Initially , the Horizon League chose not to expand to replace Butler , as the school still had nine full-time members , including Valparaiso University within the state of Indiana where both Butler and headquarters of the Horizon League are located . However , the split of the original Big East Conference , leading to the formation of the current Big East , had further fallout involving the Horizon League . Loyola University Chicago , the last remaining charter member from the Horizon League 's founding in 1979 , announced in April 2013 that it would leave the Horizon effective July 1 to join the Missouri Valley Conference , which itself had lost Creighton to the reconfigured Big East . Within a month , the Horizon had announced that Loyola would immediately be replaced by Oakland University , formerly of The Summit League . The addition of Oakland brought in a natural rival to the University of Detroit Mercy and kept the Horizon League at nine full-time members . Butler 's spot in the Horizon League would eventually be filled in 2015 with the addition of Northern Kentucky University , which also served to expand the conference into the Upland South
original Big East Conference
Big East Conference (1979–2013)
2010–2014 NCAA conference realignment