Microsoft co-founder Bill Gates recently discussed his “greatest mistake ever” while running the company when he sat down for an interview at Village Global with Eventbrite CEO Julia Hartz.

In full, Gates said, “the greatest mistake ever is whatever mismanagement I engaged in that caused Microsoft not to be what Android is.” According to Gates, this was a mistake that cost the company roughly $400 billion.

For reference, Microsoft tried to dive into the mobile space by launching the first Windows Mobile phone in 2002. This was before Google acquired Android in 2005, before Apple debuted the iPhone in 2007, and before the first commercial Android phone launched in 2008.

Source: MSN