In a wild October for markets, these stocks were the biggest winners and losers

By Philip van Doorn

Many Big Tech stocks were hit hard but the S&P 500 showed strength under the surface, with a majority of stocks showing gains for the month

Intel was the worst-performing stock in the S&P 500 during October with a 43.5% decline, while Alphabet was down 18.5%.

October has seen a lot of carnage in tech stocks, but you might not guess that from the S&P 500's performance.

The S&P 500 SPX was down 0.5% for October through Friday morning, even though 75% of stocks in the large-cap benchmark index were up for the month.

The S&P 500 is about 40% concentrated in its largest 10 stocks by market capitalization. Meanwhile, the Invesco S&P 500 Equal Weight ETF RSP was up 5.5% for October - reflecting the underlying strength in stocks, even as many of the largest technology companies have fared poorly as investors question the AI infrastructure build-out. And as you can see below on the list of the month's worst performers, even non-IT companies, such as Caterpillar (CAT), were hit hard during what might be a temporary backlash against the rapid pace of data-center construction.

Among the largest 10 components of the S&P 500, Nvidia (NVDA) (the largest of all) was down 8.7% for October, while Alphabet (GOOGL) (GOOG) was down 18.5%, Amazon.com (AMZN) was down 6.9%, Broadcom (AVGO) was down 5.6%, Meta Platforms (META) was down 14.7% and Micron Technology (MU) was down 16.8%. (All price changes in this article exclude dividends.)

Also: Amazon's stock drops - even in the face of a bold new cloud forecast

Rounding out the largest 10 components of the index, Apple (AAPL) was up 4.2% for October through early trading Friday, while Microsoft (MSFT) was up 1.8% for the month, Tesla (TSLA) was up 10.5% and Eli Lilly (LLY) soared 23.5%.

One more Big Tech tidbit: SpaceX (SPCX) is not yet a component of the S&P 500, but its stock was down 8.6% for October through early trading Friday.

The S&P 500's best October performers

These were the 20 best-performing stocks in the S&P 500 for October, through early Friday:

 
Company                                      October price change  2026 price change  Decline from 52-week high 
PTC                                                         38.7%              11.7%                      -3.6% 
Accenture                                                   38.2%              -5.5%                     -12.9% 
Hasbro                                                      36.6%              46.0%                      -1.1% 
Crown Castle                                                34.5%               0.9%                      -5.9% 
Equifax                                                     34.0%             -15.3%                     -19.6% 
Roper Technologies                                          32.2%               3.8%                       1.3% 
Gen Digital                                                 30.2%               5.5%                      -9.4% 
Lockheed Martin                                             27.4%              34.2%                      -6.2% 
Charles River Laboratories International                    25.7%              85.9%                      -2.3% 
APA                                                         25.5%             113.1%                      -0.5% 
Pentair                                                     25.5%             -36.2%                     -39.6% 
Intuit                                                      23.5%             -48.6%                     -50.1% 
Eli Lilly                                                   23.5%              33.0%                       1.5% 
CDW                                                         23.2%              15.9%                      -5.0% 
Allegion                                                    22.9%              18.7%                       0.8% 
Gartner                                                     22.4%              -9.5%                     -11.1% 
Dow                                                         22.3%              44.0%                     -21.2% 
Norwegian Cruise Line Holdings                              21.9%             -19.9%                     -28.9% 
ConocoPhillips                                              21.5%              62.4%                      -0.5% 
FactSet Research Systems                                    21.1%              12.7%                      -3.8% 
                                                                                                Source: FactSet 

October's worst S&P 500 performers

Here were the 20 components of the S&P 500 that were down the most for October as of early trading on Friday:

 
Company                         October price change  2026 price change  Decline from 52-week high 
Intel                                         -43.5%              84.2%                     -52.3% 
Twilio                                        -36.1%              31.4%                     -39.4% 
Teradyne                                      -30.7%              43.6%                     -43.0% 
Sandisk                                       -30.0%             412.9%                     -48.3% 
Seagate Technology Holdings                   -29.4%             136.5%                     -43.1% 
Reddit                                        -29.3%             -56.2%                     -61.8% 
Lam Research                                  -26.7%              40.7%                     -45.1% 
Coherent                                      -26.0%              15.3%                     -51.6% 
Bloom Energy                                  -25.8%             136.4%                     -41.5% 
Robinhood Markets                             -25.5%             -25.9%                     -44.3% 
Comfort Systems USA                           -24.6%              33.7%                     -39.8% 
Skydance                                      -23.7%             -41.2%                     -54.1% 
Fortinet                                      -23.6%              72.1%                     -30.7% 
Dell Technologies                             -23.2%             228.1%                     -30.6% 
Caterpillar                                   -22.4%               9.8%                     -41.4% 
Marvell Technology                            -22.2%             141.8%                     -37.7% 
Applied Materials                             -22.0%              55.3%                     -46.1% 
Coinbase Global                               -21.7%             -35.5%                     -59.6% 
F5                                            -21.2%              37.4%                     -27.4% 
Super Micro Computer                          -21.1%              10.7%                     -40.1% 
                                                                                   Source: FactSet 

Intel (INTC) was the S&P 500's worst performer for October, with its shares plunging early Friday after the company disappointed investors with its revenue forecast.

Click on company tickers for more information about any stock, index or exchange-traded fund.

Don't miss: 11 bargain-priced stocks of companies that have huge growth potential over the next two years

-Philip van Doorn

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