Here's what the U.S. retirement industry looks like, from target-date funds to defined benefit plans, to DC plans, to IRAs. (Photo: iStock)

The U.S. retirement market was valued at $27.2 trillion at the end of the third quarter this year, according to the Investment Company Institute.

That marked a full $1 trillion gain from the end of the second quarter in 2017, and nearly $10 trillion more than at the end of 2010.

Government and private sector-sponsored defined benefit plans, defined contribution plans, IRAs, and annuity reserves are counted by the ICI. Social Security benefits are not.

IRAs held $8.6 trillion at the end of the third quarter, representing the largest swath of the retirement market, an increase of 2.7 percent from the end of the second quarter, and up from $5 trillion in 2010.

About half of IRA assets are held in mutual funds, with $2.3 trillion being managed in equity funds.

Defined contribution plans held 7.7 trillion, up 2.5 percent from the second quarter, for an increase of nearly $3 trillion since 2010. 401(k) plans held $5.3 trillion.

Mutual funds accounted for $3.5 trillion, or 65 percent of the assets in 401(k) plans, with $2.1 trillion held in equity funds.

Strong equity markets have continued to stretch total retirement savings assets into new record territory. The Dow Jones Stock Exchange is up more than 25 percent in 2017.

Target-date funds reached $1.1 trillion in assets by the end of the third quarter, up 5 percent from the previous quarter.

About 67 percent of TDF assets are held in defined contribution plans, and another 20 percent held in IRAs.

The $708 billion in TDFs held in DC plans represents perhaps the most stratospheric assent for any investment vehicle in retirement plans. In 2010, TDFs in DC plans held just $240 billion.

Private sector defined benefit plans held $3.1 trillion at the end of third quarter.

In 2000, private sector defined benefits accounted for 17 percent of what was then an $11.6 trillion retirement market.

Today, the plans account for about 11 percent of total retirement assets.

As a percentage of total assets, defined contribution plans have increased marginally over the past two decades.

In 2000, DC plans accounted for 26 percent of what was then an $11.6 trillion retirement market.

Today DC plans account for 28 percent of the $27.2 trillion retirement market.