Legit agent Val Day has exited WME for ICM after a dozen-year career with the tenpercentery that began when she joined William Morris in 1999.Day has a roster of clients made up of both well-established stage names and up-and-comers, with a list that ranges from Athol Fugard and the estate of Eugene O’Neill to scribes including Amy Herzog and Dan LeFranc and helmers David Cromer and Hal Brooks. Many of those clients are expected to follow her to ICM, although no arrangements are yet certain. Day’s client list also includes writers Adam Bock and Jordan Harrison, writer-performer Nilaja Sun (“No Child …”), lyricist Chad Beguelin, composer Gabe Kahane and directors Trip Cullman, Gordon Edelstein, Anne Kauffman and Simon Phillips. While at William Morris and WME, Day acquired a rep for shepherding playwrights into crossover careers that also included TV and film work. Day officially starts her gig at ICM on Monday.