Just days after his appointment to the board of Research In Motion, India-born Prem

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Watsa's company Fairfax Financial Holdings has increased stake in the Blackberry maker to 5.12 per cent.

Fairfax owns 26.85 million shares of RIM, maker of BlackBerry smartphone, representing 5.12 pc per cent stake in the company, up from 11.8 million shares in September, according to a filing with the US Securities and Exchange Commission.

Going by rough estimates, the stake buyout would have cost about $ 437 million Canadian dollars.

Earlier during the week, Watsa was named a RIM director as part of a management shakeup that included the replacement of co-Chief Executive Officers Jim Balsillie and Mike Lazaridis with former operating chief Thorsten Heins.