you have this kind of money. The better option is to form a company. Even better, form a non-profit. Sign over the stock to the non profit. The non-profit then re-invests the money. Make yourself an employee. Set your own salary and make yourself the CEO. Now he has reinvested the money and hasn&#x27;t taken any tax hit EXCEPT on his income (which would have been taxed regardless of what he did). The other billions he has are sitting there earning interest tax free until he decides to take some out.<p>On that taking some out bit... So, as the CEO of this non-profit, he could have the company buy a jet, build an office, schedule company retreats, etc... All of this would be tax free.<p>I could go on, but I think that the point is clear. Non-profits are an EXCELLENT way to avoid tax hits in this sort of scenario. It&#x27;s a numbers game. Once your net worth has a B at the end of it, forming an entirely new business just to avoid taxes becomes a much more sensible solution.