According to the government website:
Severe financial loss to a company or person, provided that the need for urgent action is not the result of the petitioner’s or applicant’s failure to:
File the benefit request or the expedite request in a reasonable time frame, or
Respond to any requests for additional evidence in a reasonably timely manner;
Urgent humanitarian reasons;
Compelling U.S. government interests (such as urgent cases for the Department of Defense or DHS, or other public safety or national security interests); or
Clear USCIS error.
You can read more here https://www.uscis.gov/forms/how-make-expedite-request