Mayor Bloomberg's estimated worth has crept up to another $1.5 billion to $19.5 billion, according to Forbes magazine, but he still cannot claim to be the richest man in New York City.
Last year, billionaire oil tycoon David Koch, 71, knocked Bloomberg, 69, off the top of the list of richest New Yorkers, and he retains the title again this year.
Forbes calculates Koch's wealth at $25 billion.
He owns a 42 percent stake in Koch Industries, which has investments in pipelines, refineries, fertilizer and other products and does more than $100 billion in sales, according to Forbes.
Koch, a conservative contributor, is the 18th richest person in the world and the fourth wealthiest in the U.S.
Bloomberg, meanwhile, is the 30th richest person in the world and the 12th in the U.S. Forbes estimated his wealth at $18 billion in September 2010.
The Democrat-turned-Republican-turned-independent mayor stepped down as the head of his company before he ran for City Hall in 2001, but still owns an 85 percent stake in the financial information business.
He earns a $1 salary as mayor and gives away hundreds of millions a year to philanthropic causes.