This excerpt taken from the THQI DEF 14A filed Jun 21, 2006.
Eligibility. All regular employees of the Company who work more than twenty hours per week and more than five months in any calendar year, and who have completed at least ninety (90) days of
continuous full-time employment with the Company on or before the first day of the applicable Offering Period will be eligible to participate in the ESPP. However, an employee will not be eligible to participate if, as a result of participating, that employee would hold five percent (5%) or more of the total combined voting power or value of all classes of stock of the Company or of any subsidiary. As of May 26, 2006, approximately 1,500 employees, including seven executive officers, would be eligible to participate in the ESPP.