ESPP?!! Equity?!! At roughly $400/share, why is that important?!! The ship has sailed for making money on the stock. If you came in when the stock was in the $50s and they handed out a ton of equity on hire, fantastic. Now? Things are much different. Also, ESPP.......can you imagine having to give up roughly $400/per share, even with a discount how many shares will you be putting away? Trust me, I've been in this game before and at this point unless you are executive management where they hand you thousands of options, you're not going to make much on equity at Regeneron.
