Semiconductor stocks are plunging Thursday after a major Wall Street firm and an executive at a large chip equipment company warned that memory chip demand is deteriorating versus expectations.
"Memory markets have worsened in recent weeks. For DRAM [memory chip], demand is weakening, inventory and pricing pressures are building, and vendors are struggling to move bits," Morgan Stanley analyst Shawn Kim said in a note to clients Thursday. "In NAND [flash memory], there is just too much supply. Earnings risks are emerging from 3Q and our cautious view on memory is playing out."
Last month the firm downgraded its rating to cautious from in line for the semiconductor industry, citing rising chip inventory levels.
Kim noted his recent conversations with semiconductor sales people and buyers, which revealed a increasingly negative environment for the memory market.

"All your three big drivers [PC, mobile, data center] for demand has worsened actually quite substantially in the last two weeks and will drive lower pricing into the third quarter. … Because of this lower demand, inventories are actually piling up [at Samsung and Hynix]," Kim said on a Morgan Stanley "Sound Bites" audio call Wednesday.
The iShares PHLX Semiconductor ETF declined 2.6 percent Thursday. Memory chipmaker Micron plunged more than 9.8 percent, while semiconductor equipment makers Applied Materials and KLA-Tencor dropped 5.2 percent and 9.7 percent, respectively.
KLA-Tencor shares fell to their lows for the trading session after its chief financial officer, Bren Higgins, gave an incrementally more negative appraisal of the memory chip market at a technology conference Thursday.
"Feels like [December quarter] will be up a little less than what we thought [due to the DRAM market]," he said at the Citi 2018 Global Technology Conference in New York, according to a FactSet transcript. "So, on the margin, modestly weaker, I think trajectory wise in the way we had laid it out [six weeks ago]."
Micron declined to comment on the Morgan Stanley report.
— CNBC's Patti Domm contributed to report.
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