But what could become even worse is the fact that as many as 12 more expect to go under in the next few years. According to the report, "[a] total of 44 plans have said they will fail by 2025, when the Central States, Southeast and Southwest Areas Pension Plan, the largest underfunded plan, expects to run out of money."

And to compound the problem, the Pension Benefit Guaranty Corporation expects its own insurance program to run out of funding in fiscal 2025.

Related: Clock ticking on PBGC multiemployer program

In November of 2018, Cheiron found 121 multiemployer pension plans underfunded by $48.9 billion, but that underfunding is now $7.7 billion—15.7 percent—higher. According to the 2019 study, plans have total assets of $41.8 billion and liabilities of $98.3 billion.

If it weren't for the fact that seven plans actually ceased to exist after failing or shutting down, the number of struggling plans would have risen to 124 in 2019. In addition, a few plans did actually do better financially after the Treasury Department approved letting them cut benefits for retirees under the Multiemployer Pension Reform Act.

Three plans account for 62.4 percent of the unfunded liability, totaling $35.3 billion:

• Central States
• The New England Teamsters and Trucking Industry Pension Fund
• The Bakery, Confectionery, Tobacco Workers and Grain Millers International Union pension fund.

They cover 571,801 participants, or 41.8 percent of the 1.4 million participants in all financially troubled multiemployer pension plans. The PBGC covers a total of 1,400 multiemployer pension plans with 10.8 million participants.

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