Shares of Weight Watchers are soaring thanks to Oprah Winfrey's magic touch.
The stock was up as much as 19 percent in intraday Thursday trading, and rose more than 8 percent Friday, to $12 a share. The rally comes in reaction to an advertisement by TV star and major Weight Watchers shareholder Winfrey, in which she says that she she has lost 40 pounds thanks to the company's weight loss program.
Michael Khouw of Optimize Advisors pointed out Thursday on CNBC's "Fast Money" that around 11,000 call options on Weight Watchers traded during the day — some 10 times the stock's average. In one notable trade, a trader bought 1,200 of the February 13-strike calls for 65 cents a share. This means that the trader sees Weight Watchers closing above $13.65 upon mid-February expiration.
The stock's last big spike took place in October 2015, when Winfrey first announced that she was going to take a stake in the company. The stock then jumped about 170 percent over the course of four days, taking it as high as $28.05.
Despite the recent gains, then, the share price would still have to more than double in order to reach those lofty levels.