* Private equity firms to pay about $3.1 billion-source
* Deal could be announced as early as Monday-source
(Recasts with new sourcing, adds background)
PHILADELPHIA, May 2 Private-equity firms Warburg Pincus and Silver Lake Partners are close to buying Interactive Data Corp IDC.N for about $3.1 billion, a source familiar with the situation said on Sunday.
The deal for IDC, the financial-market data provider controlled by publisher Pearson PLC, could be announced as early as Monday, said the source.
Pearson (PSON.L), which owns the Financial Times newspaper as well as the world's largest educational publishing business and Penguin Books, has a 61 percent stake in IDC.
IDC, which sells financial information and analytical tools to banks and financial institutions, said in January it was reviewing strategic options.
The company's business model allows for stable revenue, making it an attractive buyout target and giving banks the confidence to offer debt for the deal.
Other bidding groups included Kohlberg Kravis Roberts and CVC Capital Partners, and a team made up of Bain Capital and Advent International, sources previously told Reuters.
McGraw-Hill Cos Inc MHP.N dropped out of the auction last month, sources previously said.
Goldman Sachs (GS.N), which is representing the sellers, has suggested to potential buyers that it could offer debt financing at a multiple of 5.5-times to 5.75-times IDC's earnings before interest, taxes, depreciation and amortization, sources previously told Reuters.
The sources said other banks had suggested offering slightly higher leverage multiples -- up to 6 times.
Silver Lake declined to comment. IDC and Warburg Pincus could not be immediately reached for comment. (Reporting by Jui Chakravorty and Jessica Hall; Editing by Bernard Orr and Dhara Ranasinghe) (For more M&A news and our DealZone blog, go to here)