Many of 2026's hottest stocks have seen dramatic comedowns this week

By Philip van Doorn

Many of the best-performing stocks of 2026 fell this week, while this year's biggest losers also changed course

These are two of the best-performing stocks of 2026, which reversed course to show significant declines this week.

This week's action in the stock market has reflected investors' concerns about higher long-term interest rates and a simmering of the AI infrastructure trade. But in an interesting twist, it has also featured a change in sentiment for this year's best and worst performers.

The bond market provided its own warning on what may be overexuberance for an industry group riding the artificial-intelligence build-out - neoclouds, which are pure-play providers of cloud services. These companies have seen revenue soar, but some investors are concerned that the inevitable growth in supply will lead to declining sales and fierce price competition for what will turn out to be a commoditized service.

CoreWeave's (CRWV) stock was down 15.1% for the week through Thursday, but a more painful sign came from the bond market. The company's bonds issued in April with a 9.75% coupon were trading for 81 cents on the dollar on Wednesday.

Despite some alarming headlines, the S&P 500 SPX was showing a modest 0.9% gain for the week through Thursday, excluding dividends, with all but three sectors rising. Among the S&P 500, 357 stocks were up for the week.

The worst-performing sector was information technology, which fell 3.9% for the week through Thursday, after rising 29.9% for 2026 through Friday, Oct. 9. And the iShares Semiconductor ETF SOXX, which holds stocks of 30 chip makers and related companies, was down 8% for the week through Thursday.

2026 winners become this week's losers

We sorted the S&P 500 by stock-price changes for 2026 through Oct. 9, to illustrate investors' change in attitude this week. It turns out that among the 20 best performers through last week, all but three were down this week, and 11 of the stocks were down double digits.

 
Company                         2026 price change through Oct. 9  Price change from Oct. 9 through Oct. 15  Forward P/E  Forward P/E at end of 2025 
Moderna                                                   663.0%                                      5.1%          N/A                         N/A 
Sandisk                                                   566.4%                                    -11.8%          6.1                        13.6 
Dell Technologies                                         365.6%                                    -19.2%         16.1                        11.1 
Micron Technology                                         260.5%                                     -9.5%          5.2                         8.3 
Marvell Technology                                        223.9%                                    -12.4%         37.8                        24.1 
Bloom Energy                                              222.8%                                    -15.8%         51.9                        79.3 
Hewlett Packard Enterprise                                205.8%                                    -20.2%         12.6                         9.9 
Lumentum Holdings                                         199.3%                                    -21.2%         34.0                        52.0 
Seagate Technology Holdings                               184.3%                                    -11.8%         16.0                        20.7 
Advanced Micro Devices                                    183.9%                                     -7.5%         39.3                        32.7 
Intel                                                     183.7%                                     -8.9%         46.8                        61.9 
Marathon Petroleum                                        179.8%                                      4.8%          8.4                        11.5 
Valero Energy                                             166.4%                                      2.4%          9.3                        12.8 
Fortinet                                                  145.2%                                     -6.6%         49.0                        27.1 
CrowdStrike Holdings                                      134.7%                                    -11.1%        163.0                        99.5 
Western Digital                                           130.6%                                    -10.3%         14.7                        20.1 
Everpure                                                  130.5%                                    -13.7%         35.4                        29.7 
Palo Alto Networks                                        127.4%                                    -11.6%         85.5                        45.3 
NetApp                                                    121.4%                                     -9.5%         20.4                        12.8 
Datadog                                                   115.6%                                     -9.2%         92.6                        58.1 
                                                                                                                                    Source: FactSet 

Moderna (MRNA) was a standout exception on the above list, with the stock adding another 5.1% for a year-to-date gain of 663% through Thursday.

From Sept. 30: Citi tells investors it's time to sell Moderna after 600%-plus stock gains

In addition to the price changes, the table includes forward price-to-earnings ratios based on Thursday's closing prices and consensus earnings-per-share estimates among analysts polled by FactSet. The rightmost column shows forward P/E ratios at the end of last year. For the full S&P 500, the forward P/E has declined to 19 from 22.2 at the end of 2025, because weighted rolling 12-month EPS estimates for the index have increased 31.9% as the index's price has risen 13.1%.

The trend for declining P/E might be more notable in the next list, below, of the year's biggest losers among the S&P 500. But on this first list, Micron (MU) and Sandisk (SNDK) are among the tech stocks with particularly low P/E, and two of the energy names - Marathon Petroleum (MPC) and Valero Energy (VLO) - have single-digit P/E.

Related tech coverage:

-- Micron's ridiculously cheap stock could triple from here, according to this analyst's math

-- Don't ditch tech stocks just yet. Make these moves to take advantage of the latest AI reset.

-- Nvidia and other chip stocks face renewed pressure as AI fears swell

Downtrodden stocks reversing this week

Here are the 20 worst performers for the S&P 500 through last Friday, Oct. 9. All are up this week, with the exception of Tractor Supply (TSCO).

 
Company                                    2026 price change through Oct. 9  Price change from Oct. 9 through Oct. 15  Forward P/E  Forward P/E at end of 2025 
Fair Isaac                                                           -60.5%                                     15.3%         15.6                        39.9 
AppLovin                                                             -58.9%                                      0.8%         14.6                        45.8 
CoStar Group                                                         -55.9%                                      7.9%         19.5                        48.7 
Boston Scientific                                                    -55.2%                                      3.3%         13.1                        27.4 
Lululemon Athletica                                                  -54.5%                                      4.9%         11.3                        16.5 
Intuit                                                               -54.3%                                      9.1%         14.0                        27.0 
Insulet                                                              -52.4%                                      2.6%         18.6                        45.5 
Charter Communications                                               -50.5%                                      6.4%          2.6                         4.9 
Pentair                                                              -49.6%                                      1.9%         10.5                        19.3 
Fidelity National Information Services                               -48.8%                                      6.1%          5.5                        10.5 
Rollins                                                              -46.7%                                      6.0%         27.0                        47.6 
Nike                                                                 -45.5%                                      7.0%         27.4                        31.2 
Las Vegas Sands                                                      -44.4%                                      5.9%         11.3                        20.3 
Zoetis                                                               -40.5%                                      4.8%         12.3                        18.5 
Wynn Resorts                                                         -37.5%                                      2.4%         16.5                        21.0 
CRH                                                                  -34.7%                                      1.0%         13.2                        20.4 
McCormick                                                            -34.2%                                      2.0%         14.3                        21.1 
Cooper                                                               -33.7%                                      5.6%         12.2                        17.8 
Equifax                                                              -32.8%                                     10.6%         16.7                        24.7 

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10-16-26 1209ET