2026-10-02 · STX
STX −12.0%: one of its biggest daily moves this year
Seagate Technology Holdings PLC moved 13.0 points less than its sector, on 2.6× its usual volume.
The story in plain words
Friday, October 2, 2026. STX −12.0%: one of its biggest daily moves this year. Seagate Technology Holdings PLC moved 13.0 points less than its sector, on 2.6× its usual volume.
What the data shows for Seagate Technology (STX): STX −12.0% today. Its sector fund (XLK) +1.1% today. S&P 500 (SPY) +0.7% today.
Worked out from that data: 13.0 points less than its sector. Volume 2.6× its 20-day average. Bigger than 98% of its daily moves over the past 250 trading days. After the 8 most similar STX days since Oct 14, 2021, the stock was higher 5 days later 1 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: Seagate Technology trades as STX and is part of the S&P 500, in the Information Technology sector (Technology Hardware, Storage & Peripherals), headquartered in Dublin, Ireland, founded in 1979.
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).
- OBSERVEDSTX −12.0% todayOct 2, 2026, 1:35 PM ET
- OBSERVEDIts sector fund (XLK) +1.1% todayOct 2, 2026, 1:35 PM ET
- CALCULATED13.0 points less than its sectorHow: stock return − sector fund return · Oct 2, 2026, 1:35 PM ET
- OBSERVEDS&P 500 (SPY) +0.7% todayOct 2, 2026, 1:35 PM ET
- CALCULATEDVolume 2.6× its 20-day averageHow: today’s volume ÷ average of the last 20 days · Oct 2, 2026, 1:35 PM ET
- CALCULATEDBigger than 98% of its daily moves over the past 250 trading daysHow: share of past daily moves smaller in size · Oct 2, 2026, 1:35 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 STX days since Oct 14, 2021, the stock was higher 5 days later 1 of 8 timesHistory, not a forecast. · How: same-company days with a move of similar size and direction
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Statistics only, not investment advice. Past moves don’t predict future ones. Data as of Oct 2, 2026, 1:35 PM ET.