Stephen Pagliuca (D), a managing partner and executive committee member of the Boston Celtics, will announce his campaign for Senate today, according to several Boston news sources. He will reportedly make his announcement at the Celtics basketball arena this afternoon.

The Celtics co-owner is also a managing director at Bain Capital, which means he is in a position to put considerable personal resources into the race.

He joins several other Democrats who are running in the Dec. 8 special election primary, including state Attorney General Martha Coakley. Additionally, Rep. Mike Capuano (D) and City Year Co-Founder Alan Khazei (D) have taken out the appropriate paperwork to run for the seat of the late Sen. Edward Kennedy (D). Capuano is expected to formally announce his campaign Friday. Rep. Stephen Lynch (D) announced earlier this week that he would not run, although he had been expected to do so.

State Sen. Scott Brown is running for the GOP nomination, but the winner of the Democratic primary contest is expected to win the general election on Jan. 19.