Tyson Foods Inc., the largest U.S. meat processor, had its stock rating raised by an analyst at CLSA who said a class-action complaint alleging price collusion among chicken producers was "baseless" and that investors should buy the company’s stock on strong pork and beef margins.

“Investors should take advantage of the unsubstantiated noise,” CLSA’s Jeremy Scott said in a note, raising his recommendation to buy from outperform. “The complaint is compelling only in its fiction and misrepresentation of the market and the facts. We’re confident in a positive outcome" for Tyson.

Shares of Springdale, Arkansas-based Tyson tumbled 8.9 percent Friday after a report from Pivotal Research Group analyst Tim Ramey said the lawsuit was "convincing." Ramey revised his rating to sell from buy and cut his stock-price target to $40 from $100. The shares were up 3.5 percent at $70.13 at 9:47 a.m. in New York.

The lawsuit in question was filed in Illinois district court on Sept. 2 and says that starting in 2008, broiler-chicken producers including Tyson colluded by sharing proprietary data and raising fewer chickens, constraining supply. The allegations assert that most of the $30 billion U.S. chicken industry engaged in the scheme, resulting in consumers paying 50 percent more. Tyson said in a statement Friday it disputes the allegations, and the conclusions reached by Ramey.

The plaintiff in the complaint is paying the same for chicken today on a nominal, per-pound basis as it was in 2008, when the collusion allegedly began, CLSA’s Scott said. Retailers paid about 70 cents a pound for chicken in the past 12 months, according to U.S. government data, down 1 percent from 2008, he said. In comparison, beef is up 40 percent and pork up 20 percent over the same period, Scott added.