ACM vs WLK Comparison

Aecom is one of the largest global providers of advisory, design, and engineering services. It serves a broad spectrum of end markets, including water, transportation, and environment. Based in Dallas, Aecom employs 51,000 people. The company generated $16.1 billion in sales in fiscal 2025.

Westlake is a forward-integrated commodity chemicals firm based in Houston. It began as a single low-density polyethylene plant and expanded its capabilities to include ethylene, vinyl chloride monomers, and polyvinyl chloride over the next two decades. The acquisition of Axiall in 2016 made it a North American leader in chlor-alkali and PVC. Today, Westlake has two defined segments: performance and essential materials, and housing and infrastructure products. The HIP segment began operating in 2022 following a series of acquisitions in the building products space. The firm aims to maximize the value of its chemical production by integrating with the HIP segment, realizing the higher margins of finished commercial goods.