But the stock price could have fallen. She should be credited with negotiating the deal and selling the company for 4.5B, and when she resigns the market cap isn't going to drop. She's not responsible for the market cap at all.
If you owned a share of the company, why would you sell to another investor for less than Verizon agreed to pay? Share prices rose 8.5% directly as a result of the price she negotiated with Verizon.