Most (all?) public tech companies have policies that prohibit employees from trading the company's stock outside designated windows following a quarterly earnings release.

Earnings reports happen once a quarter between the company and the public. A couple of business days after that, employees (without material nonpublic info) may trade company shares for the next month or so. Maybe you can't sell April shares until mid-July, and then you have to decide whether to wait until next July to minimize tax on gain.

Sometimes you can elect to sell every released share in a quarter, or file a 10b5-1 plan with a schedule, but you have to do that during a trading window.