After a dozen years as mayor, Michael Bloomberg is again a private citizen, and one of the city's richest. But you won't find his name on his company's own index of the wealthiest individuals.

Bloomberg News has a policy of not covering its parent company, Bloomberg LP.

That means that Michael Bloomberg is nowhere to be found on his own company's index of the richest Americans. He was #10 on the Forbes Magazine rich list.

All this underscores the closing of an unusual, 12-year window to put questions to a man whose fortune is estimated at around $30 billion dollars.

In 2010, David Letterman put it to Bloomberg plainly: “How did you manage to get so damn rich?”

Bloomberg replied that he started Bloomberg LP after getting fired from an investment bank.

Now that he’s no longer Mayor, Bloomberg is turning his attention back to the company that made his fortune.