ACM vs PSN: How AECOM and Parsons Corporation Compare (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.

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 PSN 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 PSN 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

Parsons Corporation is a technology-driven provider of services to the U.S. government and to owners of complex infrastructure. It reports in two segments: Federal Solutions, which delivers cybersecurity, missile defense, intelligence, space and ground systems, geospatial and signals intelligence, environmental remediation, and border and critical-infrastructure security, primarily to the Intelligence Community, the Departments of Defense, Energy, Homeland Security, and agencies like NASA and the FAA; and Critical Infrastructure, which provides program management, design and engineering, and owner's-representative support for large physical and digital projects worldwide. Federal Solutions has historically contributed a bit over half of revenue and Critical Infrastructure the rest, so the company sits at the intersection of national-security spending and infrastructure investment rather than any single commercial end market.

Full PSN 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.
• PSN drivers: Backlog, book-to-bill, and new awards; Record margins and mix shift.

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 PSN, the most immediate risk is concentration: the wind-down of a single confidential contract is enough to turn organic growth negative, showing how much one program can move results.

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; PSN 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 PSN 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.

PSN. Figures are approximate and tied to the asOf date; verify live numbers before acting. The valuation reflects a company whose margins and backlog are at records while reported revenue is temporarily shrinking because of one contract, so the multiple is essentially a judgment about how quickly new awards convert into revenue. Analyst targets skew above the current price on the backlog and book-to-bill, but that view assumes the confidential-contract gap gets refilled on a reasonable timeline.

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%; PSN shows revenue (ttm) ~$6.3 billion (FY2025 was ~$6.4 billion; Q1 2026 ~$1.5 billion, down ~4% year over year), net income (fy2025) ~$241 million, q1 2026 eps ~$0.49 GAAP (adjusted ~$0.79, above consensus), adjusted ebitda margin (q1 2026) ~10.1% (a record).

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