According to AB Global, it appears that many sponsors are "confused or misinformed" — not only about QDIAs, but about knowing that they are, in fact, fiduciaries (30 percent fail to realize this).

Some of the lack of understanding can be attributed to "the philosophical divide between the 'paternal' and 'hands-off' plan perspectives, with the former choosing more proactive features such as auto-escalation and goals like improving participation rates and improving salary deferral amounts."

The latter tend to believe that plan participants want to make their own decisions, and are "also less likely to have an investment policy statement providing guidelines for fiduciaries on making investment decisions (41 percent vs. 53 percent)," the company said.

Among plan sponsors whose plans do not have a QDIA as a default investment, only 48 percent consider themselves plan fiduciaries. In addition, they put fiduciary issues lower on the totem pole (just 33 percent recognize that they are "very important," compared with 56 percent of those with a designated QDIA as default).

And just 15 percent of those whose default is not a QDIA plan to change to a QDIA within the next two years. 

Among those whose plans do have a designated QDIA as a default, 70 percent recognize that they are indeed fiduciaries.

"While it's surprising that roughly half our survey population doesn't take advantage of QDIA safe harbor protections, the large size and balanced demographic representation of our study make this finding hard to dismiss. Many sponsors appear to be confused or misinformed even though respondents were screened to be sure they are fiduciaries," said Richard Davies, senior managing director of defined contribution and co-head North America of AB Institutional Investments.

Also read: GAO to look at TDFs, other QDIAs