Fairfax Financial Holdings Ltd will buy another $250 million worth of BlackBerry Ltd’s convertible debentures, the companies said Wednesday, providing the struggling smartphone maker with much-needed cash.

The move by Fairfax, the Canadian property and casualty insurer run by investment guru Prem Watsa, will double the company’s holdings of BlackBerry’s debt. Fairfax also owns a 9.9 percent equity stake in BlackBerry, making it the company’s largest shareholder.

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

Other backers of the initial offering included an arm of Qatar’s sovereign wealth fund, Brookfield Asset Management , and Markel Corp. Canso Investment Counsel Ltd had bought $300 million.

The offering followed an aborted attempt by BlackBerry to sell itself amid spiraling losses and shrinking market share in the brutally competitive smartphone industry.

The Waterloo, Ontario-based company last month reported a massive quarterly loss as its newest devices have failed to catch on.

Before the deal BlackBerry carried no debt. Analysts noted the debt investment strengthened Fairfax’s influence over BlackBerry, but offered less downside risk than an increased equity investment would have.

The debentures pay a 6 percent coupon. The private placement could eventually increase the number of BlackBerry shares by almost 20 percent.

After excusing himself from BlackBerry’s board during its failed sale process after submitting a bid, Fairfax’s Watsa rejoined as lead director and head of its compensation committee when the initial offering was announced.

(Reporting by Allison Martell and Alastair Sharp; editing by Bernard Orr)