Verisign provides quarterly and annual financial statements that are prepared in accordance with generally accepted accounting principles (GAAP). Along with this information, we typically disclose and discuss certain non-GAAP financial information in our quarterly earnings release, on investor conference calls and during investor conferences and related events. This non-GAAP financial information does not include the following types of financial measures that are included in GAAP: discontinued operations, stock-based compensation, amortization of other intangible assets, impairments of goodwill and other intangible assets, restructuring charges, contingent interest payments to holders of the subordinated convertible debentures, unrealized gain/loss on contingent interest derivative on subordinated convertible debentures, and non-cash interest expense. Non-GAAP financial information is also adjusted for a 28 percent tax rate starting from the third quarter of 2012 and 30 percent for all other periods presented herein, both of which differ from the GAAP tax rate.
Management believes that this non-GAAP financial data supplements the GAAP financial data by providing investors with additional information that allows them to have a clearer picture of Verisign's operations. The presentation of this additional information is not meant to be considered in isolation nor as a substitute for results prepared in accordance with GAAP. We believe that the non-GAAP information enhances investors' overall understanding of our financial performance and the comparability of Verisign's operating results from period to period. Above, we have provided a reconciliation of the non-GAAP financial information that we provide each quarter with the comparable financial information reported in accordance with GAAP for the given period.
SUPPLEMENTAL FINANCIAL INFORMATION The following table presents the classification of stock-based compensation: Three Months Ended March 31, --------------------------- 2013 2012 ------------- -------------Cost of revenues $ 1,540 $ 1,537Sales and marketing 1,487 1,516Research and development 1,895 1,242General and administrative 2,672 3,835 ------------- -------------Total stock-based compensation expense $ 7,594 $ 8,130 ============= ============= VERISIGN, INC. SUPPLEMENTARY FINANCIAL INFORMATION (Unaudited)
Following the offering of the 4.625% Senior Notes due 2023 (the "Notes"), Verisign is disclosing its Adjusted EBITDA for the periods shown below. Adjusted EBITDA is a non-GAAP financial measure and is calculated in accordance with the terms of the indenture governing the Notes. Adjusted EBITDA refers to net income before interest, taxes, depreciation and amortization, stock-based compensation, unrealized loss (gain) on contingent interest derivative on the subordinated convertible debentures and unrealized loss (gain) on hedging agreements.