Shares of Micron Technology Inc. are down 4.5% in premarket trading Wednesday after Goldman Sachs analyst Mark Delaney downgraded the stock to neutral from buy. While he's not making call on Micron's fiscal fourth quarter results, which are due out on Sept. 20, he believes that the company's gross margins will decline sequentially from that quarter through the middle of calendar year 2019. "Our view of margin declines is due to lower memory ASPs, both from more challenging DRAM [supply and demand] conditions and also NAND oversupply," he wrote.