Shares of Weight Watchers International (WTW) jumped more than 90% during Monday trading after the company announced its new partnership with billionaire media personality Oprah Winfrey. The partnership includes Winfrey purchasing shares worth 10% of Weight Watchers, as well as options for the talk show host to buy an additional 5% of the company down the road.

Winfrey will join Weight Watchers’ board of directors and she will also become a member of the company’s weight-loss program, sharing her experiences with her millions of fans. “I believe in the program so much I decided to invest in the company and partner in its evolution,” Winfrey said in the joint statement with Weight Watchers.

Weight Watchers stock jumped by more than half ahead of the opening bell Monday Morning — topping the $13-per share mark after closing Friday at $6.78 per share. The weight loss company is not the first brand to receive a boost from an association with Winfrey, who puts out an annual list of her “Favorite Things” to spotlight any number of products — from books and apparel to beauty products, electronics, etc. — many of which then experience a huge boost in popularity.

The boost from Winfrey’s investment comes at an important time for Weight Watchers, which had seen its stock fall more than 70% since the start of the year, and more than 90% since its all-time high in 2011. The membership in its weight-loss program has shrunk as an increasing number of people opt for free weight-loss apps, fitness wearables that come at a one-time cost, or a combination of both. Weight Watchers has historically turned to celebrity spokespeople to attract customers to its weight-loss program, with singer/actress Jennifer Hudson and Jessica Simpson each serving in that role recently.