The High Pay Centre think tank said chief executives in the FTSE 100 were paid an average of almost £4.3 million in 2012, equivalent to an hourly wage of well over £1000, compared with the country's average annual wage of £26,000.
Executive pay has increased by 74% over the past decade, while wages for ordinary workers have remained "flat", the study found.
Company bosses who returned to work on Monday after the festive break will have made more money in 2014 by mid-morning today than the annual salary of average workers, said the report.
High Pay Centre director Deborah Hargreaves said: "Fat cat Wednesday highlights how insensitive big company executives have become."When top bosses take home more in two-and-a-half days than the average worker earns in a year, there is clearly something wrong."