ATI vs MLI: How ATI Inc. and Mueller Industries Compare (2026)

Same yardstick, side by side (as of July 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: MLI 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. ATI and MLI 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 ATI and MLI 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.

ATI Inc. (ATI), formerly Allegheny Technologies, is a specialty materials and components producer focused on high-performance metals for demanding applications. Its core markets are aerospace and defense, where ATI supplies titanium, nickel-based superalloys, and other advanced alloys used in jet engines, airframes, and defense systems that must withstand extreme heat, stress, and corrosion. The company also serves medical, energy, electronics, and specialty industrial markets. ATI operates through two segments: High Performance Materials and Components (jet engine parts, forgings, and advanced alloys) and Advanced Alloys and Solutions (specialty rolled products and materials). The company has deliberately repositioned over the past several years away from lower-margin commodity stainless toward higher-value, harder-to-make aerospace and defense materials where it has technical differentiation and long qualification cycles that lock in customer relationships. Founded through the combination of specialty metals businesses and headquartered in Dallas, Texas, ATI is a cyclical industrial materials company whose results are tied closely to commercial aerospace production rates and defense spending.

Full ATI guide

Mueller Industries, headquartered in Collierville, Tennessee, is an industrial holding company that manufactures copper, brass, aluminum, and plastic products sold into plumbing, HVAC, refrigeration, oil and gas, medical, aerospace, and automotive end markets. The company operates through three reportable segments: Piping Systems (the largest, generating approximately 65-67% of revenue from copper tubes, fittings, line sets, valves, and related products sold to plumbing wholesalers, building material retailers, and OEMs), Industrial Metals (brass rod, copper bar, wire, and impact extrusions), and Climate (components for temperature-control systems, including twisted tubes, coaxial heat exchangers, and refrigeration valves). Manufacturing and distribution operations span North America, the United Kingdom, Canada, Asia, and the Middle East, with joint ventures in South Korea and Bahrain. The company traces its operational roots to 1917 and is listed on the NYSE under the ticker MLI. Gregory L. Christopher serves as Chairman and CEO, and under his leadership the company has executed a disciplined acquisition strategy, including Nehring Electrical Works and Elkhart Products in 2024, and Bison Metals Technologies in March 2026, all aimed at expanding nonferrous manufacturing capacity. MLI completed a 2-for-1 stock split effective July 1, 2026. The shareholder base is primarily institutional, with no single controlling shareholder.

Full MLI guide

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

• ATI drivers: Commercial aerospace recovery and ramp; Mix shift to high-value materials.
• MLI drivers: Structural demand from HVAC and electrification; Tariff-driven onshoring of copper manufacturing.

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: ATI is cyclical and concentrated in aerospace, so any slowdown in commercial aircraft production (for example, Boeing supply-chain or quality problems, or an air-travel downturn) hits demand directly. For MLI, mueller's revenue and margins are sensitive to U.S.

Growth-minded investors who believe the theme has years to run tend to accept the richer multiple for more upside; value-minded investors lean toward the cheaper forward earnings and steadier profile. Pick ATI if you believe its drivers more; MLI 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 ATI and MLI guides.

ATI. ATI trades as a cyclical aerospace and defense materials supplier, with its multiple expanding when commercial aircraft build rates and defense demand are strong. The repositioning toward higher-value alloys has improved margins and earnings quality, but the valuation still reflects sensitivity to the aerospace cycle and raw-material and capacity-ramp risks rather than steady-state stability.

MLI. MLI's trailing P/E of approximately 17x sits well below the U.S. Machinery sector average and its direct peer group, which has historically traded at 25-33x, suggesting the market applies a discount that may reflect cyclicality concerns around copper pricing and construction exposure. The 29% gross margin is materially above the company's own 10-year historical average and above the level that many analysts consider fully sustainable into a normalized cycle. The near-zero-debt balance sheet and approximately $1.4 billion in cash give the company exceptional financial flexibility and downside cushion that is unusual among comparably sized industrials.

Headline figures (approximate, early 2026): ATI shows revenue (ttm) ~$4.5 billion, operating margin ~low-double-digit percent (improving with mix), net income (ttm) ~$350-450 million, p/e (ttm) ~20-25x (cyclical); MLI shows revenue (full year 2025) ~$4.18 billion, revenue (ttm, as of q1 2026) ~$4.37 billion, net income (full year 2025) ~$765 million, diluted eps (full year 2025) ~$6.86.

ATI and MLI 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 ATI and MLI exposure against your real portfolio. It is not an investment adviser.