Zynga has acquired 15 companies so far this year, including a few it hasn’t announced.

The information is included in an amendment to an S1 filing that the company filed today. The S1 is Zynga’s document for going public. The date for the IPO hasn’t been announced, but it is rumored to be expected after Thanksgiving.

For the nine months ended Sept. 30, Zynga acquired 13 game companies in the social and mobile game realms for a total of $40.6 million. Since Oct. 1, Zynga has acquired two more unnamed companies for another $4.9 million, bringing the total amount spent this year to $45.5 million.

That is quite a shopping spree, but it’s clear Zynga is still getting deals on its developer acquisitions, as the average purchase price is around $3 million. Zynga has more than 2,500 employees now, with many of them gained through acquisitions.

The deals include companies such as mobile gaming studio Astro Ape, acquired in August.