Notes to Consolidated Financial Statements
(Amounts in Millions, Except Per Share Amounts)
assess the likelihood of additional tax assessments in those jurisdictions and adjust our reserves as additional information or events require.
Redeemable Noncontrolling Interests
Many of our acquisitions include provisions under which the noncontrolling equity owners can require us to purchase additional interests in a subsidiary at their discretion. Payments for these redeemable noncontrolling interests may be contingent on projected operating performance and satisfying other conditions specified in the related agreements. These payments are also subject to revision in accordance with the terms of the agreements. We record these redeemable noncontrolling interests in “mezzanine equity” in our Consolidated Balance Sheets. Each reporting period, redeemable noncontrolling interests are reported at their estimated redemption value, but not less than their initial fair value. Any adjustment to the redemption value above initial value prior to exercise will also impact retained earnings or additional paid-in capital, but will not impact net income. Adjustments as a result of currency translation will affect the redeemable noncontrolling interest balance, but do not impact retained earnings or additional paid-in capital.
Earnings Per Share (“EPS”)
Basic EPS available to IPG common stockholders equals net income available to IPG common stockholders divided by the weighted-average number of common shares outstanding for the applicable period. Diluted EPS equals net income available to IPG common stockholders adjusted to exclude, if dilutive, preferred stock dividends, interest expense related to potentially dilutive securities calculated using the effective interest rate method and the benefit from the preferred stock repurchased, divided by the weighted-average number of common shares outstanding, plus any additional common shares that would have been outstanding if potentially dilutive shares had been issued.
Diluted EPS reflect the potential dilution that would occur if certain potentially dilutive securities or debt obligations were exercised or converted into common stock. The potential issuance of common stock is assumed to occur at the beginning of the year (or at the time of issuance of the potentially dilutive instrument, if later) and the incremental shares are included using the treasury stock or “if-converted” method. The proceeds utilized in applying the treasury stock method consist of the amount, if any, to be paid upon exercise and, as it relates to stock-based compensation, the amount of compensation cost attributed to future service not yet recognized and any tax benefits credited to additional paid-in-capital related to the exercise. These proceeds are then assumed to be used to purchase common stock at the average market price of our stock during the period. The incremental shares (difference between the shares assumed to be issued and the shares assumed to be purchased), to the extent they would have been dilutive, are included in the denominator of the diluted EPS calculation.
We may be required to calculate basic EPS using the two-class method as a result of our redeemable noncontrolling interests. To the extent that the redemption value increases and exceeds the then-current fair value of a redeemable noncontrolling interest, net income available to IPG common stockholders (used to calculate EPS) could be negatively impacted by that increase, subject to certain limitations. The partial or full recovery of any reductions to net income available to IPG common stockholders (used to calculate EPS) is limited to any cumulative prior-period reductions. For the years ended December 31, 2015, 2014 and 2013, there was no impact to EPS for adjustments related to our redeemable noncontrolling interests.
Pension and Postretirement Benefits
We have pension and postretirement benefit plans covering certain domestic and international employees. We use various actuarial methods and assumptions in determining our net pension and postretirement benefit costs and obligations, including the discount rate used to determine the present value of future benefits, expected long-term rate of return on plan assets and healthcare cost trend rates. The overfunded or underfunded status of our pension and postretirement benefit plans is recorded on our Consolidated Balance Sheet.
Compensation costs related to share-based transactions, including employee stock options, are recognized in the Consolidated Financial Statements based on fair value. Stock-based compensation expense is generally recognized ratably over the requisite service period based on the estimated grant-date fair value, net of estimated forfeitures.
We account for repurchased common stock under the cost method and include such treasury stock as a component of our Consolidated Statements of Stockholders' Equity. Upon retirement, we reduce common stock for the par value of the shares being retired and the excess of the cost of the shares over par value as a reduction to additional paid-in capital ("APIC"), to the extent