us U.S. retirement funds lost almost $1 trillion of their value in the year ended Sept. 30, the worst decline in the 30 years Pensions & Investments has tracked the largest 1,000 plans. The fourth quarter of 2008 made it worse: P&I estimates assets of the plans fell an additional $754 billion, or 11.8%. That puts the total loss at $1.7 trillion, or 23.3%, for the 15 months ended Dec. 31.