I'm not sure you understood my comment. The point of my comment was that with respect to housing sales, sellers have responsibilities with regards to things not covered by the sales contract because the law says they do. It's so not the point as to whether they are state or federal laws (but on that note, the "federal disclosure laws" specifically only apply to the use of lead-based paint in housing built before 1978, or in other words, to less than 25% of the US housing market).
There are no similar laws that govern corporate acquisitions. If an acquisition agreement does not explicitly (or by incorporation) require a disclosure about "X" , then the lack of disclosure about "X" has absolutely no impact on the resolution of the parties' respective contractual obligations.
And yes, nothing protects a company from not disclosing material information regardless of “due diligence”, including fraud. So give it up.