Millennials have an itchy trigger finger when it comes to investments, reacting to market volatility with unwise decisions—but they're less likely to seek out professional financial advice.

That's according to the MassMutual Retirement Savers Study from Massachusetts Mutual Life Insurance Co., which finds that millennials are all too ready to reallocate retirement savings when the market gyrates, but the decisions they make when things are in flux can be the wrong ones for their long-term plans.

While 60 percent of older adult Americans, according to the study, say they're leaving their retirement savings strategy as is—including 63 percent of women and 56 percent of men—just 23 percent of millennials are sticking to their guns, compared with 59 percent of those aged 34–49, 74 percent of those aged 50–64 and 82 percent of those aged 65 and older.