In this oddly specific example: Only if you had every reason to expect things would change, didn't warn anyone, and felt the need to blame the market for your actions. In that case, technically, yes, I would consider that dishonest.

But: To whom did you owe honesty to when buying stock? I'm not sure you owed honesty to anyone there.

When you hire people, you're making decisions that have impacts on their lives and those of their families. In the case of companies like Google, they're impacting entire communities.

So I would say they have a moral (if not legal) obligation to be more transparent with their workers about their intentions. But you, in this stock situation, would not have any moral obligation whatsoever.