Shares of Abbott Laboratories dipped 0.6% to $108.77 Tuesday afternoon after the U.S. Food and Drug Administration issued a warning letter to Abbott Diabetes Care. The letter, dated Jan. 23, criticized the company’s process for verifying the accuracy of its FreeStyle Libre continuous glucose monitors. Specifically, the FDA said Abbott failed to ensure key accuracy specs were passed to third-party manufacturers and released finished devices without conducting accuracy tests at launch. Abbott has 15 business days to respond. Earlier, the stock had fallen as much as 2.9%.