Student Loan ( STU) shares slid Friday after the Citigroup ( C - Get Report) unit posted a weaker first-quarter profit. For its quarter ended March 31, the Stamford, Conn., lender earned $66 million, or $3.31 a share, down from the year-ago $73 million, or $3.64 a share. Revenue fell 11% from a year ago to $127.5 million, on the back of lower interest income and other fees. Latest-quarter net interest income fell 2% to $129 million, while first-quarter return on equity dropped to 23% from 30% a year earlier. On Friday, Student Loan dropped $5.57 to $214.30.