TORONTO – Fairfax Financial Holdings Ltd. (TSX:FFH) is increasing its investment in BlackBerry Ltd. (TSX:BB) with the purchase of an additional US$250 million in convertible debentures.

The move, announced Wednesday, comes as BlackBerry shares have had a strong start to the year, gaining more than 15 per cent since the end of 2013.

Shares in the company were up six cents at $9.20 in trading on the Toronto Stock Exchange on Wednesday afternoon.

Fairfax said it would exercise an option top buy the debentures in connection with a $1-billion financing announced by the smartphone maker late last year.

The insurance and investment firm invested $250 million as part of the original deal along with Canso Investment Counsel Ltd., which invested $300 million.

Funds managed by Mackenzie Financial invested $200 million, $100 million came from Qatar’s sovereign wealth fund, $70 million from Virginia-based Markel Corp., $70 million from funds Managed by Manulife Financial Corp. (TSX:MFC) and $10 million from Brookfield Asset Management of Toronto (TSX:BAM.A), according to securities filings.

Fairfax said the additional BlackBerry debt was being bought for investment purposes.

The debentures pay six per cent interest and are convertible into BlackBerry shares at a price of $10 per share.