Zynga’s profits fell by 90% for its June quarter this year thanks to a mix of spending and a lack of major game releases, according to a regulatory filing reviewed by Reuters.

The filing reveals that the company’s total costs and expenses increased by $149 million compared to the same quarter of last year, and rose by $59 million compared to the previous quarter. Revenue for the quarter ending June 30, however, rose to $279 million for a 115% increase over the previous year year.

Reuters speculates that the June 1 launch of Empires & Allies on Facebook might explain the dip in profits. We observe, however, that Zynga had a similar summer release schedule for 2010 where FrontierVille didn’t launch until even later in the month of June. Zynga did, however, spend more money on acquisitions in 2011, picking up talent from Wonderland Software in April and purchasing Casino City developer DNA Games in May.

Zynga reduced the probability that it will IPO by five percentage points in a valuation exercise in August. It put the probability of an IPO at 75 percent, down from 80 percent three months earlier amid global market turmoil. Zynga said a third-party valuation in August found that its outstanding equity was worth $14.05 billion, up from $13.98 billion in May despite the global equities rout.