VISIT CNBC.COMX The Definitive Guide to Business The Definitive Guide to BusinessWhat Facebook CEO Mark Zuckerberg is more afraid of than screwing up his $438 billion company Catherine Clifford Friday, 26 May 2017 | 8:20 AM ET CNBC.com Getty Images Mark Zuckerberg SHARES Facebook founder and CEO Mark Zuckerberg runs a public company with a market cap...