WATERLOO, Ont. -- The chairman and CEO of Fairfax Financial Holdings has boosted his holdings in Research In Motion, a show of confidence in the struggling BlackBerry maker.

Prem Watsa has increased his holdings in the struggling BlackBerry maker to 9.9 per cent -- representing 51.9 million shares -- a filing with the U.S. Securities and Exchange Commission shows.

That values his most recent stock investment at about $356 million based on the closing price of RIM's shares Friday on the Toronto Stock Exchange.

Watsa had held about five per cent of the Waterloo, Ont., company, and has said a turnaround for RIM would take three to five years, making his investment in the BlackBerry maker a long-term one.

Chief executive Thorsten Heins recently announced that RIM will cut about 5,000 jobs as it slashes costs across the organization to contend with faltering sales. The BlackBerry maker has been losing market share to Apple and Android smartphones, especially in the consumer-savvy North American market.

Heins took over from former co-CEOs Jim Balsillie and Mike Lazardis in January.

Shares of RIM were down seven cents to $6.80 on the Toronto Stock Exchange.