Baby boomers are hitting "peak 65." Two-thirds don't have nearly enough saved for retirement.

The nation is rapidly approaching "peak 65" as younger baby boomers turn 65 this year, initiating the biggest wave of retirements in U.S. history. Yet most of those Americans are financially unprepared to stop working, and many risk living in poverty, according to a new analysis. 

The retirements of the youngest boomers — those born between 1959 and 1965 — are likely to reshape the U.S. economy, and not in entirely positive ways, according to the study from the ALI Retirement Income Institute, a non-profit focused on retirement education. 

The new research underscores the impact that income and wealth inequality has had on a generation that, at least on aggregate, is the nation's wealthiest. Boomers who are White, male or have college degrees are the most likely to be financially prepared for retirement, but many people of color, women and those with only high school educations are lagging, the study found.