Given a certain dollar amount (e.g. X% of salary), the number of RSUs to grant is calculated by dividing the dollar amount by the market price of the stock. There are two common ways to calculate the market price of the stock, and the difference comes down to this:
1. The market price of the stock is determined at the time of the grant, and;
2. The market price of the stock is determined at the time the RSUs vest.
If there’s a one-time grant that is given immediately, the two values are usually going to be very close. But if the grant vests over some number of years (e.g. four year schedule, 25% vests after one year, remaining 75% vests monthly), the difference between the two methods can differ greatly.
When the price is determined at grant time, employees benefit from the stock rising, and are penalized if the stock falls. When the price is determined at vesting time, employees end up with the same compensation no matter what the stock does, they only benefit from appreciation if they hold the stock and it appreciates after vesting.
In your company, do the bonus RSUs have a vesting schedule? Or are they granted and distributed shortly thereafter?