General Mills stock tumbled in premarket trading Wednesday after the packaged-food company reported better-than-expected fiscal second-quarter earnings but lowered its fiscal-year outlook. General Mills reported net sales of $5.2 billion for the quarter ended Nov. 24, a 2% increase from the prior year and narrowly beating the FactSet consensus estimate of 5.1 billion. Shares of the company fell 3.7% to $63.50, however, after General Mills slashed its guidance for the fiscal year, citing “an uncertain macroeconomic backdrop for consumers across its core markets.”