To create the top 250 I sourced companies from a variety of lists:
Next I checked each company against myvisajobs.com, the publicly available database of companies who have submitted petitions for H1B. If a company had a history of sponsoring they were included in the Top 250. However if the data indicated they didn't hire international candidates frequently they are not on this list. For example, Unilever only submitted 3 petitions for H1B sponsorship in 2016 for the entire company. This indicates that they rarely sponsor for H1B. They likely only make a rare exception for a candidate, probably an experienced hire. This is not helpful for new grads. So Unilever and those like it are not on this list. I made exceptions to this rule for smaller companies (financial management companies, hedge funds, startups, etc), or for companies/jobs in industries that are underrepresented in this list (i.e. retail, think tanks, companies that employ economists or fashion designers).
I also included companies that hire the most international students according to occupational category. Companies that hired software developers, engineers of all types, analysts, data scientists, consultants, financial analysts and managers, marketing managers, make up most of this list. Excluded from this list are most outsourcing and IT staffing companies.
The result is that every company on this list has a history of sponsoring international candidates.
However, even though a company has a history of hiring international candidates it doesn't mean they will always hire them. Data from publicly available sources show that the companies on this list have a history of hiring international candidates for several years. It is the best predictor that they will continue to hire international candidates for the near future. However:
A company's willingness to hire international students is always subject to change.