Diamond Hill Capital, an investment management company, released its “Mid Strategy” fourth-quarter 2025 investor letter. A copy of the letter can be downloaded here. The fourth quarter posted another period of favorable gains for equity markets, with small and large cap positions being stronger performers, returning 2.19% and 2.41%. While the mid-cap range was a relative laggard, with the Russell Mid Cap Index returning 0.16%. The Strategy returned 3.65% (net) in Q4, compared to 0.16% return for the Russell Midcap Index. YTD, the strategy returned 13.47%, outperforming the 10.60% return for the Index. In 2025, AI-related spending remained a key driver in equity markets, though December saw a pause as investors became more cautious about AI developments and potential market bubbles. Given the elevated equity market valuations, the Strategy is well-positioned to withstand ongoing uncertainty. Please review the Strategy’s top five holdings to gain insights into their key selections for 2025.
In its fourth-quarter 2025 investor letter, Diamond Hill Mid Strategy highlighted Westlake Corporation (NYSE:WLK) as a new addition. Westlake Corporation (NYSE:WLK) is a manufacturer and supplier of performance and essential materials, as well as housing and infrastructure products. On March 19, 2026, Westlake Corporation (NYSE:WLK) stock closed at $111.23 per share. One-month return of Westlake Corporation (NYSE:WLK) was 17.83%, and its shares gained 10.25% over the past 52 weeks. Westlake Corporation (NYSE:WLK) has a market capitalization of $14.268 billion.
Diamond Hill Mid Strategy stated the following regarding Westlake Corporation (NYSE:WLK) in its fourth quarter 2025 investor letter:
“Westlake Corporation (NYSE:WLK), a low-cost chemicals producer and emerging supplier of building products, is managing supply-side headwinds in its commodity businesses by adjusting capacity. As the housing market recovers from a prolonged downturn in new construction, we believe both segments of the business should benefit over the long term.”
Westlake Corporation (NYSE:WLK) is not on our list of 40 Most Popular Stocks Among Hedge Funds Heading Into 2026. According to our database, 37 hedge fund portfolios held Westlake Corporation (NYSE:WLK) at the end of the fourth quarter, compared to 42 in the previous quarter. While we acknowledge the risk and potential of Westlake Corporation (NYSE:WLK) 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 are looking for an AI stock that is more promising than Westlake Corporation (NYSE:WLK) and that has 10,000% upside potential, check out our report about this cheapest AI stock.
In another article, we covered Westlake Corporation (NYSE:WLK) and shared a list of best dividend aristocrat stocks to invest in. In addition, please check out our hedge fund investor letters Q4 2025 page for more investor letters from hedge funds and other leading investors.
READ NEXT: 33 Stocks That Should Double in 3 Years and 15 Stocks That Will Make You Rich in 10 Years.
Disclosure: None. This article is originally published at Insider Monkey.
