Box IPOed at $14/share but spiked to $23/share on the first day of trading. Assuming 50K shares (and ignoring the strike price / any upfront cost he might have paid), total additional compensation was ~$700K to $1.150M.
You can make a pretty good guess at strike price from Box's financing history. They raised a Series F in 2013 at $2B post. There are currently 141M shares outstanding, of which 12.5M were offered in the IPO and roughly 10% of the company (13M) shares was sold in the Series F & Series G, so figure 120M shares outstanding at the time of his option grant. That implies a strike price between about $10 (@ the $1.225 Jul 2012 Series E valuation) and $17 (@ the Dec 2013 Series F valuation).
At the end of the 6-month lockup Box's shares were worth $17, so that would imply his options were anywhere from +$175K (he'd only have vested half of them, with standard 4-year grants) to just slightly underwater. If he held to the $28 peak this May, he'd be anywhere from +$500K -> +$900K, but if he kept holding them, he could potentially be underwater today. It's a nice additional bonus (particularly if he got in at the Series E valuation), but not enough to make one rich.
first day of trading makes no difference whatsoever. Employees are usually locked in for about 6 months, by which point the stock will have probably crashed to below IPO levels
