Investors nervous about the future prospects for Disney and other older media companies sent its shares down 3.5 percent to $89.21 in after-hours trading. The media networks unit that includes ESPN, the Disney Channels and ABC recorded a 5.6 percent decline in operating income to $1.41 billion. Disney Chief Executive Bob Iger offered a spirited defense of ESPN on a conference call, describing an “uptick” in customers in the last couple months.