Homeowners who refinanced a $200,000 mortgage in the first quarter of 2015 have already saved thousands of dollars, according to Freddie Mac. Unfortunately, many other homeowners have not taken advantage of the recent low interest rates — and their inaction has come at a big cost: A study published in Journal of Financial Economics revealed that homeowners missed out on $5.4 billion in savings because 20% of homeowners who would have benefited from refinancing did not pursue the option .