TORONTO—The new chief executive of BlackBerry maker Research In Motion Ltd. is overhauling the company's executive ranks and exploring strategic options, including a sale of the struggling smartphone pioneer.

The changes include the exit of longtime executive Jim Balsillie, who had presided over RIM's rise and steep fall. Mr. Balsillie, who until earlier this year was co-CEO, resigned his board seat and is parting ways with a company he helped run for 20 years.

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