My wife is the VP of Internal Audit for a publicly traded company. During a recent audit, she discovered that the Chairman of the Board (who owns a majority stake in the co) has been having landscaping work done at his private home and having the company pay for it. Before becoming a public company, it was started and owned by the Chairman's family so this practice has been probably been going on for some time and it is likely that many corporate executives are aware of it. She is concerned that she could be fired or discriminated against if she comes forward with the information. The industry is a niche industry and she is also concerned that if terminated, she may be "blacklisted" and find it difficult to find employment at another company.
Whistleblower laws protect employees by prohibiting an employer from retaliating against an employee, because the employee engaged in some specific, protected conduct. Violating the prohibition may subject the employer to an award of damages, a civil penalty or even criminal sanctions, depending on the specific whistleblower law.
Federal and state laws provide numerous whistleblower protections. These laws vary on the conduct they protect and what constutes retaliation or reprisal. Many but not all require external, as opposed to internal, reports. Most require the employee to have been subjected to some tangible, adverse employment action. The fear of retaliation or reprisal is not usually enough.
Your wife should consult with an attorney licensed to practice in your state to discuss the particulars of her matter and for specific legal advice.