2026-10-02 · WDC
WDC −11.1%: an unusually large move for this stock
WESTERN DIGITAL CORP moved 12.1 points less than its sector, on 2.6× its usual volume.
The story in plain words
Friday, October 2, 2026. WDC −11.1%: an unusually large move for this stock. WESTERN DIGITAL CORP moved 12.1 points less than its sector, on 2.6× its usual volume.
What the data shows for Western Digital (WDC): WDC −11.1% today. Its sector fund (XLK) +1.0% today. S&P 500 (SPY) +0.7% today.
Worked out from that data: 12.1 points less than its sector. Volume 2.6× its 20-day average. Bigger than 96% of its daily moves over the past 250 trading days. After the 8 most similar WDC days since Oct 14, 2021, the stock was higher 5 days later 4 of 8 times (History, not a forecast).
Possible contributors. These line up in time with the move; they are not confirmed causes: News: “Curious about which S&P500 stocks are generating unusual volume on Friday? Find out below.” (Published around the move. Timing only, not a confirmed cause). News: “Friday's session: top gainers and losers in the S&P500 index” (Published around the move. Timing only, not a confirmed cause).
About the company: Western Digital trades as WDC and is part of the S&P 500, in the Information Technology sector (Technology Hardware, Storage & Peripherals), headquartered in San Jose, California, founded in 1970.
This is one of CookieStocks’ daily stock stories about unusually large one-day price moves in S&P 500 stocks, measured against each stock’s own history, its sector and its usual volume. Stories are found automatically each trading day from market data and SEC filings, and every claim is labelled as observed, calculated or a possible contributor. Statistics only, not investment advice.
Prove it
Every claim on the graphic, labelled: observed (straight from the data), calculated (worked out from it), or possible contributor (lines up in time, not a confirmed cause).
- OBSERVEDWDC −11.1% todayOct 2, 2026, 2:05 PM ET
- OBSERVEDIts sector fund (XLK) +1.0% todayOct 2, 2026, 2:05 PM ET
- CALCULATED12.1 points less than its sectorHow: stock return − sector fund return · Oct 2, 2026, 2:05 PM ET
- OBSERVEDS&P 500 (SPY) +0.7% todayOct 2, 2026, 2:05 PM ET
- CALCULATEDVolume 2.6× its 20-day averageHow: today’s volume ÷ average of the last 20 days · Oct 2, 2026, 2:05 PM ET
- CALCULATEDBigger than 96% of its daily moves over the past 250 trading daysHow: share of past daily moves smaller in size · Oct 2, 2026, 2:05 PM ET
- POSSIBLE CONTRIBUTORNews: “Curious about which S&P500 stocks are generating unusual volume on Friday? Find out below.”Published around the move. Timing only, not a confirmed cause. · Oct 2, 2026, 1:05 PM ET
- POSSIBLE CONTRIBUTORNews: “Friday's session: top gainers and losers in the S&P500 index”Published around the move. Timing only, not a confirmed cause. · Oct 2, 2026, 12:35 PM ET
- CALCULATEDAfter the 8 most similar WDC days since Oct 14, 2021, the stock was higher 5 days later 4 of 8 timesHistory, not a forecast. · How: same-company days with a move of similar size and direction
More stories
Market wrap: S&P 500 +0.7%, a positive day2026-10-02
DAL: shares down while sales grow2026-10-02
TER +8.0%: an unusually large move for this stock2026-10-02
HPE +8.3%: an unusually large move for this stock2026-10-02
MKC: shares down while sales grow2026-10-02
NTAP +7.7%: one of its biggest daily moves this year2026-10-02
Statistics only, not investment advice. Past moves don’t predict future ones. Data as of Oct 2, 2026, 2:05 PM ET.