Which Company Racked Up a Growth Rate of 23,646 Percent?
Oleg Firer
Oleg Firer | Facebook

Inc. Magazine and Inc.comreleased their annual Inc. 5000 list this week, ranking the fastest-growing private companies in the U.S.

Topping the list is payment processor Unified Payments with a three-year growth rate of — yes, you are reading this correctly — 23,646 percent.

Oleg Firer co-founded Unified Payments in 2007 at age 29. The company now processes $10 billion worth of transactions for 100,000 merchants a year, and it’s growing quickly.

Unified Payments isn’t alone, though. Despite the tough economy, the median three-year growth of 2012 Inc. 500 companies was 1,436 percent — the highest rate in the list’s 31-year history, according to Inc. (More:Secrets of Venture Capitalists)

When the list debuted, Firer, 35, was a boy living in Ukraine. He arrived in Brooklyn, New York, at age 12 and grew up in the borough’s Brighton Beach neighborhood. He started his first business, a cell phone retailer, at age 17. His immigrant family didn’t have much money when he was growing up; as a result, Firer focused on working hard.

“I got where I am because I wouldn't take no for an answer,” said Firer, who now lives in Miami with his family and drives a Bentley to work. “I always remember where I came from and that I could end up back there with nothing.”

The Inc. 5000 2012 honorees, in aggregate, generated $299 billion in 2011 revenue and created 389,000 jobs over the last three years, according to Inc. Prominent brands on the list include Facebook , Yelp , yogurt maker Chobani, and

Companies on the list span 25 industries, all 50 states, and metro areas ranging from Boston to San Diego. New York City had the most honorees, with 350 — three more than runner-up Washington, D.C. While nearly half the winners had revenues between $2 million and $10 million, more than 50 took in over $1 billion.

There were 39 companies that went public in 2012; they include Audience , Millennial Media , Brightcove, Annie's , and Tumi Holdings .

The five-year-old Inc. 5000 list is an expansion of the better-known Inc. 500 list, which was introduced in 1982 to showcase the fastest-growing private companies. (More:Meet the Business Owner Who's Speaking at the RNC)

The 2012 Inc. 500 and Inc. 5000 are ranked according to percentage revenue growth when comparing 2008 to 2011. To qualify, companies must have been founded and generating revenue by March 31, 2008. They had to be U.S.-based, privately held, for profit, and independent — not subsidiaries or divisions of other companies — as of December 31, 2011. (Since then, a number of companies on the list, including Facebook, have gone public or been acquired.) The minimum revenue required for 2008 is $100,000; the minimum for 2011 is $2 million.