Shares of Kellogg (K) - Get Report sank Thursday as investors were spooked by the company's weaker-than- expected guidance for 2020.

Kellogg's stock price plunged 6.5% to $64.85 a share after the maker of Frosted Flakes, Pop-Tarts and Pringles forecast a 3% to 4% decline in earnings per share on an adjusted basis for 2020.

Analysts surveyed by FactSet had been expecting a 3.6% increase in Kellogg's 2020 earnings to $4.03 a share.

Even so, Kellogg's numbers for the fourth quarter of 2019 beat analysts' estimates.

Kellogg reported earnings per share of 91 cents, a cut above the 86 cents that analysts surveyed by Zacks Investment Research had expected. Kellogg also scored a slight beat on revenue, generating $3.22 billion for the last three months of 2019, compared with the $3.19 billion forecast by analysts.

A year earlier, Kellogg's net sales were $3.32 billion.

The stock price turbulence comes as Kellogg moves ahead with an ambitious restructuring plan.

The company sold off its fruit snacks, pie crust, cookies and ice cream cones businesses last July, which, in the short-term at least, has hurt earnings, while it also struggles with "higher input costs," Zacks noted.

However, the Pringles brand, the nutrition bar RXBAR, and an investment in Nigerian food distributor Multipro have been bright spots on Kellogg's balance sheet, according to Zacks.

"By executing our Deploy for Growth strategy, we posted sales growth for the full year," said Steve Cahillane, Kellogg's CEO and chairman.