I was confused about this for the longest time. I thought why not just do a larger grant with a different vesting schedule. The supposed reason for the separation of New Hire RSUs and Sign-on RSUs is that it affects the mid point of the RSU grant for offers within a level and instead of making an out of band offer which increases the midpoint, they add on a Sign-on RSU which doesn't affect future salaries Very clever Snap, very clever