A billionaire, who had been mayor of the largest city in the United States as an Independent candidate, has donated $2.5 million to a Democratic Super PAC.

Former Mayor Michael Bloomberg, I-N.Y., and the billionaire majority owner of Bloomberg LLP, a financial news service, has donated $2.5 million to the Senate Majority PAC, a Democratic-oriented super PAC, that does not have contributions limits. The donation was disclosed to Politico by Howard Wolfson, a close aide to Bloomberg.

The Senate Majority PAC has raised just over $3 million in the first six and half months of 2013, and spent almost $1.4 million on independent expenditures. They will report their financial activity for the rest of 2013 before January 31, 2014. Financial activity in early 2014 will probably be reported in the April.