A brief September surge in mortgage refinancing activity appears to be wrapping up as mortgage rates climb. After several weeks of gains, refinancing applications dropped 21% through Friday compared to a week earlier, according to Mortgage Bankers Association data. Mortgage rates reached a three-week high last week, averaging around 6.46%, according to the trade group. “After the burst in refinancing activity over the past month, this reversal in mortgage rates led to a sizeable drop in refinance applica ...