The Mexican billionaire Carlos Slim is close to a deal to pump $250m (£172m) into the New York Times's parent company as the newspaper publisher struggles with a shrinking readership and the imminent expiry of a loan facility.

Slim, who already owns a 6.4% stake in the New York Times Company, is to get 10-year notes with warrants convertible into shares. He could also receive special dividends with a return of up to 10%, according to a report in the NYT's own business section.

A dominant player in Mexico's telecommunications industry, Slim is estimated by Forbes magazine to be the world's second-richest man with a fortune of $60bn, second only to Warren Buffett.

The NYT Company, which also owns the Boston Globe and the Herald Tribune, lost $2m on continuing operations in the third quarter of 2008, although it made a bottom-line profit after an $8.6m gain on the sale of nine television stations.

Nicknamed the "Grey Lady", the NYT is struggling with recession-hit advertising and waning sales - its daily circulation dropped by 3.6% to just over 1m in the six months to September.

The publisher has two $400m credit facilities, one of which expires in May, prompting speculation about the stability of its finances. The NYT is negotiating a sale and leaseback to borrow $225m against its office near Times Square.

John Morton, a newspaper analyst, said the level of return reportedly offered to Slim was significant: "The fact that there's interest in borrowing money at a very substantial interest rate indicates that they're under some stress."

A spokeswoman for the NYT declined to comment. But the publishing company reacted angrily last week to a report in the magazine Atlantic Monthly that suggested that it could default on its loans. "While credit markets remain tight, we have been talking with lenders and, based on our conversations with them, we expect to get the financing to meet our obligations when they come due," said the NYT in a letter to the Atlantic Monthly.

It added that it was only using $400m out of its total $800m in available credit, and therefore does not need to replace the whole of its expiring facility.