CENX vs RIO: Which Is the Better Buy in 2026?

Same yardstick, side by side (as of August 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: CENX 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. CENX and RIO 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 CENX and RIO 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.

Century Aluminum smelts primary aluminium and sells it as ingot, billet and other value-added shapes. Its US footprint centres on Sebree in Kentucky and Mt. Holly in South Carolina; Grundartangi in Iceland supplies the European market on low-carbon hydro and geothermal power; a carbon anode plant in the Netherlands feeds the smelters; and a majority stake in Jamalco covers bauxite mining and alumina refining in Jamaica, giving the group partial control of its own raw material. Roughly 2,906 people work across those sites. Chicago is the corporate base, and Glencore, a commodity trading house and long-time commercial partner, holds close to ~30% of the shares.

Full CENX guide

Rio Tinto is a global mining group that digs, processes, and ships the raw materials behind steel, power grids, and batteries. Iron ore from its Pilbara operations in Western Australia is still the profit engine, generating the majority of earnings, while the company also produces aluminum and bauxite, copper (including from the Oyu Tolgoi mine in Mongolia), and, after its 2025 acquisition of Arcadium, lithium. Its two marquee growth projects are the giant Simandou iron ore mine in Guinea, which made its first shipment in late 2025, and a lithium business it aims to scale toward 200,000 tonnes of lithium carbonate equivalent by 2028. RIO shares are American Depositary Receipts representing the London-listed Rio Tinto plc, so U.S. investors get the same underlying economics with dollar-denominated trading.

Full RIO guide

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

• CENX drivers: The Midwest premium and Section 232; Restarted capacity arriving into a strong price.
• RIO drivers: Iron ore scale plus Simandou; Copper growth for electrification.

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: Aluminium is a commodity and Century's earnings track its price with almost no cushion, which is why the shares carry a beta near ~2.0 and why full-year 2025 net income of ~$41.8M sat alongside trailing net income near ~$600M a year later. For RIO, rio's fortunes are tightly linked to iron ore prices, which hinge on Chinese steel demand and property construction, so a slowdown there hits earnings and the dividend directly.

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 CENX if you believe its drivers more; RIO 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 CENX and RIO guides.

CENX. Trailing multiples look undemanding at roughly ~8.5x earnings and about ~1.9x sales, and forward estimates screen near ~3x, but a low-single-digit forward multiple on a smelter usually says the market doubts the earnings are durable rather than that the shares are cheap. Second quarter revenue of ~$752M came in under consensus near ~$819M while adjusted EPS of ~$2.46 beat an estimate of ~$2.35, a split that tells you the beat came from price and mix rather than volume. Anything built off a peak Midwest premium is worth re-checking against the premium itself before it is treated as a run rate.

RIO. Revenue and EBITDA both grew in 2025, but reported profit slipped and net debt roughly tripled after the Arcadium lithium acquisition. Shares traded around the low-to-mid $90s at mid-2026 on a trailing P/E of roughly 15, a discount that reflects commodity-cycle risk. The full-year dividend of about $6.5 billion at a roughly 60% payout keeps the yield near 4%.

Headline figures (approximate, August 2026): CENX shows revenue (ttm) ~$2.67B, net income (ttm) ~$600M, eps (ttm) ~$5.79 to ~$6.02, market cap ~$5.14B; RIO shows revenue (2025) ~$57.6B, underlying ebitda (2025) ~$25.4B, underlying earnings (2025) ~$10.9B, net debt ~$14.4B.

CENX and RIO 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 CENX and RIO exposure against your real portfolio. It is not an investment adviser.