Best Buy Chief Financial Officer Sharon McCollam's determined campaign to court new investors appears to be paying off.

Over the past several months, McCollam along with CEO Hubert Joly have traveled throughout the country, trying to sell Best Buy's comeback story. And some large institutional investors have been buying.

Hometown investment firm Winslow Capital Management Inc. recently purchased 12.1 million shares in Best Buy, according to a Securities and Exchange Commission filing this week. The Minneapolis-based company, made up of veterans from Piper Jaffray and Thrivent, is now the sixth-largest Best Buy shareholder. Winslow oversees a stock portfolio worth over $30 billion, including shares in Apple, Amazon and Salesforce.com.

Earlier this year, Wellington Management Co. acquired 22 million shares, according to SEC documents, making the Boston-based investment firm the third-largest shareholder in Best Buy.

Wellington's investment has already paid off. The firm sold nearly 4 million shares between March and June as Best Buy stock rose from $25 to $30 a share.

Founder and chairman emeritus Richard Schulze remains Best Buy's largest shareholder with over 70 million shares, or a 20.63 percent stake in the world's largest consumer electronics retailer.

Winslow and Wellington executives could not be reached for comment. Best Buy officials declined to comment.

Investors' new enthusiasm for Best Buy stands in stark contrast to last year, when the company's stock was heavily shorted as the retailer's sales and cash flow plummeted. At one point, Best Buy stock hit $11.20 in early December, down from over $50 just a couple of years previous.

Since then, institutional investors like Putnam and Ameriprise have sold off their stakes. Today, Best Buy is one of the hottest stocks in the S&P 500 index, outperforming rivals Apple and Amazon, due to stabilizing sales and cost cutting. The company closed Friday at $30.37.

Best Buy reports second-quarter earnings on Tuesday. Analysts expect the company to report flat to slightly positive sales at stores open at least a year. However, they also estimate Best Buy's profits will fall 40 percent compared with the same period in 2012 because the retailer is matching competitors' prices.

"While we believe [Best Buy] is a viable business with a strong new management team, it operates in a volatile industry with both competitive and product cycle challenges still remaining," Morgan Stanley said in a report this week.

Thomas Lee • 612-673-4113