Advanced Drainage Systems (WMS) Soared as Multiple Tailwinds Align

Brown Brothers Harriman, an investment management company, released its Q3 2025 investor letter for the BBH Select Series – Mid Cap Fund. A copy of the same can be downloaded here. In the quarter, the fund decreased by -0.9% on a total return basis compared to the Russell Midcap Index’s 5.3% return. The Fund has decreased by a total return of -1.8%, YTD, compared to 10.4% for the Index. The third quarter experienced a boost in the low-quality rally that started late last year and gained momentum throughout 2025. For more information on the fund’s best picks in 2025, please check its top five holdings.

In its third-quarter 2025 investor letter, BBH Select Series – Mid Cap Fund highlighted stocks such as Advanced Drainage Systems, Inc. (NYSE:WMS). Advanced Drainage Systems, Inc. (NYSE:WMS) is a manufacturer and marketer of thermoplastic corrugated pipes and related water management products. The one-month return of Advanced Drainage Systems, Inc. (NYSE:WMS) was -2.42%, and its shares gained 13.05% of their value over the last 52 weeks. On December 09, 2025, Advanced Drainage Systems, Inc. (NYSE:WMS) stock closed at $144.80 per share, with a market capitalization of $11.26 billion.

BBH Select Series – Mid Cap Fund stated the following regarding Advanced Drainage Systems, Inc. (NYSE:WMS) in its third quarter 2025 investor letter:

“For the quarter, the Fund’s largest positive contributors were Arista Networks Inc. (Arista) and Advanced Drainage Systems, Inc. (NYSE:WMS).

Advanced Drainage returned 20.9% during the quarter, ending with a weight of 4.0%. Advanced Drainage is the leading manufacturer of thermoplastic pipe and allied products for stormwater and wastewater management applications. Despite difficult end markets, Advance Drainage has executed well and delivered better than expected sales and earnings and reiterated fiscal 2026 guidance. Although organic growth was down slightly in the quarter due to wet weather and continued interest rate headwinds, the company outgrew most of its end markets. Aside from infrastructure, the company’s sales grew in all end markets. Its higher margin leach field, stormwater, and wastewater categories grew faster than its core pipe products. For example, Advanced Drainage saw double-digit organic growth in sales of on-site waste water tanks driven by material conversion to plastic. Demand was also supported by strength in the multifamily residential market, where the company saw double-digit growth of key products like retention/detention chambers, water quality products, and stormwater capture structures. Water quality remains a key growth area for the company and this category has grown at high-teens CAGR over the last three years.”

In another article, we covered Advanced Drainage Systems, Inc. (NYSE:WMS) and shared Madison Small Cap Fund’s views on the company. In addition, please check out our hedge fund investor letters Q3 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.