Facebook shares fell by 2.4 percent on Friday after the New Zealand massacre during which the terrorist live-streamed his killing spree.
Shares dropped to $165 by the end of the day, a minor improvement on the $162 they hit at the worst point in the day.
The decrease also coincided with the departure of Chief Product Officer Chris Cox and WhatsApp Vice President Chris Daniels.
Cox, a Wall Street favorite who has worked with Facebook founder Mark Zuckerberg for 13 years, led the social network's business development team and helped define the business model of its messaging service WhatsApp.
Facebook's shares were down by 2.4 percent by the end of trading on Friday after struggling all day
'We believe Cox played a critical role in establishing FB's mission, values, and culture, and he was extremely well-regarded inside and outside the company, including by Wall Street,' JPMorgan analysts wrote in a research note.
Also departing is WhatsApp Vice President Chris Daniels, adding to a string of recent high-profile exits from Facebook's product and communications teams.
Facebook, Twitter and Google were also facing another round of public discussions over extremist content on their platforms on Friday, after video footage of mass shootings in New Zealand was live streamed and widely shared online.
'The live-streaming of New Zealand's shooting will certainly bring on more questions of regulation and scrutiny over Facebook. It helped provide a platform for today's horrific attack and will undoubtedly be called into question for facilitating the spread of this,' said Clement Thibault, analyst at global financial markets platform Investing.com.
New Zealand shooter Brendon Tarrant live streamed his massacre at a Christchurch mosque on Facebook
The gunman, who was part of attacks that killed 49 people in New Zealand, broadcast live footage on Facebook of the attack on one of the mosques, leading to calls for more content moderation by the social network.
Chief Product Officer Chris Cox resigned on Thursday
Britain's interior minister Sajid Javid said social media firms must take action to stop extremism on their channels after Friday's shootings.
'You really need to do more @YouTube @Google @facebook @Twitter to stop violent extremism being promoted on your platforms,' Javid wrote on Twitter.
The social media companies have said they would take down content involving the mass shootings, which were posted online as the attack unfolded.
Facebook has been investing heavily to weed out fake content from its platform and has hired thousands of employees for moderating content and suspended hundreds of suspicious accounts in different countries.
The company's shares were down 2.5 percent at $165.83 in midday trade.
Cox joined 13 years ago and helped create Facebook's News Feed feature.
Less than a year ago, he was put in charge of all of Facebook's apps, including its flagship social media site as well as Instagram, WhatsApp and Messenger.
Reversing course, Facebook will not appoint a direct replacement for Cox. Instead, the leaders of each app will report to Zuckerberg.
Cox penned a post to his personal Facebook page announcing his departure.
WhatsApp Vice President Chris Daniels also stepped down on Thursday