ACM vs FER: 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: ACM 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. ACM and FER 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 ACM and FER 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.

AECOM is in the business of engineering expertise, not steel. The company plans, designs, engineers and manages infrastructure programs for governments and large corporations: highways and transit systems, water and wastewater treatment, airports and ports, environmental remediation, flood defenses, and increasingly the power and site work behind data centers. It reports in three segments, Americas (about $2.9 billion of quarterly revenue), International (about $890 million), and a small AECOM Capital investment arm, and employs roughly 51,000 people. Critically, AECOM exited self-perform construction years ago, so it no longer takes fixed-price building risk on its own balance sheet. What is left is a professional services business with very little capital intensity, which is why return on equity runs near 29% on only about $3.35 billion of debt against $1.04 billion of cash.

Full ACM guide

Ferrovial N.V. designs, builds, owns and operates transport infrastructure across four segments: Highways, Airports, Construction and Energy. Highways is the one that carries the company. It holds roughly 43% of Canada's 407 ETR, the electronically tolled express route across the Greater Toronto Area, plus controlling interests in the Dallas-Fort Worth Managed Lanes (NTE, LBJ and NTE 35W), I-77 in North Carolina and I-66 in Virginia. These are long-dated concessions with pricing power written into the contracts, which is what separates them from ordinary construction work. Construction, run through Ferrovial Construction, Budimex in Poland and Webber in the United States, builds both third-party projects and the group's own concessions. Airports is now much smaller after Ferrovial sold a 19.75% stake in Heathrow for roughly EUR 2.0 billion in December 2024, keeping about 5.25%; the remaining marquee asset is a 49% interest in the New Terminal One at JFK. Energy handles transmission and generation projects. The company moved its primary corporate seat to the Netherlands and added the Nasdaq listing in 2024, and the shares now sit in the Nasdaq-100.

Full FER guide

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

• ACM drivers: A record backlog that is growing faster than revenue; Margin expansion in an asset-light model.
• FER drivers: 407 ETR pricing and volume recovery; Texas Managed Lanes maturing into cash.

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: The cash flow problem is the live issue and it is not resolved: operating cash flow fell 98% in the fiscal second quarter of 2026 and free cash flow went negative, while significant claims recorded in contract assets and other non-current assets grew to roughly $680 million from about $400 million at the September 2025 fiscal year end. For FER, concession assets are finite: the 407 ETR agreement runs to 2098, but shorter US concessions eventually revert to the state, and terminal value assumptions do a lot of work in most FER valuation models.

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 ACM if you believe its drivers more; FER 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 ACM and FER guides.

ACM. The valuation reflects skepticism about cash conversion, not about the order book. At roughly 12 times forward earnings and about 9.9 times EV/EBITDA, AECOM prices below an engineering and consulting peer group closer to 13 times, despite carrying higher margins than the peer average, a gap management has explicitly flagged in its investor slides. Trailing GAAP metrics look less flattering (net income of about $506 million on $16.0 billion of revenue is a 3.2% margin, giving a trailing P/E near 19.5), which is why the forward and trailing multiples tell such different stories. Return on equity near 29% and a share count down roughly 20% since 2020 are what the forward multiple is capitalizing.

FER. The trailing P/E sits near 50x on 2026 consensus, which looks absurd against a builder and reasonable against a concession owner, because equity-accounted stakes such as 407 ETR contribute dividends rather than proportional earnings. Most sell-side work on FER therefore uses sum-of-the-parts: discount each concession's cash flows to the end of its licence, add the construction and energy businesses at a modest multiple, then subtract holding-company debt. Dividend yield is around 1.8%, part of it paid in scrip, so the cash component is smaller than the headline suggests.

Headline figures (approximate, August 2026): ACM shows revenue (ttm) ~$16.0 billion, with net service revenue near $1.95 billion a quarter, fiscal 2026 guidance ~$5.90 to $6.10 adjusted EPS, ~$1.275 to $1.305 billion adjusted EBITDA, ~$400 million free cash flow, total backlog ~$26.2 billion, a record, up ~8% year over year, adjusted ebitda margin ~16.5% in fiscal Q2 2026, with Americas segment margin at ~20.0%; FER shows revenue (ttm) ~$9.86B, market capitalisation ~$42.4B, h1 2026 revenue ~EUR 4.70B (reported in euros), +5.2% reported and ~+11.3% like-for-like, h1 2026 adjusted ebitda ~EUR 746M, +13.9%.

ACM and FER 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 ACM and FER exposure against your real portfolio. It is not an investment adviser.