NewMarket Corporation (NEU) Slides Amid Weakness in Petroleum Additives Segment

The Harbor Capital Advisors released its “Mid Cap Value Fund’s” Q4 2025 investor letter. A copy of the letter can be downloaded here. Harbor Mid Cap Value Fund, subadvised by LSV Asset Management, delivered solid outperformance in the fourth quarter of 2025, with the Institutional Class returning 4.07% versus 1.42% for the Russell Midcap Value Index, benefiting from strength in value stocks as the Russell Midcap Growth Index declined 3.7% during the period. U.S. equities broadly advanced, with the S&P 500 Index rising 2.7% in the quarter and 17.9% for the full year, while mid-caps lagged, with the Russell Midcap Index up just 0.2% in Q4. For 2025, the Fund gained 15.95% (Institutional Class), outperforming the benchmark’s 11.05% return. Attribution data show a total quarterly excess return of 2.82%, largely from selection effects, underscoring the manager’s quantitative value discipline focused on fundamental undervaluation, improving momentum, and risk control. Looking ahead, management noted that while AI-driven large-cap leadership has elevated valuations in certain segments, mid- and small-cap value stocks continue to trade at more attractive multiples, positioning the Fund to capitalize on opportunities within economically sensitive and cash-generative businesses. In addition, please check the Fund’s top five holdings to know its best picks in 2025.

In its fourth-quarter 2025 investor letter, Harbor Capital Advisors' Mid Cap Value Fund highlighted stocks like NewMarket Corporation (NYSE:NEU). NewMarket Corporation (NYSE:NEU) is a specialty chemicals company producing performance additives used in petroleum products and industrial applications. The one-month return of NewMarket Corporation (NYSE:NEU) was -7.20% while its shares traded between $510.07 and $875.97 over the last 52 weeks. On February 25, 2026, NewMarket Corporation (NYSE:NEU) stock closed at approximately $616.60 per share, with a market capitalization of about $5.79 billion.

Harbor Capital Advisors' Mid Cap Value Fund stated the following regarding NewMarket Corporation (NYSE:NEU)  in its Q4 2025 investor letter:

"While several Fund holdings struggled — including NewMarket Corporation (NYSE:NEU) in the Materials sector. Newmarket struggled with general weakness in the petroleum additives business, one of the larger portions of its revenue. We continue to hold the stock in the Fund."

NewMarket Corporation (NYSE:NEU) is not on our list of 30 Most Popular Stocks Among Hedge Funds. As per our database, 27 hedge fund portfolios held NewMarket Corporation (NYSE:NEU) at the end of the fourth quarter, which was 21 in the previous quarter. While we acknowledge the risk and potential of NewMarket Corporation (NYSE:NEU) as an investment, our conviction lies in the belief that some AI stocks hold greater promise for delivering higher returns and doing so within a shorter time frame. If you're looking for an extremely undervalued AI stock that also stands to benefit significantly from Trump-era tariffs and the onshoring trend, see our free report on the best short-term AI stock.

In another article, we covered NewMarket Corporation (NYSE:NEU) and shared the insights by The London Company, an investment management firm, regarding the company. In addition, please check out our hedge fund investor letters Q4 2025 page for more investor letters from hedge funds and other leading investors.

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Disclosure: None. This article is originally published at Insider Monkey.