A glimmer of hope and a sexy partnership are apparently all it takes to propel a massive rally in shares of Best Buy Co.

The struggling retailer's share price has more than doubled this year, making it the top gainer in the S&P 500. Last month's quarterly results stoked hope that the company's battered business was stabilizing. More optimism spread on Thursday amid word of the company's expanded partnership with Samsung, news that sent the stock up as much as 13%.

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