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 45.3% decline, while Alphabet was down 18.7%.

October brought 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 declined 0.9% for October, even though 72% 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. And while the index was down, the Invesco S&P 500 Equal Weight ETF RSP was up 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 10.4% for October, while Alphabet (GOOGL) (GOOG) dropped 18.7%, Amazon.com (AMZN) declined 3.5%, Broadcom (AVGO) was down 7.1%, Meta Platforms (META) was down 15.2% and Micron Technology (MU) fell 16.9%. (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) rose 3.5% for October through, while Microsoft (MSFT) was up 1.8% for the month, Tesla (TSLA) was up 12.7% and Eli Lilly (LLY) soared 22.5%.

One more Big Tech tidbit: SpaceX (SPCX) is not yet a component of the S&P 500; it's stock declined 10.7% during October.

The S&P 500's best October performers

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

 
Company                       October price change  2026 price change 
Accenture                                    40.8%              -3.7% 
PTC                                          39.4%              12.2% 
Hasbro                                       35.8%              45.2% 
Equifax                                      34.5%             -14.9% 
Roper Technologies                           33.5%               4.8% 
Crown Castle                                 33.1%              -0.2% 
Gen Digital                                  32.3%               7.1% 
APA                                          27.2%             115.9% 
Dow                                          26.0%              48.4% 
Lockheed Martin                              25.1%              31.7% 
Pentair                                      25.0%             -36.4% 
Tyler Technologies                           23.8%             -13.1% 
Intuit                                       23.7%             -48.5% 
ConocoPhillips                               23.1%              64.5% 
GoDaddy                                      22.8%              -5.5% 
Gartner                                      22.6%              -9.3% 
Eli Lilly                                    22.5%              31.9% 
Regeneron Pharmaceuticals                    22.4%              20.2% 
FactSet Research Systems                     22.1%              13.6% 
Cboe Global Markets                          21.9%              33.7% 
                                                      Source: FactSet 

October's worst S&P 500 performers

These 20 components of the S&P 500 fell the most for October:

 
Company                         October price change  2026 price change 
Intel                                         -45.3%              78.2% 
Reddit                                        -35.6%             -60.1% 
Sandisk                                       -33.9%             384.8% 
Teradyne                                      -31.6%              41.7% 
Seagate Technology Holdings                   -30.1%             134.1% 
Twilio                                        -29.9%              44.1% 
Lam Research                                  -27.2%              39.7% 
Coherent                                      -26.9%              14.0% 
Bloom Energy                                  -26.6%             133.8% 
Marvell Technology                            -25.7%             131.1% 
Comfort Systems USA                           -25.5%              32.1% 
Robinhood Markets                             -24.5%             -24.9% 
F5                                            -24.0%              32.5% 
Fortinet                                      -23.9%              71.4% 
Applied Materials                             -23.7%              51.8% 
Caterpillar                                   -23.2%               8.7% 
Skydance                                      -23.0%             -40.7% 
Coinbase Global                               -23.0%             -36.5% 
ServiceNow                                    -21.6%             -31.4% 
Flex                                          -21.4%              43.1% 
                                                        Source: FactSet 

Intel (INTC) was the S&P 500's worst performer during October, with its shares plunging 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

This content was created by MarketWatch, which is operated by Dow Jones & Co. MarketWatch is published independently from Dow Jones Newswires and The Wall Street Journal.

(END) Dow Jones Newswires

10-30-26 1652ET