Bloomberg, who was CEO of his financial information company before entering public life, has long said he values loyalty above all else among his employees and confidants.
"I've always thought that you, when you work for somebody, you have an obligation to not write a tell-all book afterwards, and that's true whether you're in an administration or whether you're working for a private company," he said.
BLOOMBERG: I HOPE MY AIDES DON'T WRITE TELL-ALL
At his multibillion-dollar financial information company, Bloomberg LP, there is a bit more of an insurance policy keeping mouths shut - employees sign confidentiality agreements upon being hired, according to a spokeswoman.
City Hall staffers do not sign such an oath. But the wealthy mayor, who was known for lavishing his top campaign aides with eye-popping bonuses after his election and re-election, could also similarly reward his city staff after he leaves office.