Millennials are the biggest and most educated generation in the history of the U.S. Although they constitute a sizeable 30% of the workforce, don't automatically assume they are ideal prospects for your bank or credit union.

Almosta quarter (23%) say they carry less than $5 in cash seven days a week, according to a survey conducted by the Independent Community Bankers of America. About 40% report that they are overwhelmed by debt obligations, primarily from credit cards and student loans. A majority report they are living paycheck to paycheck, according to the Wells Fargo Millennial Survey.

Undeterred by such cautionary data, restaurant chains, luxury brands, clothing retailers, and travel firms are scrambling for a piece of a generation generally viewed as having more buying power than any in recent memory.

Big banks, by dangling the latest mobile technology as a carrot, are winning over more than two thirds of millennials according to a 2014 FICO Millennial Study. Community banks may not be faring nearly as well – but that may be a blessing.

As with most segments based on age, only certain prospects are attractive. Before cranking up a millennial effort, CEOs and marketers must carefully consider whether an acquisition program is worthwhile.

Consumer behaviors and attitudes don't abruptly develop and end with specific birthdays. Each person marches to their own drumbeat, taking their own time to form opinions and establish behaviors. Parents would like children to start making sensible decisions when they turn 21 – but that's not the way it works. Millennials tend to be as diverse, affluent, cynical, optimistic, ethical, thrifty and altruistic as the parents who raised them. Their only commonalities are shared experiences which don't result in uniform attitudes and behaviors.

We can speculate about the impact of 9/11, the wars in Afghanistan and Iraq, and the Great Recession of 2008 but it's probably not powerful enough to justify a separate retail banking campaign.

Banks have valid reasons for acquiring young customers – to counter natural attrition, expand market share, cultivate advocates or simply increase profits – but those reasons must be tempered with realistic expectations. Not all millennials are ideal targets for community banks.

Nearly two-thirds make less than $50,000 a year in household income, 23% spend more than they make, and 31% have unpaid medical debts, according to the 2014 FINRA Financial Education Capability Study.

Millennials have a higher delinquency rate on their bills than any generation. More than a quarter of millennials surveyed had missed a bill or been contacted by a creditor due to late payments, according to a recent study by the American Institute of CPAs.

They switch banks at twice the rate of older customers, are more interested in technology than service, see little difference between institutions. A third of millennials believe they'll live bank-free in the future, according to a recent Accenture study.

Since they are just starting their careers, you might expect millennials to be good credit prospects. In fact, 63% (of those ages 18 to 29) don't have a credit card, according to a survey commissioned by Bankrate and compiled by Princeton Survey Research Associates International.

But that doesn't mean they are good credit risks. According to Experian, the average VantageScore for millennials is 628, which lenders largely consider subprime. Baby boomers and Generation Xers have an average VantageScore of 700 and 653, respectively.

We should avoid viewing millennials as a monolithic group. Even a majority of millennials don't think the term describes them. Consider parsing them into subgroups such as affluent, homebuyers, entrepreneurs and savers. But the smarter move may be to remove the age bracket blinders entirely and just target the best prospects for specific products.

Nielsen, Raddon and other vendors can pinpoint consumer segments with the resources and propensity to purchase specific financial products. These vendors divide the population into dozens of lifestyles and each lifestyle member exhibits similar attitudes and needs towards money. By appending this lifestyle information to your customer database, you can quickly determine which lifestyles are attracted to your institution and to particular products. Purchase email or address lists of matching prospects in your area and reach them through the most appropriate channels.

Leave millennials to the big banks; focus on profitable prospects.

Kevin Tynan is senior vice president of marketing at Liberty Bank in Chicago.

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