New data from Kehrer Bielan Research & Consulting showed credit unions have work to do when it comes to attracting more retail investing customers. However, it's worth the effort, given that the study also shows a successful retail investment program can yield something far more valuable than extra fee income: Loyalty.

Only about 10% of people say they would consult a credit union about investing a $25,000 windfall, but people who do end up buying investments at their primary financial institutions are far more likely to have higher deposit and savings balances, have more asset management accounts, and are more likely to say they won't switch financial institutions, according to the study.

In fact, loyalty goes up 42% when a member buys an insurance or investment product through a credit union, David Foster, who is vice president of wealth management at CUNA Mutual Group, pointed out.