to January 1, 2009, in the event that an adjustment to the income tax provision relates to a pre-emergence tax position or Northwest Merger-related tax position, we would adjust goodwill followed by other indefinite-lived intangible assets until the net carrying value of these assets is zero. Beginning January 1, 2009, any adjustments to the income tax provision in regard to pre-emergence tax positions will be made through the income tax provision pursuant to SFAS No. 141 (revised 2007), “Business Combinations” (“SFAS 141R”).

For additional information about income taxes, see Notes 1 and 9 of the Notes to the Consolidated Financial Statements.

 

Pension Plans . We sponsor DB Plans for our eligible employees and retirees. We currently estimate that expense for our DB Plans in 2009 will be approximately $420 million. The effect of our DB Plans on our Consolidated Financial Statements is subject to many assumptions. We believe the most critical assumptions are (1) the weighted average discount rate and (2) the expected long-term rate of return on the assets of our DB Plans. For additional information regarding these assumptions, see Note 10 of the Notes to the Consolidated Financial Statements.

We determine our weighted average discount rate on our measurement date primarily by reference to annualized rates earned on high quality fixed income investments and yield-to-maturity analysis specific to our estimated future benefit payments. We used a weighted average discount rate of 6.49% and 6.37% at December 31, 2008 and 2007, respectively. Additionally, our weighted average discount rate for net periodic benefit cost in each of the past three years has varied from the rate selected on our measurement date, ranging from 5.67% to 7.19% between 2006 and 2008, due to remeasurements throughout the year. The impact of a 0.50% change in our weighted average discount rate is shown in the table below.

The expected long-term rate of return on the assets of our DB Plans is based primarily on plan specific investment studies using historical returns on our DB Plans’ assets with forward looking estimates based on existing financial market conditions and forecasts. Modest excess return expectations versus some market indices are incorporated into the return projections based on the actively managed structure of the investment programs and their records of achieving such returns historically. We review our rate of return on plan asset assumptions annually. These assumptions are largely based on the asset category rate-of-return assumptions developed annually with our pension investment advisors, however, our annual investment performance for one particular year does not, by itself, significantly influence our evaluation. The investment strategy for pension plan assets is to utilize a diversified mix of global public and private equity portfolios, public and private fixed income portfolios, and private real estate and natural resource investments to earn a long-term investment return that meets or exceeds a 9% annualized return target. The impact of a 0.50% change in our expected long-term rate of return is shown in the table below.

 

For additional