Corrects to say Bernstein upgraded the stock on Tuesday, not Wednesday, in the first two bullets and headline

** Memory chipmaker Western Digital WDC.O rises 3.4% to $279.60 premarket, extending gains from Tuesday when Bernstein upgraded to "outperform"

** Peers also extend gains: Seagate Technology STX.O up 2.5%, Sandisk SNDK.O gains 3.4% and Micron Technology MU.O advances 3.3%

** Memory stocks sold off last week after Google Research in a blog post announced TurboQuant, a compression algorithm that it says helps AI systems use much less memory without hurting performance

** WDC, STX, SNDK and MU have fallen between 8% and 15% since then, as of Tuesday's close

** Bernstein says "this however, should have zero impact on HDD demand and negligible impact on NAND demand. Given the stock sell-off we see this as an attractive entry point for STX, WDC and SNDK"

** Adds that demand and pricing continue to be better than expected on the back of AI for storage devices

** Up to last close, YTD gains are 57% for WDC, 42.3% for STX, 18.4% for MU and 167.6% for SNDK

(Reporting by Ragini Mathur in Bengaluru)

((Ragini.Mathur@thomsonreuters.com;))