Changing jobs throughout a career is not uncommon, but it has contributed to millions of Americans leaving behind retirement savings in their 401(k) plans, MarketWatch reported. According to a recent study conducted by Capitalize, a company that specializes in helping individuals roll over employer-sponsored retirement assets, about 2.8 million 401(k) plans are left behind every year. In total, there is an estimated $1.35 trillion balance in “forgotten” plans held by more than 24 million participants, the study found. The average balance in a forgotten 401(k) is $55,400. Forgotten 401(k) plans could cost individuals nearly $700,000 in lost retirement savings over their lifetimes because of the risks of higher fees and lower returns. The researchers looked at data from the Department of Labor, Census Bureau and 401(k) record-keepers, and used “well-allocated” IRA data to analyze the potential losses.