Final answer:
The exact percentage of U.S. companies linking compensation to sustainability metrics in 2018 isn't provided, but the trend towards sustainable business practices has been growing, as seen in Walmart's and other companies' goals.
Step-by-step explanation:
In 2018, the percentage of U.S. companies that linked compensation to sustainability metrics is not explicitly provided in the referenced material. Companies across various sectors, as exemplified by Walmart and Inditex, have been increasingly integrating sustainability into their business strategies. Walmart, being the world's largest company by revenue, announced ambitious sustainability goals, including a plan to reduce its global emissions to zero by 2040. Such initiatives often include linking executive and employee compensation to the attainment of sustainable practices and goals.
While specific data points from 2018 are not readily available in the provided references, it is clear that the incorporation of sustainability metrics in compensation structures is growing as companies recognize the economic advantages and societal pressures to address environmental concerns. Organizations such as those in attendance at the COP24 and the signatories of the Fashion Industry Charter for Climate Action are moving towards practices that reduce environmental impact and promote sustainability.