Food and Drug Administration Commissioner Scott Gottlieb called out Walgreens Boots Alliance Inc.'s /zigman2/quotes/203410933/composite WBA -1.14% pharmacy stores as the "top violator" among pharmacies illegally selling tobacco products to minors, and has sent a letter to management requesting a meeting. Gottlieb said in all, 15 national retail chains have been identified with "disturbingly high rates of violations," including Dow Jones Industrial Average /zigman2/quotes/210598065/realtime DJIA -0.95% components Exxon Mobil Corp. /zigman2/quotes/204455864/composite XOM -0.78% , Chevron Corp. /zigman2/quotes/205871374/composite CVX -0.53% and Walmart Inc. /zigman2/quotes/207374728/composite WMT -0.58% ,as well as Kroger Co. /zigman2/quotes/206215053/composite KR -2.01% , Marathon Oil Corp. /zigman2/quotes/205031829/composite MRO -2.16% , Sunoco L.P. /zigman2/quotes/208614298/composite SUN +1.12% and Casey's General Stores Inc. /zigman2/quotes/208156554/composite CASY +0.45% . "Companies should be on notice that the FDA is considering additional enforcement avenues to address high rates of violations," Gottlieb said in a statement. He said the FDA has also sent letter to more than 40 companies seeking information about more than 50 products, including e-cigarette products, that are being illegally marketed, citing concerns that these companies are attempting to capitalize on the "troubling popularity" of Juul Labs Inc.'s e-cigarettes. In December, Altria Group Inc. /zigman2/quotes/208895754/composite MO +0.11% announced a $12.8 billion equity investment in Juul.