Bloomberg reported Thursday that Chinese operatives were able to insert malicious microchips in motherboards made by Super Micro Computer Inc. SMCI, -30.61% a company from which Apple Inc. AAPL, -1.05% and Amazon.com Inc. AMZN, -1.03% units bought products. The report says that microchips not part of the original motherboard design were found by Apple as well as by a third party that was looking into the security of Elemental, a company that Amazon eventually acquired. Bloomberg said that hardware hacks are often difficult to pull off but can have dire consequences if successful. The report cites numerous anonymous sources. Amazon.com, Apple, Super Micro, and the China’s Ministry of Foreign Affairs denied the report in statements provided to Bloomberg. Super Micro shares are down 11% in premarket trading Thursday, while Apple’s stock is down 0.7% and Amazon’s is off 0.3%. Apple shares have gained 51% over the past 12 months, while the Dow Jones Industrial Average DJIA, -0.48% has risen 18%.

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