Zynga (s ZNGA) has been trying its very best to diversify its business — with 93 percent of its sales coming from Facebook, it doesn’t have much of choice. Ben Schachter, Internet analyst with Macquarie Securities sent a note to his clients this morning after digging through the Facebook S-1. His take — it isn’t going to be a pretty fourth quarter of 2011 for the game-maker, who is still swimming in lukewarm waters since its public offering.

• The Bottom Line – The initial read-through for ZNGA is potentially a negative indication for ZNGA’s 4Q revenue estimate.
• Assuming ~93% of ZNGA’s bookings are generated through FB (average of first three quarters of 2011), then total net FB bookings for ZNGA for 2011 would be $1,117mm (based on FB’s ZNGA rev of $445mm divided by 30%, generating gross FB bookings of $1,484mm for ZNGA, then multipled by the 70% that ZNGA keeps).  This implies $268mm in total net bookings for the fourth quarter, while our model estimates $302mm in 4Q bookings.  In other words, unless ZNGA has meaningfully diversified its revenues away from FB, it could miss our 4Q bookings estimate.
• Additionally, this ignores the fact that some percentage of FB’s ZNGA revenue is generated by ZNGA’s purchase of FB advertising, thus the actual ZNGA bookings from FB is likely even lower.
• Where we could be wrong – there could be other definitional items around revenue recognition and advertising that we are failing to incorporate into these estimates.