Shares of Starbucks dropped 1.4 percent in extended trading, after Executive Chairman Howard Schultz announced he would be stepping down effective June 26. Schultz has played an essential role in the success of the coffee company, serving as CEO from 1987 through 2000 and again from 2008 through 2017, when he resigned from the position to be replaced by Kevin Johnson. Schultz’s decision comes about a week after Starbucks closed for an afternoon for company-wide sensitivity training following the arrest of two black men in a Philadelphia Starbucks. Shares of Twitter jumped as much as 5 percent in extended trading, after it was announced that the social media company would replace seed-maker Monsanto on the S&P 500. The changes will go into effect on Thursday, as the German pharmaceutical company Bayer moves to complete its buy-out of Monsanto. Shares of Portola Pharmaceuticals fell 2.9 percent after the bell. The biotechnology company announced CEO William Lis will retire August 1, after which he will remain on in an advisory role. Portola’s board appointed Dr. John Curnutte and Mardi Dier as interim Co-presidents. Coupa Software shares whipsawed in after hours trading before ending up 0.5 percent. The enterprise software company reported a first quarter loss per share of 1 cent on revenue of $56.4 million, according to Thomson Reuters. Coupa forecast a loss per share of 8 to 10 cents on revenue of $56 million to $57 million revenue for the second quarter of fiscal 2019. Shares of Aegean Marine Petroleum Network plunged more than 40 percent in extended trading. The marine fuel logistics company released the initial findings of an internal audit, kicked off in May to investigate the preparation of last year’s annual report. Based on preliminary findings of the review, the committee estimates about $200 million owed to Aegean will need to be written off. Aegean said a number of individuals thought to be involved have been terminated or placed on leave.