The funded ratio of Towers Perrin's hypothetical benchmark plan declined 4% in June to 66.9%, according to a Towers Perrin news release.
The plan's funded ratio is up 1.4% for the six months ended June 30, but down 23% in the latest 12-month period.
The hypothetical benchmark plan, made up of 60% equities and 40% fixed income, had an investment return of 0.3% in June and 3.9% year-to-date June 30. Liabilities rose 4.6% in June and were up 1.8% year-to-date.
The monthly update was expanded in June to include a survey of financial results of 300 large U.S. companies' pension plans.
Towers Perrin estimates the companies' plans were underfunded by a combined $344 billion as of June 30, the release said. The same plans had a $47 billion surplus at the end of fiscal year 2007 and a deficit of $339 billion at the end of fiscal year 2008.