Also, the money isn't really all gone to a 3rd party, it's in a foundation-type entity similar to how Zuck does it.
The foundation-type entity is correct though, she will still be overseeing how it's spent.
See: http://www.fidelitycharitable.org/giving-strategies/tax-esta...
EDIT: Perhaps you're saying she donated her shares to the Donor Advised Fund first, and then the Fund sold the shares to Google? Possible I guess, but that's not what the SEC notice said.
https://www.sec.gov/Archives/edgar/data/1652044/000090342316...
"Diane Greene exchanged 7,244,150 shares of bebop stock for 200,729 shares of Alphabet Class C Capital Stock at $740.39 each in the Merger, plus cash for fractional shares. Ms. Greene intends to donate the shares exchanged to a donor advised fund."
You have to structure the deals this way, otherwise you lose more than half of your company to the government. When marginal rates exceed 50% and you have dependable future earning potential, yes, giving away unrealized gains can be worth more than realizing them.
By donating $150m to the Fund, you not only get the self-directed Fund with $150m dollars in it (which is a fun time in and of itself) but you also get $150m in charitable deductions. Each dollar of that deduction eliminates > 50 cents on the dollar of tax liability. Donating to the Fund effectively lets you have your cake and eat it too, again, with the caveat that you expect to have enough future income to use it all up, while remaining in the highest tax bracket.
You can "carryover" deductions from charitable contributions that you are not able to use up in the current year for up to 5-15 years.
https://www.taxslayer.com/support/530/charitable-contributio...