estimate of the effect of the Tax Act, increased net income - Omnicom Group Inc. in 2018 by $18.2 million. Diluted net income per share - Omnicom Group Inc. increased 3.9% to $6.06 in 2019, compared to $5.83 in 2018, due to the factors described above, as well as the impact of the reduction in our weighted average common shares outstanding resulting from repurchases of our common stock, net of shares issued for restricted stock awards, stock option exercises and the employee stock purchase plan. The net gain on disposition of subsidiaries and repositioning charges net of the additional income tax expense from the finalization of the provisional estimate of the effect of the Tax Act, increased diluted net income per share - Omnicom Group Inc. in 2018 by $0.08, and Non-GAAP diluted net income per share - Omnicom Group Inc. increased 5.4% in 2019 compared to 2018 adjusted for these items. Non-GAAP operating profit, adjusted EBITA, Non-GAAP net income – Omnicom Group Inc., and Non-GAAP diluted net income per share – Omnicom Group Inc. are Non-GAAP financial measures which adjusts the 2018 financial measures for the impact of the net gain on disposition of subsidiaries of $178.4 million and repositioning charges of $149.4 million, a net increase of $3.9 million in income tax expense, and an allocation of $6.9 million to noncontrolling interests for these items. Accordingly, when comparing operating profit, EBITA, net income - Omnicom Group Inc. and diluted net income per share - Omnicom Group Inc. for 2019 to 2018, we also present the 2018 reported amounts and EBITA on page 14 adjusted for the effects of these transactions. We believe these Non-GAAP measures aid investors by providing additional insight into our operational performance and help clarify trends affecting our business. For comparability of reporting, management considers Non-GAAP measures in conjunction with GAAP financial results in evaluating business performance. These Non-GAAP financial measures presented should not be considered a substitute for, or superior to, the measures of financial performance prepared in accordance with GAAP. Reconciliation of Non-GAAP Financial Measures Year Ended December 31, 2019 2018 Non-GAAP operating profit and adjusted EBITA: Net Income - Omnicom Group Inc. $ 1,339.1  $ 1,326.4  Net Income Attributed To Noncontrolling Interests 96.8  114.1  Net Income 1,435.9  1,440.5  Income From Equity Method Investments 2.0  8.9  Income Tax Expense 504.4  492.7  Income Before Income Taxes and Income From Equity Method Investments 1,938.3  1,924.3  Interest Expense 244.3  266.4  Interest Income 60.3  57.2  Operating profit 2,122.3  2,133.5  Net gain on disposition of subsidiaries —  (178.4) Repositioning charges —  149.4  Non-GAAP operating profit 2,122.3  2,104.5  Add back: Amortization of intangible assets 83.8  102.5  Adjusted EBITA $ 2,206.1  $ 2,207.0  Non-GAAP net income - Omnicom Group Inc. and Non-GAAP diluted net income per share Omnicom Group Inc.: Net income - Omnicom Group Inc. $ 1,339.1  $ 1,326.4  Net pre-tax gain on disposition of subsidiaries and repositioning actions —  (29.0) Net income tax benefit of gain on disposition of subsidiaries and repositioning actions —  (25.0) Allocation to noncontrolling interests —  6.9  Net increase in tax expense related to the Tax Act —  28.9  Non-GAAP net income - Omnicom Group Inc. $ 1,339.1  $ 1,308.2  Diluted Net Income Per Share - Omnicom Group Inc. $ 6.06  $ 5.83  Net gain on disposition of subsidiaries, repositioning actions and impact of Tax Act —  (0.08) Non-GAAP diluted net income per share - Omnicom Group Inc. $ 6.06  $ 5.75  Weighted average shares 220.9  227.6  The following table reconciles our financial results presented above to the Non-GAAP Financial Measures (in millions, except per share amounts): 24