NEW YORK ( TheStreet) -- Citigroup ( C) said Monday that its Citi Holdings division of noncore assets now represents less than 20% of its balance sheet, after having closed the sale of $31 billion worth of student-loan assets. In two transactions, the New York-based banking giant sold $27 billion worth of loans to SLM Corp. ( DFS), the holding company of Sallie Mae, and another $4.2 billion worth of assets to Discover Financial Services ( DFS) in a $600 million deal. The assets were part of Citi's Student Loan Corp. subsidiary. Citi also retained $8.7 billion worth of the student-loan book, transferring the assets from its noncore Citi Holdings portfolio into its Citibank division. As of Dec. 31, it had whittled down Citi Holdings to less than 20% of Citi's balance sheet, the company said, down from nearly 30% a year earlier. In recent trading Citi shares were up 2% At $4.82, Discover was up 1.1% at $18.73 and SLM was up 1.2% at $12.74. -- Written by Lauren Tara LaCapra in New York. >To contact the writer of this article, click here: Lauren Tara LaCapra. >To follow the writer on Twitter, go to http://twitter.com/laurenlacapra. >To submit a news tip, send an email to: email@example.com.