Each annual Call of Duty title is the collective effort of multiple studios working together for years. In a 2021 investor report, Activision stated there are over 3,000 workers assigned to the franchise. With production values that high, Sony maintained that no other publisher could possibly challenge Activision's position in the market, citing Electronic Arts' Battlefield (another blockbuster military action series) as a competitor that has still fallen woefully short of threatening the world's most lucrative first-person shooter. Call of Duty has sold 425 million copies in its lifetime. Comparatively, Battlefield has sold roughly 88 million copies as of 2018.