Facebook has lost almost $60 billion in value since the CA story broke. If you’re an investor, and this information wasn’t publicly available to you, you might feel aggrieved and want to seek compensation.
Facebook is a public company. They have strict rules related to informing stock owners and insider trading.
Investors should be able to win a lawsuit if they can prove that company did not immediately disclsee important information, falsified information or that some owners were privy to insider information when they traded (Zuk sold his shares in suspicious time).
If you read the article a bit further, you might find the explanation:
>Zuckerberg's sales accounted for the most, by far. He announced plans in September to sell 35 million to 75 million shares over the next 18 months to fund philanthropic efforts.
It's not new and was announced in September 2017.
From the same article:
>CEO Mark Zuckerberg sold 1.14 million shares as part of regularly scheduled programs.
The whole discussion surrounds events that occurred long before September 2017, which is why this is interesting. Previous articles indicated that the company, and likely Zuckerberg himself, was aware of part of the situation in 2015 and found out more in 2016 / early 2017. If it can be established that he knew about it, the 2017 September sales announcement is arguably tainted.