Pop star Taylor Swift and British soul singer Sam Smith were the leaders among the 2015 Billboard Awards finalists with four nominations each after five top categories were announced on Tuesday. Swift, 25, and Smith, 22, earned nods for top artist, as well as for best female and male artist. Swift's "1989" will compete with Smith's "In the Lonely Hour" for the top album prize. Rapper Ludacris, who will host the awards with supermodel Chrissy Teigen, announced the nominations in the five categories on ABC's early news show, "Good Morning America," with Pete Wentz of the rock band Fall Out Boy.??