The Qatari sovereign wealth fund bought as much as $200 million of the offering, in which Fairfax Financial Holdings Ltd, BlackBerry Ltd's largest shareholder, has itself put in $250 million.
The embattled smartphone maker BlackBerry Ltd abandoned plans on Monday to sell itself and replaced its chief executive, sparking a 16 percent drop in its share price. It said it would raise $1 billion by issuing convertible notes to a small group of long-term investors, including Fairfax, which is run by investment guru Prem Watsa.
The source said the Qatari fund was attracted to invest in the BlackBerry Ltd debt offering because of the size of the coupon offered.
A spokesman for Qatar Holding declined to comment. Fairfax and BlackBerry Ltd declined to identify other investors in the debt offering.
In recent years, Qatar Holding, the investment arm of the Gulf state's sovereign wealth fund, has emerged as one of the world's most prolific investors. It has bought stakes in large blue-chip names such as oil giant Royal Dutch Shell, jewelry maker Tiffany & Co and Germany's Siemens as it deploys the riches from country's plentiful natural gas reserves.
The fund, which is said to have an investment capacity of $30 billion to $40 billion every year, has been searching for investments in debt instruments that offer returns greater than plain vanilla bonds, according to bankers and asset managers doing business with the firm.
Qatar Holding has previously invested in contingent-convertible bonds issued by Swiss lender Credit Suisse and also participated in a 1.2 billion euros convertible bond offering by German automaker Volkswagen in June this year.
The fund has built a $1 billion stake in Bank of America Corp and also recently invested $200 million in Samsung Electronics.