Rihanna under Jay-Z management

New YorK: Grammy-winning pop singer has parted ways with manager Marc Jordan and is now being managed by Jay-Z’s Roc Nation Management. Rihanna told The Associated Press she’s “so excited to take this next step in my career.”The 22-year-old is also launching a new company called Rihanna Entertainment. She says it will “merge all of her businesses, including music, film, fragrance fashion and book ventures.”   Rihanna is to start new company Jay-Z signed Rihanna to Def Jam in 2005. The two won a Grammy in 2008 for the hit song “Umbrella.” Earlier this year, the pair picked up two Grammys for the rap song “Run This Town,” which also featured Kanye West.She has released four albums and plans to release her fifth CD, “Loud,” on November 16.