This happened years ago. But my experience as being a whistle blower may still be relevant.
CEO and his key GM pushed a strategy and investment programme through the Board that substantially disadvantaged the parent company, but somehow failed to point this out to the parent company. I met with the Director of Strategy in the parent company and briefed them as to what was going on.
About 3 days later the entire company (except me) was sent an email from the “key” GM telling them not to talk to me as information was being leaked outside the company by me.
I found out because a colleague managed to accidentally print a copy of the email and leave it on my desk.
Once the immediate shock died away I booked in with a meeting with a employment lawyer. Later that day we met and he was as eager a a hungry greyhound seeing a wounded rabbit.
One lawyer's letter later and the HR director from the parent company meet with us offering $$$$ or a better job in the parent company. The sweetener was that we were also told that the CEO and the GM had both resigned from the subsidary company. The lawyer said your call: litigate, accept compensation or get a new job.
I took the job as an executive. 3 years later I was made redundant. It probably was the best job I've ever had, but I still wonder whether I should have taken the cash.
Anyway, back in the original company my name was dirt for years. If I bump into my old colleagues they want to know what went on back then.
I think I would still be a whistle blower but it costs a lot in terms of stress, industry credibility and future employment. So going straight into a better job in the parent company was a of restoring my credibility in most parts of the industry.
I think that most HR departments would shit upon whistle blowers but it was lucky that I had a fairy godmother in the form of the Director of Strategy.