Depends on the type of employer. Mine certainly won't be selling any data to anyone. Their whole business model is trustworthiness & they're not going to wreck their (profitable) business model for a couple of bucks from selling data.
Except if they get acquired, or go public, or go out of business and are liquidating assets, or just change their minds. You don't need to trust them with your data if they don't collect it and they don't need to collect if for you to do your job effectively.