S&P 500 Gains and Losses Today: Index Falls as Port Workers Begin Strike

Key Takeaways

• The S&P 500 fell 0.9% on Tuesday, Oct. 1, 2024, amid concerns about the economic impact of a strike by workers at major port facilities.
• Humana shares dropped after the insurer unveiled its Medicare Advantage plans for next year.
• Shares of oil and gas companies and defense firms moved higher as tensions intensified in the Middle East.

Major U.S. equities indexes moved lower as dockworkers went on strike at port facilities on the East and Gulf coasts. The labor action by members of the International Longshoremen's Association (ILA) could unsettle supply chains and cause a ripple of impacts throughout the economy, including a potential increase in inflation.

The S&P 500 fell 0.9% on Tuesday, retreating from Monday's record close. The Dow slipped 0.4%, while the Nasdaq dropped 1.5%, pressured by the tech sector.

Amentum Holdings (AMTM) shares plunged 20.2%, reversing similarly sized gains posted in the previous session as the government services firm debuted as a publicly traded company and became the newest member of the S&P 500. The company brings together an existing engineering and technology provider with two government-related divisions spun off from Jacobs Solutions (J).

The rise and fall of Amentum shares corresponds with the pattern of stocks receiving a temporary bump upon their addition to the S&P 500 as funds that track the index buy the newly added constituent. After notching the top performance in the benchmark index on Monday, Amentum was the weakest stock in the S&P 500 on Tuesday.

Shares of Humana (HUM) dropped 11.8% after the health insurer announced its Medicare Advantage and Medicare Prescription Drug Plan offerings for 2025. The company announced new benefits including a new pair of glasses every year for all plans with vision coverage and plans with comprehensive dental coverage. Although Humana has seen some improvement in its Medicare business, challenges related to Medicare reimbursement rates contributed to the firm's decision to withdraw its full-year profit guidance in April.

According to regulatory filings, Dell Technologies (DELL) founder and CEO Michael Dell sold a $1.2 billion stake in the tech hardware and services provider. Significant selling by company insiders can cause investors to become less optimistic about a stock's expected trajectory, and Dell shares sank 4.5% on Tuesday. Dell is another recent addition to the S&P 500.

Tuesday's top performance in the S&P 500 belonged to shares of Paychex (PAYX), which jumped 4.9% after the payroll services provider reported better-than-expected sales and profits for its fiscal first quarter. The firm said expansion of its client base, strong cost controls, and new artificial intelligence (AI) products contributed to the strong results.

Crude oil futures prices increased around 3.7% as growing tensions in the Middle East raised concerns about global energy supplies. The uptick in prices provided a boost to numerous oil and gas stocks. Shares of APA Corp. (APA) added 4.9%, while shares of ConocoPhillips (COP) and Marathon Oil (MRO) were up 3.9% and 3.8%, respectively.

The rising geopolitical concerns also helped lift defense and weapons stocks. Lockheed Martin (LMT) shares added 3.6%, while shares of other companies in the defense industry also advanced.

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