Freddie Mac’s refinance-loan purchase volume dramatically dropped 33 percent in July, from $50.9 billion to $34.1 billion, the company revealed this week, as rising mortgage rates choked off a healthy refi boom. Experts believe the surge in refinance mortgage lending ground to a halt after mortgage rates crept up over 5.00 percent. Freddie also indicated its purchases fell sharply, from $63.15...