With everybody studying millennials these days, especially as many engage in jobhopping, it's no surprise that employers are trying to figure out what makes them tick so they don't jump ship and cost thousands to replace.

Pentegra surveyed millennials to see what their attitudes are on benefits and "other issues of importance to millennials when seeking employment," and HR professionals on best practices. The "2018 Millennial Benefit Trends Report" provides a look at what's important to millennials, as well as suggestions from HR personnel on ways to tackle millennial attitudes and priorities on benefits.

At the top of the list, millennials placed "401(k) Retirement Savings"—in fact, 39.8 percent scored it as "extremely important," considerably more than the two runners-up.