They're talking about the amount of time you have after leaving a company to exercise the stock options that you were granted, effectively purchasing them at pa

They're talking about the amount of time you have after leaving a company to exercise the stock options that you were granted, effectively purchasing them at par value. This has huge tax implications, and requires quite a bit of cash on the spot. Traditionally, the period has been ~90 days, which makes it even harder to weigh your tax options and come up with the $$$$ to exercise the options. Since its expensive, and has a short window of execution, the practice has been viewed by many to be unfair. The Stock Options were a part of your compensation - part of the Risk vs Reward balance you choose when you worked for a startup, and now if you don't have thousands of dollars to spare on a gamble - you forfit those options back to the Company. By extending the period to 10 years, you have the ability plan accordingly, see if the company will eventually exit, and exercise them when the time is right.