The funded status of the 100 largest corporate defined benefit pension plans improved by $32 billion during September as measured by the Milliman 100 Pension Funding Index (PFI). The deficit dropped to $132 billion from $164 billion at the end of August, primarily due to a robust investment gain of more than 2% during September. The projected benefit obligation (PBO), or pension liabilities, decreased to $1.527 trillion from $1.532 trillion at the end of August. The $132 billion pension deficit for the Milliman 100 PFI is a stellar improvement over the $469 billion pension deficit experienced just one year ago.