On the heels of his announcement that he plans to close the Department of Education, President Donald Trump said Friday that his administration will move the federal student-loan portfolio to the Small Business Administration in an effort to manage the program better. But experts warn that any move — should it withstand legal challenges — would likely create headaches for borrowers. “I’ve decided that the SBA, the Small Business Administration, headed by Kelly Loeffler, who is a terrific person, will handle all of the student-loan portfolio,” Trump said Friday. “We have a portfolio that’s very large, lots of loans, tens...