"The permit was the resolution, " Mr. Covar said, and no fine was issued.

WSJ: About 14 Killed in West, Texas, Fertilizer Plant Blast

One way is to use CoVAR (Conditional VAR), a measure that aims to capture spillover effects in troubled markets, such as losses due to the distress of others.

ECONOMIST: The uses and abuses of mathematical models

Zak Covar, executive director of the environmental-quality commission, said the fertilizer storage and blending facility had existed since 1962, before permits were required, and was allowed to remain on the site.

WSJ: Fertilizer-Storage Risk Is Often Overlooked