The Pension Benefit Guaranty Corp., which insures retirement plans for millions of workers and retirees, says its multiemployer program lost $404 million in fiscal 2006, up from $99 million in 2005.

In its annual management report, released Nov. 15, PBGC pegs multiemployer plans' 2006 underfunding at $150 billion, down from $200 billion in 2005. About half of the 1,540 PBGC-insured multiemployer plans and 30% of the 9.9 million individuals such plans cover are in construction.

A pension law enacted Aug. 17 aims to make multiemployer plans stronger, but those improvements will take time. Heidi Blumenthal, an Associated General Contractors' congressional relations director, says multiemployer plan trustees are "all looking for ways to make their plans healthier."