Ontario-based Fairfax Financial Holdings Ltd. on Wednesday said that it would buy another $250 million worth of BlackBerry Ltd.'s convertible debentures. The deal will provide the struggling smartphone maker with much-needed cash.

According to a report by Reuters, Fairfax's move will double its holdings of BlackBerry's debt. It also owns a 9.9% equity stake in BlackBerry, making it the company's largest shareholder. Fairfax is a Canadian property and casualty insurer run by investment guru Prem Watsa.

Fairfax is exercising a previously announced option linked to BlackBerry's recent $1 billion debt financing, in which it had initially bought $250 million, the report said.

Other backers of the initial offering included an arm of Qatar's sovereign wealth fund, asset manager Brookfield Asset Management Inc. and insurance holding company Markel Corp. Canso Investment Counsel Ltd. had also bought $300 million of BlackBerry's debt, Reuters said.

The debt financing deal followed an aborted attempt by BlackBerry to self itself amid spiralling losses and shrinking market share in the brutally competitive smartphone industry, the report said.