Total retirement assets, including money in pension plans in thepublic and private sectors and holdings in IRAs, hit $21.5 trillionin 2014, according to research firm Spectrem Group.

That total is up from $19.6 trillion at the end of 2013, a 9.6percent increase, according to Chicago-based Spectrum, which trackswealthy Americans’ investing habits for large moneymanagers.

Just how much money is that? U.S. gross domestic product isabout $17 trillion, according to the World Bank. China’s is about$9 trillion.

Spectrem's figures closely mirror those of Towers Watson, whichlast month estimated that assets in U.S.institutional retirement funds set a newrecord in 2014 — $22.1 trillion — after gaining 9 percentyear-over-year.

According to Spectrem, about $8.5 trillion of retirement savingsis in private-sector employer-sponsored plans. Corporatedefined-contribution plans alone hold nearly $5.3 trillion, twiceas much as corporate defined-benefit plans.

DC plans have grown at an average rate of 10.2 percent over thepast five years. In 2009, assets in corporate DC plans — which thestudy distinguishes from union-sponsored DC plans — were about $3.2trillion.

Most of that growth is accounted for by 401(k) plans, which held more than $4 trillion by theend of 2014, nearly double the value at the end of 2009.

Assets in 401(k) plans have grown by about 12 percent annuallyover the past five years. Some of that is attributable to thestock-market recovery since the financial crisis.

But steady new plan adoption has also propelled the overallasset value of 401(k) plans. New-plan formation has been 3 percentper year since 2009. Most of the new plans have been established atfirms with fewer than 500 employees, according toSpectrem.

That means there are now 642,400 401(k) plans in the country,and about 52.7 million participants enrolled in them.

IRAs held $7.7 trillion at the end of 2014, mostly in mutualfunds and self-directed brokerage accounts, up from $4.5 trillionin 2009.

IRA assets have grown 11.4 percent annually over the past fiveyears. Spectrem is assuming IRAs will be the fastest-growing amongretirement savings platforms, as baby boomers retire and roll oversavings from DC plans.

Also read: Median retirement account balance drops to$2,500