Yes, but they'd also face criminal prosecution for stock manipulation. As McCarthy points out, they have legal obligations as defined by SEC regulations and US Code, to report material financial events. Obamacare certainly qualifies. And these aren't insignificant consequences for not disclosing these adverse events. The civil and criminal penalties can be hefty.
Your point is excellent. Right now is not a good time to be a CEO. They are between a rock and a hard place.