ACV is a financial performance metric that ANSYS introduced in 2018. The Company believes this measure is an improved metric as compared to the historically provided bookings metric because it adjusts the sales bookings metric to reflect only the annual value of a contract and also adjusts to reflect the sales booking at the date of the contract inception or renewal. There is no GAAP measure comparable to ACV. ACV is composed of the following:

• the annualized value of maintenance and lease contracts with start dates or anniversary dates during the period, plus
• the value of perpetual license contracts with start dates during the period, plus
• the annualized value of fixed-term services contracts with start dates or anniversary dates during the period, plus
• the value of work performed during the period on fixed-deliverable services contracts.

Management's 2019 Financial Outlook

The Company's fourth quarter and fiscal year 2019 revenue and diluted earnings per share guidance is provided below. The revenue and diluted earnings per share guidance is provided on both a GAAP and non-GAAP basis. Non-GAAP financial measures exclude the income statement effects of acquisition adjustments to deferred revenue, stock-based compensation, amortization of acquired intangible assets, acquisition-related transaction costs and adjustments related to the transition tax associated with the Tax Cuts and Jobs Act.

The financial guidance below is adjusted for the impacts of the Company's acquisitions that closed during the fourth quarter. For the impacts of Q4 acquisitions on key guidance metrics, refer to "ANSYS 3Q 2019 Prepared Remarks" that can be accessed by clicking News & Events, then Presentations on our website at https://investors.ansys.com.

Fourth Quarter 2019 Guidance

The Company currently expects the following for the quarter ending December 31, 2019:

Fiscal Year 2019 Guidance

The Company currently expects the following for the fiscal year ending December 31, 2019:

In the fourth quarter and fiscal year 2019 guidance reflected above, the expected impacts of non-GAAP adjustments associated with the acquisition accounting for deferred revenue, including an estimate for the Company's Q4 acquisitions, range from $3.9 million to $4.5 million and $10.1 million to $10.7 million, respectively. The Company has not yet performed a valuation of the acquired deferred revenue for its Q4 acquisitions. Until such valuation is completed, the expected impacts on revenue will remain preliminary estimates that are likely to change.