AOS vs PNR: Which Is the Better Buy in 2026?

Same yardstick, side by side (as of September 2026). Valuation lined up like this is most meaningful for two names in the same corner of the market, which these are. Figures are approximate; verify before investing.

Reading it: PNR is the cheaper of the two on forward earnings, but cheaper is not the same as better. Pair the valuation with growth (how far the forward P/E sits below the trailing P/E) and risk (beta) before you decide.

The metrics above tell you which is the marginally better business. The bigger risk for most people is not picking the slightly worse stock, it is over-concentrating. AOS and PNR share themes, so owning both, or adding either to what you already hold, can quietly push a large share of your portfolio into one bet.

This is the part a generic comparison page cannot answer, because it depends on what you own. Connect your brokerage and Walnut shows your real, combined AOS and PNR exposure, flags overlap with your existing positions, and tells you if adding one would tip you past a concentration you are comfortable with, read-only by default, with your login staying at your broker. Walnut is not an investment adviser.

A. O. Smith is a Milwaukee-based manufacturer of water heating and water treatment products. Its core business is residential and commercial water heaters and boilers, where it is one of the top players in North America alongside Rheem and Bradford White, plus a faster-growing line of water treatment and filtration products. The North America segment drives roughly 78 percent of sales, and the Rest of World segment (around 22 percent, a majority in China, with a rising India contribution via the Pureit brand) is the international lever. Much of North American demand is non-discretionary replacement of failed units, which gives the revenue base a defensive, recurring quality.

Full AOS guide

Pentair plc is a roughly $4 billion revenue water treatment and flow company that most consumers know through its Pool segment, which makes pumps, filters, heaters, automation, and sanitization gear for residential and commercial swimming pools. Beyond pools, the Water Solutions segment sells residential and commercial water treatment (softeners, filtration, and quality systems) plus, after a January 2026 reorganization, the residential and irrigation flow business, while the Flow segment covers industrial, agricultural, and municipal pumps and fluid-handling equipment. As of July 2026 Pentair carries a market capitalization near $12 billion and trades around the high $70s, well off its 52-week highs above $110.

Full PNR guide

Both fit overlapping themes, but they are not interchangeable. The useful comparison is which set of drivers and risks you want exposure to.

• AOS drivers: North American replacement demand; Water treatment and India (Pureit).
• PNR drivers: Pool as the profit and growth engine; Transformation and margin expansion.

A faster-growing, richer-valued name usually swings harder, so it suits a longer horizon and a higher tolerance for volatility; a steadier, more cash-generative business suits a more conservative or income-minded investor. The honest test is which set of risks you could hold through a drawdown: China remains the biggest swing risk, with Rest of World sales pressured by a double-digit China decline that can mask North American strength. For PNR, pool and water-treatment demand is cyclical and sensitive to housing activity, discretionary spending, and interest rates, and new-pool construction has been soft, which pressures volumes.

Pick AOS if you believe its drivers more; PNR if you believe its. Many investors hold both, but since they share themes, that is a concentrated bet, not diversification. Decide deliberately and check overlap. For the full detail, see the AOS and PNR guides.

AOS. AOS trades like a quality industrial, with a P/E broadly in the mid-to-high teens depending on the price and earnings basis used. Q1 2026 revenue of about $946 million fell roughly 2 percent year over year and EPS of $0.85 missed, driven by China weakness and a plant disruption, which led management to lower the full-year outlook. The dividend has been raised for more than 30 straight years at a payout ratio in the mid-30s percent.

PNR. Pentair trades around the high $70s in July 2026, well below its 52-week high above $110, at roughly 19 times earnings with a dividend yield near 1.4 percent. Revenue has grown only modestly (Q1 2026 sales up about 3 percent to roughly $1.04 billion), so the earnings story is powered by margin expansion and price rather than volume. The valuation reflects a quality industrial compounder whose growth has cooled, leaving investors to judge whether margins and pool demand hold up.

Headline figures (approximate, July 2026): AOS shows revenue (ttm) ~$3.8B, net income (2025) ~$525M, diluted eps (2025, record) ~$3.85, 2026 adj. eps guidance ~$3.70-$4.00; PNR shows revenue (ttm) ~$4.1B, q1 2026 sales ~$1.04B (up ~3%), adjusted eps (2025) ~$4.86, 2026 adjusted eps guidance ~$5.30 to $5.40.

AOS and PNR are related but distinct: same themes, different businesses and risks. Neither wins in the abstract; the right pick is whichever thesis you actually believe, sized so you are not over-concentrated in one theme. Walnut can show your combined AOS and PNR exposure against your real portfolio. It is not an investment adviser.