Apple announced last night that Steve Jobs, co-founder and chief executive of the company, would immediately resign from his position. Tim Cook, chief operating officer there, will replace him. In a public letter, Jobs said "I have always said if there ever came a day when I could no longer meet my duties and expectations as Apple’s CEO, I would be the first to let you know. Unfortunately, that day has come." Jobs will stay on at Apple as chairman of the board. Shortly after the news broke, Apple shares fell seven percent.