Here's the calculation. Based on many assumptions (guesses) etc. Assumptions are blue. Result is red.
1. The IPO goes out at $18/sh and $4B valuation, implies 222.2M shares total.
2. IPO is rumored to be aiming at raising $650M, which would be 36.1M shares.
3. The DSP is set at 5% of shares, that would be 1.8M shares.
4. There will be 18,000 participants in the DSP, leaving 100 shares for each person on the average.
5. Note that they haven't said how these shares will be allocated among individual directors, employees, lenders, etc. I argue that I should get more than you, because ... well I'll think of something.
The valuation guess is probably close. The number of shares allocated to DSP is a cruder guess, and I think could be anywhere from 2% to 10%. The number of participants is anybody's guess. Fidelity is said to have said that 50,000 people signed up, but I doubt that a large fraction will follow thru.
If they were bold, and set the DSP at 10%, and then only 9,000 people participated, that would increase the result to 400 shares per person. On the other hand, if they set the DSP at 2.5%, and 36,000 people participate, then the result is 25 shares per person.