Why is everyone concerned about millennials? Consider a few facts about this generation:

• Millennials are projected to surpass baby boomers as the nation's largest living adult generation, according to population projections from the U.S. Census Bureau.
• They're already currently the largest generation in the U.S. labor force.
• They were the first generation to come of age in the new millennium — born between 1981 and 1996, according to the Pew Research Center.
• They're better educated, more diverse, but earn less in a world of increasing inequality.
• They have also been slower to marry and form their own households.

Studies have also shown millennials can be risk averse and reluctant to invest in the stock market. And that they're the generation most widely affected by college debt, with 75% carrying some form of loan debt.

So, how is this affecting their finances?

BenefitsPRO's sister site, ThinkAdvisor, sought the advice of financial planners and advisors to determine what are some of the biggest financial mistakes millennials make. Visit the slideshow gallery above to see what 10 financial professionals see as millennials' biggest financial mistakes.