Costco Slide Deepens As Deutsche Joins Goldman With Downgrade By: TalkMarkets June 19, 2017 at 15:10 PM EDT The shares of Costco are declining after Deutsche Bank downgraded the stock today, citing increased competition and fading catalysts. Read More >> Related Stocks: Amazon.com American Express Costco Wholesale Visa Wal-Mart Stores, Inc. Whole Foods Market