USANA Down 5% After Short Seller, CNBC Separately Offer Negative News

USANA Health Sciences USNA fell six percent Tuesday after a reporter and a short seller separately suggested the company may be facing unwanted scrutiny in China.

CNBC reporter Herb Greenberg posted a tweet saying the company is the topic of an investigation by "Chinese business publications."

The tweet followed a report posted Tuesday by short-seller Andrew Left saying that "this week multiple media outlets in China have exposed the multi-level marketing schemes operated by USANA."

Left's report, on his Citron Research website, offered links to Chinese language sites, which he called "a must read for all investors."

Both Left and Greenberg have previously offered negative reports on USANA. The multi-level marketing company that provides nutritional supplements has also been the target of short sellers in the past.

Short interest currently accounts for about 1.6 million of USANA's 13.9 million shares outstanding.

USANA closed at $73.73, down 5.37 percent.

Multi-level marketing has recently proven controversial. In a widely published letter last month, Bill Keep, business dean of the College of New Jersey, asked the Securities and Exchange Commission to undertake an ongoing review of multilevel marketers.