Mortgage credit availability rebounded sharply in July, reaching its highest level in four years after falling to a six-month low in June, the Mortgage Bankers Association reported Tuesday. Non-qualifying mortgage (non-QM) loans do not conform to so-called “agency” guidelines for loans eligible for purchase by Fannie Mae, Freddie Mac and Ginnie Mae. Amid persistent affordability barriers, greater flexibility in non-QM underwriting has supported steady growth in non-QM origination share in recent quarters. The index measures consumer access to mortgage financing, based on factors including credit score and loan-to-value ratios relative to the variety of loan programs and structures actively offered by lenders. Within the conventional index, credit availability for jumbo mortgages — loans exceeding conforming loan limits — rose 4.2% in July, compared to a 0.2% decline in the conforming component index.