Pittsburgh-based Buchanan Ingersoll & Rooney is set to merge today with Tampa-based Fowler White Boggs, creating a 530-lawyer firm that would become one of the 100 largest in the country by headcount.

The combined firm will be known in Florida as Buchanan Ingersoll & Rooney/Fowler White Boggs for one year, then revert to the name Buchanan Ingersoll & Rooney. The firm will be based in Pittsburgh and led by Buchanan Ingersoll CEO John A. “Jack” Barbour. It will have 18 offices throughout the country, including six in Florida that will house more than 100 attorneys in the state.