FAA CU's members include employees of the Federal Aviation Administration as well as residents of an eight county-area surrounding Oklahoma City.

Rasmussen said the credit union added two new loan originators in 2014 who were focused on getting out into the field to meet Realtors to bring them up to date on FAA CU's mortgage lending program.

The $393 million Fort Bragg Federal Credit Union in Fayetteville, N.C., has also seen a rise in lending activity after increasing the number of mortgage loans it portfolios according to asset liability management restrictions, according to David Elliott, president/CEO. Roughly 35% of the credit union's loan portfolio is in mortgages, he said.

"We tend to think in terms of buckets," Elliott explained. "We have a bucket for fixed rate 30-year, a bucket for fixed rate with shorter terms. When the bucket for fixed rate 30s is full, we stop putting those in portfolio and sell them instead."

Putting loans into portfolio gives the credit union more flexibility to meet members' mortgage needs, Elliot said.

"We don't specialize in them, but we do some jumbo loans too, when our members need them," he added.

In North Carolina, jumbo mortgage loans are defined as housing finance loans worth more than $417,000. Because of the threshold, they do not conform to secondary market rules.

According to NCUA data, Fort Bragg FCU closed 2014 with roughly $58.2 million in first mortgage loans originated, which was up from $54.4 million in 2013.

Lloyd Gill, president/CEO of the $415 million We Florida Financial Credit Union in Fort Lauderdale, Fla., has also seen an increase in adjustable rate mortgage loans held on its books.

"We are all, or almost all, ARMs in portfolio. Either 5/1 ARMs or 5/5 ARMs," Gill said, adding the credit union hasn't experienced any trouble convincing members to take the loans when they see the better interest rates for the shorter terms.

"We offer 2.95% on the ARMs for the first five years and they would reset after five," Gill said.

Members can refinance with We Florida Financial prior to that date for a $500 fee.

"We don't advertise it, but that is an option we offer," Gill said, noting that it is better to offer that deal than risk losing the loan to a refinance from another lender.

According to NCUA data, We Florida Financial closed 2014 having originated $57.3 million in mortgage loans, which was up from roughly $52.2 million in 2013.

We Florida Financial was previously known as City County Credit Union until a name change in October 2014.

Meanwhile, another sign that credit unions are holding onto more mortgages occurred in January when Arch Mortgage Insurance, the Walnut Creek, Calif.-based firm that purchased CMG Mortgage Insurance in Feb. 2013, announced it created a new company to insure only mortgage loans headed for financial institution portfolios.

Arch Mortgage Guaranty Co. will insure various types of prime, standard and non-standard mortgages, including jumbo, non-qualified mortgages and portfolio mortgages on an individual, bulk, or pool basis, according to Arch MI.

The company created the new firm with an eye toward helping credit unions become more competitive when they portfolio mortgage loans by offering more flexibility with the types of loans that are underwritten, according to David Gansberg, president/CEO of Arch MI.

"As a non-GSE insurer, Arch Mortgage Guaranty will still be insuring prime quality, full documentation loans on a primary and pool basis," Gansberg wrote in an email exchange with CU Times. "However, these will include loans such as jumbos that exceed Fannie Mae or Freddie Mac loan limits, along with certain non-QM loans, such as those with debt to income ratios that exceed 43% and short-term ARMs.

One more indicator that credit unions are holding onto to more mortgages is the increased pressure some lenders have faced as they try to work within the CFPB's rules on what is considered a qualified mortgage. If a financial institution has less than $2 billion in assets and originates 500 or fewer first mortgages per year, the loans it makes and holds in its portfolio can qualify as qualified mortgages.

For those loans, lenders need only to verify the borrowers' debt to income ratio, according to Michael Croal, senior director with the Phoenix-based research firm Cornerstone Advisors.

"We do see some interest in portfolio mortgage lending by wanting to have a more streamlined approach to QM," Croal said.

Many credit unions exceed the rule's 500-loan limit even though they remain well under $2 billion in assets, he added.

"It's a complicated calculation to make with the additional ALM requirements," Croal said. "They have to balance what is best for their members with interest rate risk and other factors."