Michael Bloomberg spent more than $1 billion (£813m) during 104 days of his presidential campaign, it has been revealed.
A Federal Election Commission filing from Monday, showed that the former mayor spent over $1 billion in less than four months.
Mr Bloomberg had a staff of more than 2,400 to help him in his presidential bid, according to ABC.
Another billionaire, Tom Steyer, worth approximately $1.6 billion (£1.3bn), also ran for the Democratic nomination, but only spent $340 million (£276.6m) on his campaign.
The former mayor of New York City began his campaign to be the 2020 Democratic nominee for president, in November, but dropped out in March.
Mr Bloomberg decided not to compete in the states of Iowa and New Hampshire and officially started competing for the nomination on Super Tuesday, where 14 states had primaries and American Samoa held their caucus.
He only won 55 delegates on the day, but did win the American Samoa Caucus.
The filing shows that he spent $176 million (£143m) in March alone, despite dropping out of the race on 4 March, the day after Super Tuesday.
Mr Bloomberg caused outrage among his staff last month, after he broke his promise to keep his campaign team employed until the November election.
Instead of keeping his staff on to campaign for the chosen Democratic nominee, Mr Bloomberg transferred $18 million (£14.6m) to the Democratic National Committee.
Some campaign organisers filed lawsuits against the former mayor and the Republican party argued his donation broke campaign finance rules.
Former vice president Joe Biden, who is the presumptive Democratic nominee, has yet to file his campaign finances for March.
