Kay also is the president/CEO of LOMTO, which carries the fifth highest average loan balance per member of $194,686 as of June 2014 on the CU Times Top 20 list of the leaders in average loan balance.

“Our members here are not really wealthy people for the most part. They are cab drivers,” Kay said. “These members are hardworking blue-collar guys that elevated themselves in the taxi industry to own a medallion instead of driving for somebody else, which is why they have these large loan balances.”

Melrose Credit Union managed the second highest average loan balance at $355,674 as of June, according to the CU Times list. Progressive ranked third with an average loan balance of $266,611 and Montauk ranked sixth with an average loan balance of $190,930.

Read more: Churches aren't cheap …

The Institute for the Study of American Evangelicals in Wheaton, Ill., estimated 100 million Americans are evangelicals who worship and socialize at thousands of churches across the nation. Some of these worship centers in 30 states are financed by the $1 billion Evangelical Christian Credit Union in Brea, Calif.

“We look a lot like a commercial bank from our customer base,” Mike Boblit, vice president for Evangelical Christian, explained. “The majority of our members are not exclusively churches, but the majority of them are churches and the majority of our loans are real estate- secured loans that are secured by church facilities.”

That may also explain why Evangelical Christian has the fourth highest average loan balance of $257,878 on the Top 20 list.

“We really began in earnest [to lend to churches] 20 years ago,” Boblit said. “There was a real recognition that many churches didn't have a lot of options for borrowing money because commercial banks didn't really understand their source of income and their expenses. When we started church loans, it was primarily related to our ability to understand income sources, understand how churches spent money and how to assess whether the church would repay the loan.”

Like the housing market, churches were not immune to the impact of the Great Recession. From 2009 to 2011, Evangelical Christian posted a total net income loss of more than $39 million, according to NCUA financial performance reports. The California cooperative was also embroiled in foreclosure cases that drew national media attention about church bankruptcies.

Though Evangelical Christian's total loans and loan income continued to decline slightly in 2012 and 2013, the credit union managed to turn a total net gain of $7.4 million in those years according to NCUA financial performance reports.

While the credit union posted a net income gain of $2.3 million at the end of the first quarter this year and only a small net income loss of $657,389 at the end of June 2014, it recorded a net income loss of $14.7 million by third quarter's end, according to NCUA financial performance reports.

To diversify its portfolio, Evangelical Christian plans to expand its retail consumer products and services through web and mobile banking, according to Boblit. Earlier this year, the credit union hired Robert McDougall, a former executive with JP Morgan Chase Bank, to oversee this new initiative.

Read more: MBLs to immigrants build balances …

The $260 million Ukrainian Self-Reliance Federal Credit Union was established in the early 1950s to serve Ukrainian WWII immigrants.

“When they immigrated to this country, the first thing they wanted was a home, a permanent place to be part of the community,” Mary Kolodij, president/CEO of the Philadelphia-based cooperative and a first generation American of Ukrainian immigrant parents, said. “But they could not get loans not because they were not creditworthy or that they weren't smart enough, it was just a language difficulty.”

Because many of Ukrainian Self-Reliance's employees can fluently speak Ukrainian and Russian, the cooperative has built a loyal membership base, according to Kolodij. The majority of them use the credit union as their primary financial institution, she added. Ukrainian Self-Reliance also has recently moved into the member business loan arena for those who are investing in rental properties.

Of its 1,290 retail loans, more than 960 are first mortgage loans worth $129 million, according to Ukrainian Self-Reliance's NCUA 5300 report. What's more, those loyal members have helped the credit union achieve a No. 9 ranking on the CU Times Top 20 list with an average loan balance of $105,408.

Other credit unions that primarily serve eastern European immigrants made the Top 20 list as well. The $98 million California Lithuanian Credit Union in in Santa Monica, Calif., was No. 1 with an average loan balance of $375,950, and the $1 billion Self Reliance New York, which serves Ukrainian immigrants, was ranked eighth with an average loan balance of $126,045.

Self-Reliance manages a first mortgage loan portfolio of $647 million and California Lithuanian holds a first mortgage portfolio of $67 million, according to their respective 5300 reports.

Throughout the 1990s, a new generation of eastern European immigrants flowed into the U.S. after the fall of the Berlin Wall in 1980, Kolodij said.

“As these immigrants have assimilated into their communities and have become more financially sophisticated, we are increasing our types of products and services so that they will continue to use us as their primary financial institution,” she said. “In about a month, we will be introducing mobile banking with remote capture and new Visa cards with rewards programs.”