If the CEO posts a lie on Twitter, that misrepresents the stock, something he should know as a CEO, he is liable. So you are right, if it's on Twitter and the CEO posted it, it is public knowledge, and he can't post a blatant deceiving lie, so yes, it should be believed. If you think it is a lie and it is deceiving and you are financially hurt, you should take a screenshot and call a lawyer. They in turn would file a class action suit. I don't see any class action suits........
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