The present value of the securities is certainly one aspect of measuring the value of said securities to Mr. Zuckerberg. Another aspect would also be the contro

The present value of the securities is certainly one aspect of measuring the value of said securities to Mr. Zuckerberg. Another aspect would also be the control of his company that he's giving up (since it's primarily stock I assume). The second one I believe is one that would interest Mr. Zuckerberg more than the dollar value of said securities. But even then, it probably amounts to a negligible steak in the company as well.