The offering may happen this year and would likely value Groupon at a minimum of $15 billion, the sources told Bloomberg.

Groupon declined to comment on the report.

Groupon founder and Chief Executive Andrew Mason said in January that the company was considering a public offering and was in talks with bankers, but had had yet made a decision about whether to proceed.

A source said in January that a Groupon offering would be “meaningfully sized.”

The two-year-old start-up rebuffed a $6 billion advance from Google late last year, according to media reports.

Over the course of 2010 it grew to 50 million users, from 3 million, in 500 cities in 40 countries.