The Financial Accounting Standards Board (FASB) has issued new accounting rules related to defined benefit (DB) pension plans. One result is that the net funded position of a DB plan will be reported on the balance sheet of the plan sponsor. With the anticipation that the year-to-year funding variability will increase income statement and cash flow volatility, plan sponsors are seeking solutions to mitigate the problem. One potential solution is Liability Driven Investing (LDI). In a nutshell, LDI is new way to look at a DB plan's asset allocation within the framework of reducing plan sponsor financial statement and funding volatility.
The attached research paper written by Michael J. Senoski of Pyramis Global Advisors provides additional information. It's a good introduction, but don't forget he has something to sell.